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Hunter CT, McCarty DR, Koch KE. Independent evolution of transposase and TIRs facilitated by recombination between Mutator transposons from divergent clades in maize. Proc Natl Acad Sci U S A 2023; 120:e2305298120. [PMID: 37490540 PMCID: PMC10401008 DOI: 10.1073/pnas.2305298120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 05/25/2023] [Indexed: 07/27/2023] Open
Abstract
Nearly all eukaryotes carry DNA transposons of the Robertson's Mutator (Mu) superfamily, a widespread source of genome instability and genetic variation. Despite their pervasive impact on host genomes, much remains unknown about the evolution of these transposons. Transposase recognition of terminal inverted repeats (TIRs) is thought to drive and constrain coevolution of MuDR transposase genes and TIRs. To address the extent of this relationship and its impact, we compared separate phylogenies of TIRs and MuDR gene sequences from Mu elements in the maize genome. Five major clades were identified. As expected, most Mu elements were bound by highly similar TIRs from the same clade (homomorphic type). However, a subset of elements contained dissimilar TIRs derived from divergent clades. These "heteromorphs" typically occurred in multiple copies indicating active transposition in the genome. In addition, analysis of internal sequences showed that exchanges between elements having divergent TIRs produced new mudra and mudrb gene combinations. In several instances, TIR homomorphs had been regenerated within a heteromorph clade with retention of distinctive internal MuDR sequence combinations. Results reveal that recombination between divergent clades facilitates independent evolution of transposase (mudra), transposase-binding targets (TIRs), and capacity for insertion (mudrb) of active Mu elements. This mechanism would be enhanced by the preference of Mu insertions for recombination-rich regions near the 5' ends of genes. We suggest that cycles of recombination give rise to alternating homo- and heteromorph forms that enhance the diversity on which selection for Mu fitness can operate.
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Affiliation(s)
- Charles T. Hunter
- Chemistry Research Unit, Center for Medical, Agricultural and Veterinary Entomology, United States Department of Agriculture - Agricultural Research Service, Gainesville, FL32608
| | - Donald R. McCarty
- Horticultural Sciences Department, College of Agricultural and Life Sciences, University of Florida, Gainesville, FL32611
| | - Karen E. Koch
- Horticultural Sciences Department, College of Agricultural and Life Sciences, University of Florida, Gainesville, FL32611
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2
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Langer M, Hilo A, Guan JC, Koch KE, Xiao H, Verboven P, Gündel A, Wagner S, Ortleb S, Radchuk V, Mayer S, Nicolai B, Borisjuk L, Rolletschek H. Causes and consequences of endogenous hypoxia on growth and metabolism of developing maize kernels. Plant Physiol 2023; 192:1268-1288. [PMID: 36691698 PMCID: PMC10231453 DOI: 10.1093/plphys/kiad038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 12/13/2022] [Accepted: 12/19/2022] [Indexed: 06/01/2023]
Abstract
Maize (Zea mays) kernels are the largest cereal grains, and their endosperm is severely oxygen deficient during grain fill. The causes, dynamics, and mechanisms of acclimation to hypoxia are minimally understood. Here, we demonstrate that hypoxia develops in the small, growing endosperm, but not the nucellus, and becomes the standard state, regardless of diverse structural and genetic perturbations in modern maize (B73, popcorn, sweet corn), mutants (sweet4c, glossy6, waxy), and non-domesticated wild relatives (teosintes and Tripsacum species). We also uncovered an interconnected void space at the chalazal pericarp, providing superior oxygen supply to the placental tissues and basal endosperm transfer layer. Modeling indicated a very high diffusion resistance inside the endosperm, which, together with internal oxygen consumption, could generate steep oxygen gradients at the endosperm surface. Manipulation of oxygen supply induced reciprocal shifts in gene expression implicated in controlling mitochondrial functions (23.6 kDa Heat-Shock Protein, Voltage-Dependent Anion Channel 2) and multiple signaling pathways (core hypoxia genes, cyclic nucleotide metabolism, ethylene synthesis). Metabolite profiling revealed oxygen-dependent shifts in mitochondrial pathways, ascorbate metabolism, starch synthesis, and auxin degradation. Long-term elevated oxygen supply enhanced the rate of kernel development. Altogether, evidence here supports a mechanistic framework for the establishment of and acclimation to hypoxia in the maize endosperm.
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Affiliation(s)
- Matthias Langer
- Molecular Genetics Department, Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung, Corrensstrasse, 06466 Seeland-Gatersleben, Germany
| | - Alexander Hilo
- Molecular Genetics Department, Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung, Corrensstrasse, 06466 Seeland-Gatersleben, Germany
| | - Jiahn-Chou Guan
- University of Florida, Horticultural Sciences Department, Fifield Hall, 2550 Hull Rd., PO Box 110690, Gainesville, Florida, 32611, USA
| | - Karen E Koch
- University of Florida, Horticultural Sciences Department, Fifield Hall, 2550 Hull Rd., PO Box 110690, Gainesville, Florida, 32611, USA
| | - Hui Xiao
- Biosystems Department, KU Leuven—University of Leuven, BIOSYST-MeBioS, Willem de Croylaan 42, B-3001 Leuven, Belgium
| | - Pieter Verboven
- Biosystems Department, KU Leuven—University of Leuven, BIOSYST-MeBioS, Willem de Croylaan 42, B-3001 Leuven, Belgium
| | - Andre Gündel
- Molecular Genetics Department, Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung, Corrensstrasse, 06466 Seeland-Gatersleben, Germany
| | - Steffen Wagner
- Molecular Genetics Department, Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung, Corrensstrasse, 06466 Seeland-Gatersleben, Germany
| | - Stefan Ortleb
- Molecular Genetics Department, Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung, Corrensstrasse, 06466 Seeland-Gatersleben, Germany
| | - Volodymyr Radchuk
- Molecular Genetics Department, Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung, Corrensstrasse, 06466 Seeland-Gatersleben, Germany
| | - Simon Mayer
- Molecular Genetics Department, Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung, Corrensstrasse, 06466 Seeland-Gatersleben, Germany
| | - Bart Nicolai
- Biosystems Department, KU Leuven—University of Leuven, BIOSYST-MeBioS, Willem de Croylaan 42, B-3001 Leuven, Belgium
| | - Ljudmilla Borisjuk
- Molecular Genetics Department, Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung, Corrensstrasse, 06466 Seeland-Gatersleben, Germany
| | - Hardy Rolletschek
- Molecular Genetics Department, Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung, Corrensstrasse, 06466 Seeland-Gatersleben, Germany
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3
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Guan JC, Li C, Flint-Garcia S, Suzuki M, Wu S, Saunders JW, Dong L, Bouwmeester HJ, McCarty DR, Koch KE. Maize domestication phenotypes reveal strigolactone networks coordinating grain size evolution with kernel-bearing cupule architecture. Plant Cell 2023; 35:1013-1037. [PMID: 36573016 PMCID: PMC10015167 DOI: 10.1093/plcell/koac370] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 11/15/2022] [Indexed: 06/17/2023]
Abstract
The maize (Zea mays) ear represents one of the most striking domestication phenotypes in any crop species, with the cob conferring an exceptional yield advantage over the ancestral form of teosinte. Remodeling of the grain-bearing surface required profound developmental changes. However, the underlying mechanisms remain unclear and can only be partly attributed to the known domestication gene Teosinte glume architecture 1 (Tga1). Here we show that a more complete conversion involves strigolactones (SLs), and that these are prominent players not only in the Tga1 phenotype but also other domestication features of the ear and kernel. Genetic combinations of a teosinte tga1 allele with three SL-related mutants progressively enhanced ancestral morphologies. The SL mutants, in addition to modulating the tga1 phenotype, also reshaped kernel-bearing pedicels and cupules in a teosinte-like manner. Genetic and molecular evidence are consistent with SL regulation of TGA1, including direct interaction of TGA1 with components of the SL-signaling system shown here to mediate TGA1 availability by sequestration. Roles of the SL network extend to enhancing maize seed size and, importantly, coordinating increased kernel growth with remodeling of protective maternal tissues. Collectively, our data show that SLs have central roles in releasing kernels from restrictive maternal encasement and coordinating other factors that increase kernel size, physical support, and their exposure on the grain-bearing surface.
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Affiliation(s)
- Jiahn-Chou Guan
- Horticultural Sciences Department, University of Florida, Gainesville, Florida 32610, USA
- Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, Florida 32610, USA
- Genetics Institute, University of Florida, Gainesville, Florida 32610, USA
| | - Changsheng Li
- Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam 100 BE, The Netherlands
| | - Sherry Flint-Garcia
- United States Department of Agriculture – Agricultural Research Service, Columbia, Missouri 65211, USA
| | - Masaharu Suzuki
- Horticultural Sciences Department, University of Florida, Gainesville, Florida 32610, USA
- Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, Florida 32610, USA
- Genetics Institute, University of Florida, Gainesville, Florida 32610, USA
| | - Shan Wu
- Horticultural Sciences Department, University of Florida, Gainesville, Florida 32610, USA
| | - Jonathan W Saunders
- Horticultural Sciences Department, University of Florida, Gainesville, Florida 32610, USA
| | - Lemeng Dong
- Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam 100 BE, The Netherlands
| | - Harro J Bouwmeester
- Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam 100 BE, The Netherlands
| | - Donald R McCarty
- Horticultural Sciences Department, University of Florida, Gainesville, Florida 32610, USA
- Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, Florida 32610, USA
- Genetics Institute, University of Florida, Gainesville, Florida 32610, USA
| | - Karen E Koch
- Horticultural Sciences Department, University of Florida, Gainesville, Florida 32610, USA
- Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, Florida 32610, USA
- Genetics Institute, University of Florida, Gainesville, Florida 32610, USA
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4
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Li C, Dong L, Durairaj J, Guan JC, Yoshimura M, Quinodoz P, Horber R, Gaus K, Li J, Setotaw YB, Qi J, De Groote H, Wang Y, Thiombiano B, Floková K, Walmsley A, Charnikhova TV, Chojnacka A, Correia de Lemos S, Ding Y, Skibbe D, Hermann K, Screpanti C, De Mesmaeker A, Schmelz EA, Menkir A, Medema M, Van Dijk ADJ, Wu J, Koch KE, Bouwmeester HJ. Maize resistance to witchweed through changes in strigolactone biosynthesis. Science 2023; 379:94-99. [PMID: 36603079 DOI: 10.1126/science.abq4775] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Maize (Zea mays) is a major staple crop in Africa, where its yield and the livelihood of millions are compromised by the parasitic witchweed Striga. Germination of Striga is induced by strigolactones exuded from maize roots into the rhizosphere. In a maize germplasm collection, we identified two strigolactones, zealactol and zealactonoic acid, which stimulate less Striga germination than the major maize strigolactone, zealactone. We then showed that a single cytochrome P450, ZmCYP706C37, catalyzes a series of oxidative steps in the maize-strigolactone biosynthetic pathway. Reduction in activity of this enzyme and two others involved in the pathway, ZmMAX1b and ZmCLAMT1, can change strigolactone composition and reduce Striga germination and infection. These results offer prospects for breeding Striga-resistant maize.
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Affiliation(s)
- C Li
- Plant Hormone Biology Group, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, Netherlands
| | - L Dong
- Plant Hormone Biology Group, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, Netherlands
| | - J Durairaj
- Bioinformatics Group, Wageningen University & Research, 6708 PB Wageningen, Netherlands
| | - J-C Guan
- Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA
| | - M Yoshimura
- Laboratorium für Organische Chemie, Department of Chemistry and Applied Biosciences, ETH Zürich, 8093 Zürich, Switzerland.,Syngenta Crop Protection AG, Schaffhauserstrasse 101, CH-4332 Stein, Switzerland.,Kyoto University, iCeMS, Yoshida Ushinomiya-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - P Quinodoz
- Syngenta Crop Protection AG, Schaffhauserstrasse 101, CH-4332 Stein, Switzerland
| | - R Horber
- Syngenta Crop Protection AG, Schaffhauserstrasse 101, CH-4332 Stein, Switzerland
| | - K Gaus
- Syngenta Crop Protection AG, Schaffhauserstrasse 101, CH-4332 Stein, Switzerland
| | - J Li
- Department of Economic Plants and Biotechnology, Yunnan Key Laboratory for Wild Plant Resources, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
| | - Y B Setotaw
- Department of Economic Plants and Biotechnology, Yunnan Key Laboratory for Wild Plant Resources, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
| | - J Qi
- Department of Economic Plants and Biotechnology, Yunnan Key Laboratory for Wild Plant Resources, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
| | - H De Groote
- International Maize and Wheat Improvement Center (CIMMYT), PO Box 1041-00621, Nairobi, Kenya
| | - Y Wang
- Plant Hormone Biology Group, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, Netherlands
| | - B Thiombiano
- Plant Hormone Biology Group, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, Netherlands
| | - K Floková
- Plant Hormone Biology Group, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, Netherlands.,Laboratory of Growth Regulators, Institute of Experimental Botany, The Czech Academy of Sciences and Faculty of Science, Palacký University, Šlechtitelů 27, 783 71 Olomouc, Czech Republic
| | - A Walmsley
- Plant Hormone Biology Group, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, Netherlands
| | - T V Charnikhova
- Plant Hormone Biology Group, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, Netherlands
| | - A Chojnacka
- Plant Hormone Biology Group, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, Netherlands
| | - S Correia de Lemos
- Bioinformatics Group, Wageningen University & Research, 6708 PB Wageningen, Netherlands.,Plant genomics and transcriptomics group, Institute of Biosciences, Sao Paulo State University, 13506-900 Rio Claro, Brazil
| | - Y Ding
- Section of Cell and Developmental Biology, University of California at San Diego; La Jolla, CA 92093, USA
| | - D Skibbe
- Seeds Research, Syngenta Crop Protection, LLC, Research Triangle Park, NC 27709, USA
| | - K Hermann
- Syngenta Crop Protection AG, Schaffhauserstrasse 101, CH-4332 Stein, Switzerland
| | - C Screpanti
- Syngenta Crop Protection AG, Schaffhauserstrasse 101, CH-4332 Stein, Switzerland
| | - A De Mesmaeker
- Syngenta Crop Protection AG, Schaffhauserstrasse 101, CH-4332 Stein, Switzerland
| | - E A Schmelz
- Section of Cell and Developmental Biology, University of California at San Diego; La Jolla, CA 92093, USA
| | - A Menkir
- International Institute of Tropical Agriculture, PMB 5320 Oyo Road, Ibadan, Nigeria
| | - M Medema
- Bioinformatics Group, Wageningen University & Research, 6708 PB Wageningen, Netherlands
| | - A D J Van Dijk
- Bioinformatics Group, Wageningen University & Research, 6708 PB Wageningen, Netherlands
| | - J Wu
- Department of Economic Plants and Biotechnology, Yunnan Key Laboratory for Wild Plant Resources, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
| | - K E Koch
- Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA
| | - H J Bouwmeester
- Plant Hormone Biology Group, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, Netherlands
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Gong T, Brecht JK, Koch KE, Hutton SF, Zhao X. A systematic assessment of how rootstock growth characteristics impact grafted tomato plant biomass, resource partitioning, yield, and fruit mineral composition. Front Plant Sci 2022; 13:948656. [PMID: 36589098 PMCID: PMC9798440 DOI: 10.3389/fpls.2022.948656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 08/23/2022] [Indexed: 06/17/2023]
Abstract
The appropriate selection of rootstock-scion combinations to improve yield and fully realize grafting benefits requires an in-depth understanding of rootstock-scion synergy. Toward this end, we grafted two determinate-type scions [grape tomato ('BHN 1022') and beefsteak tomato ('Skyway')] onto four rootstocks with different characteristics to examine plant growth, yield performance, biomass production, and fruit mineral nutrient composition. The study was conducted during two growing seasons (spring and fall plantings in Florida) under organic production in high tunnels with the non-grafted scions as controls. Rootstocks had previously been designated as either "generative" ('Estamino') or "vegetative" ('DR0141TX') by some commercial suppliers or had not been characterized ['RST-04-106-T' and 'SHIELD RZ F1 (61-802)']. Also, 'Estamino', 'DR0141TX', and 'RST-04-106-T' had been described as more vigorous than 'SHIELD RZ F1 (61-802)'. In both planting seasons (with low levels of soilborne disease pressure), the "vegetative" and "generative" rootstocks increased marketable and total fruit yields for both scions except for the beefsteak tomato grafted with the "vegetative" rootstock in fall planting. Positive effects of 'RST-04-106-T' on fruit yield varied with scions and planting seasons, and were most manifested when grafted with the beefsteak tomato scion in fall planting. 'SHIELD RZ F1 (61-802)' led to similar yields as the non-grafted controls except for grafting with the grape tomato scion in fall planting. For vegetative and fruit biomass, both the "vegetative" and "generative" rootstocks had positive impacts except for the beefsteak tomato in fall planting. For fruit mineral composition, the "vegetative" and "generative" rootstocks, both highly vigorous, consistently elevated fruit P, K, Ca, Zn, and Fe contents on a dry weight basis, whereas the other rootstocks did not. Overall, although the more vigorous rootstocks enhanced tomato plant productivity and fruit minerals, the evidence presented here does not support the suggestion that the so-called "vegetative" and "generative" rootstocks have different impacts on tomato scion yield, biomass production, or fruit mineral contents. More studies with different production systems and environmental conditions as well as contrasting scion genotypes are needed to further categorize the impacts of rootstocks with different vigor and other characteristics on plant biomass production and their implications on fruit yield development.
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Affiliation(s)
- Tian Gong
- Horticultural Sciences Department, University of Florida, Gainesville, FL, United States
| | - Jeffrey K. Brecht
- Horticultural Sciences Department, University of Florida, Gainesville, FL, United States
| | - Karen E. Koch
- Horticultural Sciences Department, University of Florida, Gainesville, FL, United States
| | - Samuel F. Hutton
- Gulf Coast Research and Education Center, University of Florida, Wimauma, FL, United States
| | - Xin Zhao
- Horticultural Sciences Department, University of Florida, Gainesville, FL, United States
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6
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Gong T, Brecht JK, Hutton SF, Koch KE, Zhao X. Tomato fruit quality is more strongly affected by scion type and planting season than by rootstock type. Front Plant Sci 2022; 13:948556. [PMID: 36589104 PMCID: PMC9798217 DOI: 10.3389/fpls.2022.948556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 08/23/2022] [Indexed: 06/17/2023]
Abstract
Previous studies of tomato rootstock effects on fruit quality have yielded mixed results, and few attempts have been made to systematically examine the association between rootstock characteristics and tomato fruit quality. In this study, grape tomato ('BHN 1022') and beefsteak tomato ('Skyway') were grafted onto four rootstocks ['Estamino' (vigorous and "generative"), 'DR0141TX' (vigorous and "vegetative"), 'RST-04-106-T' (uncharacterized), and 'SHIELD RZ F1 (61-802)' (mid-vigor, uncharacterized)] and compared to non-grafted scion controls for two growing seasons (Spring and Fall in Florida) in organically managed high tunnels. In both seasons and for both scions, the two vigorous rootstocks, regardless of their designation as "vegetative" ('DR0141TX') or "generative" ('Estamino'), exhibited negative impacts on dry matter content, soluble solids content (SSC), SSC/titratable acidity (TA), lycopene, and ascorbic acid contents. Similar effects on fruit dry matter content and SSC were also observed with the 'RST-04-106-T' rootstock, although little to no change was seen with grafting onto 'SHIELD RZ F1 (61-802)'. Further studies are needed to elucidate the impact of rootstock vigor on tomato volatile profiles and consumer sensory acceptability in order to better determine whether any of the documented effects are of practical importance. On the other hand, the evident effects of scion cultivar and planting season on fruit quality were observed in most of the measurements. The scion by rootstock interaction affected fruit length, firmness, pH, and total phenolic content, while the planting season by rootstock interaction impacted fruit firmness, pH, total antioxidant capacity, and ascorbic acid and lycopene contents. The multivariate separation pattern of planting season, scion, and rootstock treatments as revealed by the canonical discriminant analysis further indicated that the influence of scion cultivar and planting season on tomato fruit quality could be much more pronounced than the rootstock effects. The fruit color (C* and H°), length and width, SSC, pH, total antioxidant capacity, ascorbic acid, and lycopene contents were the main attributes distinguishing different scion-planting season groups.
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Affiliation(s)
- Tian Gong
- Horticultural Sciences Department, University of Florida, Gainesville, FL, United States
| | - Jeffrey K. Brecht
- Horticultural Sciences Department, University of Florida, Gainesville, FL, United States
| | - Samuel F. Hutton
- Gulf Coast Research and Education Center, University of Florida, Wimauma, FL, United States
| | - Karen E. Koch
- Horticultural Sciences Department, University of Florida, Gainesville, FL, United States
| | - Xin Zhao
- Horticultural Sciences Department, University of Florida, Gainesville, FL, United States
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7
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Yang B, Wang J, Yu M, Zhang M, Zhong Y, Wang T, Liu P, Song W, Zhao H, Fastner A, Suter M, Rentsch D, Ludewig U, Jin W, Geiger D, Hedrich R, Braun DM, Koch KE, McCarty DR, Wu WH, Li X, Wang Y, Lai J. The sugar transporter ZmSUGCAR1 of the nitrate transporter 1/peptide transporter family is critical for maize grain filling. Plant Cell 2022; 34:4232-4254. [PMID: 36047828 PMCID: PMC9614462 DOI: 10.1093/plcell/koac256] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 07/31/2022] [Indexed: 05/07/2023]
Abstract
Maternal-to-filial nutrition transfer is central to grain development and yield. nitrate transporter 1/peptide transporter (NRT1-PTR)-type transporters typically transport nitrate, peptides, and ions. Here, we report the identification of a maize (Zea mays) NRT1-PTR-type transporter that transports sucrose and glucose. The activity of this sugar transporter, named Sucrose and Glucose Carrier 1 (SUGCAR1), was systematically verified by tracer-labeled sugar uptake and serial electrophysiological studies including two-electrode voltage-clamp, non-invasive microelectrode ion flux estimation assays in Xenopus laevis oocytes and patch clamping in HEK293T cells. ZmSUGCAR1 is specifically expressed in the basal endosperm transfer layer and loss-of-function mutation of ZmSUGCAR1 caused significantly decreased sucrose and glucose contents and subsequent shrinkage of maize kernels. Notably, the ZmSUGCAR1 orthologs SbSUGCAR1 (from Sorghum bicolor) and TaSUGCAR1 (from Triticum aestivum) displayed similar sugar transport activities in oocytes, supporting the functional conservation of SUGCAR1 in closely related cereal species. Thus, the discovery of ZmSUGCAR1 uncovers a type of sugar transporter essential for grain development and opens potential avenues for genetic improvement of seed-filling and yield in maize and other grain crops.
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Affiliation(s)
- Bo Yang
- State Key Laboratory of Plant Physiology and Biochemistry (SKLPPB) and National Maize Improvement Center, Department of Plant Genetics and Breeding, China Agricultural University, Beijing 100193, China
| | - Jing Wang
- State Key Laboratory of Plant Physiology and Biochemistry (SKLPPB) and National Maize Improvement Center, Department of Plant Genetics and Breeding, China Agricultural University, Beijing 100193, China
| | - Miao Yu
- State Key Laboratory of Plant Physiology and Biochemistry (SKLPPB), College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Meiling Zhang
- State Key Laboratory of Plant Physiology and Biochemistry (SKLPPB) and National Maize Improvement Center, Department of Plant Genetics and Breeding, China Agricultural University, Beijing 100193, China
| | - Yanting Zhong
- The Key Laboratory of Plant–Soil Interactions (MOE), Department of Plant Nutrition, College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China
| | - Tianyi Wang
- National Maize Improvement Center, Department of Plant Genetics and Breeding, China Agricultural University, Beijing 100193, China
| | - Peng Liu
- Plant Molecular and Cellular Biology Program, Horticultural Sciences Department, Genetics Institute, University of Florida, Gainesville, Florida, USA
| | - Weibin Song
- State Key Laboratory of Plant Physiology and Biochemistry (SKLPPB) and National Maize Improvement Center, Department of Plant Genetics and Breeding, China Agricultural University, Beijing 100193, China
| | - Haiming Zhao
- State Key Laboratory of Plant Physiology and Biochemistry (SKLPPB) and National Maize Improvement Center, Department of Plant Genetics and Breeding, China Agricultural University, Beijing 100193, China
| | - Astrid Fastner
- Institute of Plant Sciences, University of Bern, Bern 3013, Switzerland
| | - Marianne Suter
- Institute of Plant Sciences, University of Bern, Bern 3013, Switzerland
| | - Doris Rentsch
- Institute of Plant Sciences, University of Bern, Bern 3013, Switzerland
| | - Uwe Ludewig
- Institute of Crop Science, Nutritional Crop Physiology (340h), University of Hohenheim, Stuttgart 70593, Germany
| | - Weiwei Jin
- National Maize Improvement Center, Department of Plant Genetics and Breeding, China Agricultural University, Beijing 100193, China
- Center for Crop Functional Genomics and Molecular Breeding, China Agricultural University, Beijing 100193, China
| | - Dietmar Geiger
- Department of Molecular Plant Physiology and Biophysics, Julius-von-Sachs-Institute for Biosciences, University of Würzburg, Würzburg 97082, Germany
| | - Rainer Hedrich
- Department of Molecular Plant Physiology and Biophysics, Julius-von-Sachs-Institute for Biosciences, University of Würzburg, Würzburg 97082, Germany
| | - David M Braun
- Division of Biological Sciences, Interdisciplinary Plant Group, and Missouri Maize Center, University of Missouri, 116 Tucker Hall, Columbia, Missouri 65211, USA
| | - Karen E Koch
- Plant Molecular and Cellular Biology Program, Horticultural Sciences Department, Genetics Institute, University of Florida, Gainesville, Florida, USA
| | - Donald R McCarty
- Plant Molecular and Cellular Biology Program, Horticultural Sciences Department, Genetics Institute, University of Florida, Gainesville, Florida, USA
| | - Wei-Hua Wu
- State Key Laboratory of Plant Physiology and Biochemistry (SKLPPB), College of Biological Sciences, China Agricultural University, Beijing 100193, China
- Center for Crop Functional Genomics and Molecular Breeding, China Agricultural University, Beijing 100193, China
| | - Xuexian Li
- The Key Laboratory of Plant–Soil Interactions (MOE), Department of Plant Nutrition, College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China
- Center for Crop Functional Genomics and Molecular Breeding, China Agricultural University, Beijing 100193, China
| | - Yi Wang
- State Key Laboratory of Plant Physiology and Biochemistry (SKLPPB), College of Biological Sciences, China Agricultural University, Beijing 100193, China
- Center for Crop Functional Genomics and Molecular Breeding, China Agricultural University, Beijing 100193, China
| | - Jinsheng Lai
- State Key Laboratory of Plant Physiology and Biochemistry (SKLPPB) and National Maize Improvement Center, Department of Plant Genetics and Breeding, China Agricultural University, Beijing 100193, China
- Center for Crop Functional Genomics and Molecular Breeding, China Agricultural University, Beijing 100193, China
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8
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Finegan C, Boehlein SK, Leach KA, Madrid G, Hannah LC, Koch KE, Tracy WF, Resende MFR. Genetic Perturbation of the Starch Biosynthesis in Maize Endosperm Reveals Sugar-Responsive Gene Networks. Front Plant Sci 2022; 12:800326. [PMID: 35211133 PMCID: PMC8861272 DOI: 10.3389/fpls.2021.800326] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 12/27/2021] [Indexed: 05/28/2023]
Abstract
In maize, starch mutants have facilitated characterization of key genes involved in endosperm starch biosynthesis such as large subunit of AGPase Shrunken2 (Sh2) and isoamylase type DBE Sugary1 (Su1). While many starch biosynthesis enzymes have been characterized, the mechanisms of certain genes (including Sugary enhancer1) are yet undefined, and very little is understood about the regulation of starch biosynthesis. As a model, we utilize commercially important sweet corn mutations, sh2 and su1, to genetically perturb starch production in the endosperm. To characterize the transcriptomic response to starch mutations and identify potential regulators of this pathway, differential expression and coexpression network analysis was performed on near-isogenic lines (NILs) (wildtype, sh2, and su1) in six genetic backgrounds. Lines were grown in field conditions and kernels were sampled in consecutive developmental stages (blister stage at 14 days after pollination (DAP), milk stage at 21 DAP, and dent stage at 28 DAP). Kernels were dissected to separate embryo and pericarp from the endosperm tissue and 3' RNA-seq libraries were prepared. Mutation of the Su1 gene led to minimal changes in the endosperm transcriptome. Responses to loss of sh2 function include increased expression of sugar (SWEET) transporters and of genes for ABA signaling. Key regulators of starch biosynthesis and grain filling were identified. Notably, this includes Class II trehalose 6-phosphate synthases, Hexokinase1, and Apetala2 transcription factor-like (AP2/ERF) transcription factors. Additionally, our results provide insight into the mechanism of Sugary enhancer1, suggesting a potential role in regulating GA signaling via GRAS transcription factor Scarecrow-like1.
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Affiliation(s)
- Christina Finegan
- Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, FL, United States
- Horticultural Sciences Department, University of Florida, Gainesville, FL, United States
| | - Susan K. Boehlein
- Horticultural Sciences Department, University of Florida, Gainesville, FL, United States
| | - Kristen A. Leach
- Horticultural Sciences Department, University of Florida, Gainesville, FL, United States
| | - Gabriela Madrid
- Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, FL, United States
- Horticultural Sciences Department, University of Florida, Gainesville, FL, United States
| | - L. Curtis Hannah
- Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, FL, United States
- Horticultural Sciences Department, University of Florida, Gainesville, FL, United States
| | - Karen E. Koch
- Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, FL, United States
- Horticultural Sciences Department, University of Florida, Gainesville, FL, United States
| | - William F. Tracy
- Department of Agronomy, University of Wisconsin- Madison, Madison, WI, United States
| | - Marcio F. R. Resende
- Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, FL, United States
- Horticultural Sciences Department, University of Florida, Gainesville, FL, United States
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9
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Sanclemente MA, Ma F, Liu P, Della Porta A, Singh J, Wu S, Colquhoun T, Johnson T, Guan JC, Koch KE. Sugar modulation of anaerobic-response networks in maize root tips. Plant Physiol 2021; 185:295-317. [PMID: 33721892 PMCID: PMC8133576 DOI: 10.1093/plphys/kiaa029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 10/28/2020] [Indexed: 05/11/2023]
Abstract
Sugar supply is a key component of hypoxia tolerance and acclimation in plants. However, a striking gap remains in our understanding of mechanisms governing sugar impacts on low-oxygen responses. Here, we used a maize (Zea mays) root-tip system for precise control of sugar and oxygen levels. We compared responses to oxygen (21 and 0.2%) in the presence of abundant versus limited glucose supplies (2.0 and 0.2%). Low-oxygen reconfigured the transcriptome with glucose deprivation enhancing the speed and magnitude of gene induction for core anaerobic proteins (ANPs). Sugar supply also altered profiles of hypoxia-responsive genes carrying G4 motifs (sources of regulatory quadruplex structures), revealing a fast, sugar-independent class followed more slowly by feast-or-famine-regulated G4 genes. Metabolite analysis showed that endogenous sugar levels were maintained by exogenous glucose under aerobic conditions and demonstrated a prominent capacity for sucrose re-synthesis that was undetectable under hypoxia. Glucose abundance had distinctive impacts on co-expression networks associated with ANPs, altering network partners and aiding persistence of interacting networks under prolonged hypoxia. Among the ANP networks, two highly interconnected clusters of genes formed around Pyruvate decarboxylase 3 and Glyceraldehyde-3-phosphate dehydrogenase 4. Genes in these clusters shared a small set of cis-regulatory elements, two of which typified glucose induction. Collective results demonstrate specific, previously unrecognized roles of sugars in low-oxygen responses, extending from accelerated onset of initial adaptive phases by starvation stress to maintenance and modulation of co-expression relationships by carbohydrate availability.
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Affiliation(s)
- Maria-Angelica Sanclemente
- Plant Molecular and Cellular Biology, University of Florida, Gainesville, Florida 32611, USA
- Horticultural Sciences, University of Florida, Gainesville, Florida 32611, USA
- Plant Ecophysiology, Institute of Environmental Biology, Utrecht University, Utrecht 3584CH, The Netherlands
- Author for communication:
| | - Fangfang Ma
- Plant Molecular and Cellular Biology, University of Florida, Gainesville, Florida 32611, USA
- Horticultural Sciences, University of Florida, Gainesville, Florida 32611, USA
- Horticultural Sciences, Shandong Agricultural University, Taian, Shandong, China
| | - Peng Liu
- Plant Molecular and Cellular Biology, University of Florida, Gainesville, Florida 32611, USA
- Horticultural Sciences, University of Florida, Gainesville, Florida 32611, USA
- Donald Danforth Plant Science Center, St. Louis, Missouri 63132, USA
| | - Adriana Della Porta
- Plant Molecular and Cellular Biology, University of Florida, Gainesville, Florida 32611, USA
| | - Jugpreet Singh
- Plant Molecular and Cellular Biology, University of Florida, Gainesville, Florida 32611, USA
- Horticultural Sciences, University of Florida, Gainesville, Florida 32611, USA
| | - Shan Wu
- Plant Molecular and Cellular Biology, University of Florida, Gainesville, Florida 32611, USA
| | - Thomas Colquhoun
- Plant Molecular and Cellular Biology, University of Florida, Gainesville, Florida 32611, USA
- Environmental Horticulture, University of Florida, Gainesville, Florida, USA
| | - Timothy Johnson
- Plant Molecular and Cellular Biology, University of Florida, Gainesville, Florida 32611, USA
- Environmental Horticulture, University of Florida, Gainesville, Florida, USA
| | - Jiahn-Chou Guan
- Horticultural Sciences, University of Florida, Gainesville, Florida 32611, USA
| | - Karen E Koch
- Plant Molecular and Cellular Biology, University of Florida, Gainesville, Florida 32611, USA
- Horticultural Sciences, University of Florida, Gainesville, Florida 32611, USA
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10
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Marcon C, Altrogge L, Win YN, Stöcker T, Gardiner JM, Portwood JL, Opitz N, Kortz A, Baldauf JA, Hunter CT, McCarty DR, Koch KE, Schoof H, Hochholdinger F. BonnMu: A Sequence-Indexed Resource of Transposon-Induced Maize Mutations for Functional Genomics Studies. Plant Physiol 2020; 184:620-631. [PMID: 32769162 PMCID: PMC7536688 DOI: 10.1104/pp.20.00478] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 07/27/2020] [Indexed: 05/18/2023]
Abstract
Sequence-indexed insertional libraries in maize (Zea mays) are fundamental resources for functional genetics studies. Here, we constructed a Mutator (Mu) insertional library in the B73 inbred background designated BonnMu A total of 1,152 Mu-tagged F2-families were sequenced using the Mu-seq approach. We detected 225,936 genomic Mu insertion sites and 41,086 high quality germinal Mu insertions covering 16,392 of the annotated maize genes (37% of the B73v4 genome). On average, each F2-family of the BonnMu libraries captured 37 germinal Mu insertions in genes of the Filtered Gene Set (FGS). All BonnMu insertions and phenotypic seedling photographs of Mu-tagged F2-families can be accessed via MaizeGDB.org Downstream examination of 137,410 somatic and germinal insertion sites revealed that 50% of the tagged genes have a single hotspot, targeted by Mu By comparing our BonnMu (B73) data to the UniformMu (W22) library, we identified conserved insertion hotspots between different genetic backgrounds. Finally, the vast majority of BonnMu and UniformMu transposons was inserted near the transcription start site of genes. Remarkably, 75% of all BonnMu insertions were in closer proximity to the transcription start site (distance: 542 bp) than to the start codon (distance: 704 bp), which corresponds to open chromatin, especially in the 5' region of genes. Our European sequence-indexed library of Mu insertions provides an important resource for functional genetics studies of maize.
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Affiliation(s)
- Caroline Marcon
- Institute of Crop Science and Resource Conservation, Crop Functional Genomics, University of Bonn, 53113 Bonn, Germany
| | - Lena Altrogge
- Institute of Crop Science and Resource Conservation, Crop Bioinformatics, University of Bonn, 53115 Bonn, Germany
| | - Yan Naing Win
- Institute of Crop Science and Resource Conservation, Crop Functional Genomics, University of Bonn, 53113 Bonn, Germany
| | - Tyll Stöcker
- Institute of Crop Science and Resource Conservation, Crop Bioinformatics, University of Bonn, 53115 Bonn, Germany
| | - Jack M Gardiner
- Division of Animal Sciences, University of Missouri, Columbia, Missouri 65211
| | - John L Portwood
- USDA-ARS Corn Insects and Crop Genetics Research Unit, Ames, Iowa 50011
| | - Nina Opitz
- Institute of Crop Science and Resource Conservation, Crop Functional Genomics, University of Bonn, 53113 Bonn, Germany
| | - Annika Kortz
- Institute of Crop Science and Resource Conservation, Crop Functional Genomics, University of Bonn, 53113 Bonn, Germany
| | - Jutta A Baldauf
- Institute of Crop Science and Resource Conservation, Crop Functional Genomics, University of Bonn, 53113 Bonn, Germany
| | - Charles T Hunter
- Horticultural Sciences Department, Plant Molecular and Cellular Biology Program, Genetics Institute, University of Florida, Gainesville, Florida 32611
| | - Donald R McCarty
- Horticultural Sciences Department, Plant Molecular and Cellular Biology Program, Genetics Institute, University of Florida, Gainesville, Florida 32611
| | - Karen E Koch
- Horticultural Sciences Department, Plant Molecular and Cellular Biology Program, Genetics Institute, University of Florida, Gainesville, Florida 32611
| | - Heiko Schoof
- Institute of Crop Science and Resource Conservation, Crop Bioinformatics, University of Bonn, 53115 Bonn, Germany
| | - Frank Hochholdinger
- Institute of Crop Science and Resource Conservation, Crop Functional Genomics, University of Bonn, 53113 Bonn, Germany
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11
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Boehlein SK, Liu P, Webster A, Ribeiro C, Suzuki M, Wu S, Guan JC, Stewart JD, Tracy WF, Settles AM, McCarty DR, Koch KE, Hannah LC, Hennen-Bierwagen TA, Myers AM. Effects of long-term exposure to elevated temperature on Zea mays endosperm development during grain fill. Plant J 2019; 99:23-40. [PMID: 30746832 DOI: 10.1111/tpj.14283] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2018] [Revised: 01/22/2019] [Accepted: 01/23/2019] [Indexed: 05/28/2023]
Abstract
Cereal yields decrease when grain fill proceeds under conditions of prolonged, moderately elevated temperatures. Endosperm-endogenous processes alter both rate and duration of dry weight gain, but underlying mechanisms remain unclear. Heat effects could be mediated by either abnormal, premature cessation of storage compound deposition or accelerated implementation of normal development. This study used controlled environments to isolate temperature as the sole environmental variable during Zea mays kernel-fill, from 12 days after pollination to maturity. Plants subjected to elevated day, elevated night temperatures (38°C day, 28°C night (38/28°C])) or elevated day, normal night (38/17°C), were compared with those from controls grown under normal day and night conditions (28/17°C). Progression of change over time in endosperm tissue was followed to dissect contributions at multiple levels, including transcriptome, metabolome, enzyme activities, product accumulation, and tissue ultrastructure. Integrated analyses indicated that the normal developmental program of endosperm is fully executed under prolonged high-temperature conditions, but at a faster rate. Accelerated development was observed when both day and night temperatures were elevated, but not when daytime temperature alone was increased. Although transcripts for most components of glycolysis and respiration were either upregulated or minimally affected, elevated temperatures decreased abundance of mRNAs related to biosynthesis of starch and storage proteins. Further analysis of 20 central-metabolic enzymes revealed six activities that were reduced under high-temperature conditions, indicating candidate roles in the observed reduction of grain dry weight. Nonetheless, a striking overall resilience of grain filling in the face of elevated temperatures can be attributed to acceleration of normal endosperm development.
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Affiliation(s)
- Susan K Boehlein
- Horticultural Sciences Department, University of Florida, Gainesville, FL, 32611, USA
| | - Peng Liu
- Horticultural Sciences Department, University of Florida, Gainesville, FL, 32611, USA
| | - Ashley Webster
- Department of Agronomy, University of Wisconsin, Madison, WI, 53706, USA
| | - Camila Ribeiro
- Horticultural Sciences Department, University of Florida, Gainesville, FL, 32611, USA
| | - Masaharu Suzuki
- Horticultural Sciences Department, University of Florida, Gainesville, FL, 32611, USA
| | - Shan Wu
- Horticultural Sciences Department, University of Florida, Gainesville, FL, 32611, USA
| | - Jiahn-Chou Guan
- Horticultural Sciences Department, University of Florida, Gainesville, FL, 32611, USA
| | - Jon D Stewart
- Department of Chemistry, University of Florida, Gainesville, FL, 32611, USA
| | - William F Tracy
- Department of Agronomy, University of Wisconsin, Madison, WI, 53706, USA
| | - A Mark Settles
- Horticultural Sciences Department, University of Florida, Gainesville, FL, 32611, USA
| | - Donald R McCarty
- Horticultural Sciences Department, University of Florida, Gainesville, FL, 32611, USA
| | - Karen E Koch
- Horticultural Sciences Department, University of Florida, Gainesville, FL, 32611, USA
| | - Larkin C Hannah
- Horticultural Sciences Department, University of Florida, Gainesville, FL, 32611, USA
| | - Tracie A Hennen-Bierwagen
- Roy J. Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, IA, 50011, USA
| | - Alan M Myers
- Roy J. Carver Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, IA, 50011, USA
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12
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Hunter CT, Saunders JW, Magallanes-Lundback M, Christensen SA, Willett D, Stinard PS, Li QB, Lee K, DellaPenna D, Koch KE. Maize w3 disrupts homogentisate solanesyl transferase (ZmHst) and reveals a plastoquinone-9 independent path for phytoene desaturation and tocopherol accumulation in kernels. Plant J 2018; 93:799-813. [PMID: 29315977 DOI: 10.1111/tpj.13821] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 12/12/2017] [Indexed: 06/07/2023]
Abstract
Maize white seedling 3 (w3) has been used to study carotenoid deficiency for almost 100 years, although the molecular basis of the mutation has remained unknown. Here we show that the w3 phenotype is caused by disruption of the maize gene for homogentisate solanesyl transferase (HST), which catalyzes the first and committed step in plastoquinone-9 (PQ-9) biosynthesis in the plastid. The resulting PQ-9 deficiency prohibits photosynthetic electron transfer and eliminates PQ-9 as an oxidant in the enzymatic desaturation of phytoene during carotenoid synthesis. As a result, light-grown w3 seedlings are albino, deficient in colored carotenoids and accumulate high levels of phytoene. However, despite the absence of PQ-9 for phytoene desaturation, dark-grown w3 seedlings can produce abscisic acid (ABA) and homozygous w3 kernels accumulate sufficient carotenoids to generate ABA needed for seed maturation. The presence of ABA and low levels of carotenoids in w3 nulls indicates that phytoene desaturase is able to use an alternate oxidant cofactor, albeit less efficiently than PQ-9. The observation that tocopherols and tocotrienols are modestly affected in w3 embryos and unaffected in w3 endosperm indicates that, unlike leaves, grain tissues deficient in PQ-9 are not subject to severe photo-oxidative stress. In addition to identifying the molecular basis for the maize w3 mutant, we: (1) show that low levels of phytoene desaturation can occur in w3 seedlings in the absence of PQ-9; and (2) demonstrate that PQ-9 and carotenoids are not required for vitamin E accumulation.
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Affiliation(s)
- Charles T Hunter
- USDA-ARS, Center for Medical, Agricultural and Veterinary Entomology, 1700 SW 23rd Dr, Gainesville, FL 32608, USA
| | - Jonathan W Saunders
- University of Florida, Horticultural Sciences, 2550 Hull Rd, Gainesville, FL 32611, USA
| | - Maria Magallanes-Lundback
- Biochemistry and Molecular Biology, Michigan State University, 603 Wilson Rd, East Lansing, MI 48824, USA
| | - Shawn A Christensen
- USDA-ARS, Center for Medical, Agricultural and Veterinary Entomology, 1700 SW 23rd Dr, Gainesville, FL 32608, USA
| | - Denis Willett
- USDA-ARS, Center for Medical, Agricultural and Veterinary Entomology, 1700 SW 23rd Dr, Gainesville, FL 32608, USA
| | - Philip S Stinard
- USDA-ARS, Maize Genetics Stock Center, 1102 S. Goodwin Ave, Urbana, IL 61801, USA
| | - Qin-Bao Li
- USDA-ARS, Center for Medical, Agricultural and Veterinary Entomology, 1700 SW 23rd Dr, Gainesville, FL 32608, USA
| | - Kwanghee Lee
- University of Connecticut, Plant Science and Landscape Architecture, 1376 Storrs Rd, Storrs, CT 06269, USA
| | - Dean DellaPenna
- Biochemistry and Molecular Biology, Michigan State University, 603 Wilson Rd, East Lansing, MI 48824, USA
| | - Karen E Koch
- University of Florida, Horticultural Sciences, 2550 Hull Rd, Gainesville, FL 32611, USA
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13
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Gabay-Laughnan S, Settles AM, Hannah LC, Porch TG, Becraft PW, McCarty DR, Koch KE, Zhao L, Kamps TL, Chamusco KC, Chase CD. Restorer-of-Fertility Mutations Recovered in Transposon-Active Lines of S Male-Sterile Maize. G3 (Bethesda) 2018; 8:291-302. [PMID: 29167273 PMCID: PMC5765357 DOI: 10.1534/g3.117.300304] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 11/15/2017] [Indexed: 12/19/2022]
Abstract
Mitochondria execute key pathways of central metabolism and serve as cellular sensing and signaling entities, functions that depend upon interactions between mitochondrial and nuclear genetic systems. This is exemplified in cytoplasmic male sterility type S (CMS-S) of Zea mays, where novel mitochondrial open reading frames are associated with a pollen collapse phenotype, but nuclear restorer-of-fertility (restorer) mutations rescue pollen function. To better understand these genetic interactions, we screened Activator-Dissociation (Ac-Ds), Enhancer/Suppressor-mutator (En/Spm), and Mutator (Mu) transposon-active CMS-S stocks to recover new restorer mutants. The frequency of restorer mutations increased in transposon-active stocks compared to transposon-inactive stocks, but most mutants recovered from Ac-Ds and En/Spm stocks were unstable, reverting upon backcrossing to CMS-S inbred lines. However, 10 independent restorer mutations recovered from CMS-S Mu transposon stocks were stable upon backcrossing. Many restorer mutations condition seed-lethal phenotypes that provide a convenient test for allelism. Eight such mutants recovered in this study included one pair of allelic mutations that were also allelic to the previously described rfl2-1 mutant. Targeted analysis of mitochondrial proteins by immunoblot identified two features that consistently distinguished restored CMS-S pollen from comparably staged, normal-cytoplasm, nonmutant pollen: increased abundance of nuclear-encoded alternative oxidase relative to mitochondria-encoded cytochrome oxidase and decreased abundance of mitochondria-encoded ATP synthase subunit 1 compared to nuclear-encoded ATP synthase subunit 2. CMS-S restorer mutants thus revealed a metabolic plasticity in maize pollen, and further study of these mutants will provide new insights into mitochondrial functions that are critical to pollen and seed development.
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Affiliation(s)
| | - A Mark Settles
- Horticultural Sciences Department, University of Florida, Gainesville, Florida 32611
| | - L Curtis Hannah
- Horticultural Sciences Department, University of Florida, Gainesville, Florida 32611
| | - Timothy G Porch
- Horticultural Sciences Department, University of Florida, Gainesville, Florida 32611
- Tropical Agriculture Research Station, The United States Department of Agriculture, Agriculture Research Service, Mayaguez, Puerto Rico 00680-5470
| | - Philip W Becraft
- Horticultural Sciences Department, University of Florida, Gainesville, Florida 32611
- Department of Genetics, Development, and Cell Biology, Iowa State University, Ames, Iowa 50011
- Department of Agronomy, Iowa State University, Ames, Iowa 50011
| | - Donald R McCarty
- Horticultural Sciences Department, University of Florida, Gainesville, Florida 32611
| | - Karen E Koch
- Horticultural Sciences Department, University of Florida, Gainesville, Florida 32611
| | - Liming Zhao
- Horticultural Sciences Department, University of Florida, Gainesville, Florida 32611
- Florida Medical Entomology Laboratory, Vero Beach, Florida 32962
| | - Terry L Kamps
- Horticultural Sciences Department, University of Florida, Gainesville, Florida 32611
- Biology Department, New Jersey City University, Jersey City, NJ 07305
| | - Karen C Chamusco
- Horticultural Sciences Department, University of Florida, Gainesville, Florida 32611
| | - Christine D Chase
- Horticultural Sciences Department, University of Florida, Gainesville, Florida 32611
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14
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Affiliation(s)
- Peng Liu
- Horticultural Sciences Department and Plant Molecular and Cellular Biology Program, University of Florida Gainesville Florida
| | - Donald R. McCarty
- Horticultural Sciences Department and Plant Molecular and Cellular Biology Program, University of Florida Gainesville Florida
| | - Karen E. Koch
- Horticultural Sciences Department and Plant Molecular and Cellular Biology Program, University of Florida Gainesville Florida
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15
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Giuseppe POD, Santos MLD, Sousa SMD, Koch KE, Yunes JA, Aparicio R, Murakami MT. A comparative structural analysis reveals distinctive features of co-factor binding and substrate specificity in plant aldo-keto reductases. Biochem Biophys Res Commun 2016; 474:696-701. [PMID: 27154221 DOI: 10.1016/j.bbrc.2016.05.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 05/02/2016] [Indexed: 11/15/2022]
Abstract
Plant aldo-keto reductases of the AKR4C subfamily play key roles during stress and are attractive targets for developing stress-tolerant crops. However, these AKR4Cs show little to no activity with previously-envisioned sugar substrates. We hypothesized a structural basis for the distinctive cofactor binding and substrate specificity of these plant enzymes. To test this, we solved the crystal structure of a novel AKR4C subfamily member, the AKR4C7 from maize, in the apo form and in complex with NADP(+). The binary complex revealed an intermediate state of cofactor binding that preceded closure of Loop B, and also indicated that conformational changes upon substrate binding are required to induce a catalytically-favorable conformation of the active-site pocket. Comparative structural analyses of homologues (AKR1B1, AKR4C8 and AKR4C9) showed that evolutionary redesign of plant AKR4Cs weakened interactions that stabilize the closed conformation of Loop B. This in turn decreased cofactor affinity and altered configuration of the substrate-binding site. We propose that these structural modifications contribute to impairment of sugar reductase activity in favor of other substrates in the plant AKR4C subgroup, and that catalysis involves a three-step process relevant to other AKRs.
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Affiliation(s)
- Priscila Oliveira de Giuseppe
- Biosciences National Laboratory (LNBio), National Center for Research in Energy and Materials (CNPEM), Campinas, SP, Brazil
| | - Marcelo Leite Dos Santos
- Laboratory of Structural Biology and Crystallography, Institute of Chemistry, University of Campinas, Campinas, SP, Brazil
| | | | - Karen E Koch
- Department of Horticultural Science, University of Florida, Gainesville, FL, USA
| | - José Andrés Yunes
- Centro Infantil Boldrini, Campinas, SP, Brazil; Department of Medical Genetics, Faculty of Medical Sciences, University of Campinas, Campinas, SP, Brazil
| | - Ricardo Aparicio
- Laboratory of Structural Biology and Crystallography, Institute of Chemistry, University of Campinas, Campinas, SP, Brazil.
| | - Mario Tyago Murakami
- Biosciences National Laboratory (LNBio), National Center for Research in Energy and Materials (CNPEM), Campinas, SP, Brazil.
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16
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Andorf CM, Kopylov M, Dobbs D, Koch KE, Stroupe ME, Lawrence CJ, Bass HW. G-Quadruplex (G4) Motifs in the Maize (Zea mays L.) Genome Are Enriched at Specific Locations in Thousands of Genes Coupled to Energy Status, Hypoxia, Low Sugar, and Nutrient Deprivation. J Genet Genomics 2014; 41:627-47. [DOI: 10.1016/j.jgg.2014.10.004] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2014] [Revised: 10/16/2014] [Accepted: 10/24/2014] [Indexed: 02/07/2023]
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17
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Hunter CT, Suzuki M, Saunders J, Wu S, Tasi A, McCarty DR, Koch KE. Phenotype to genotype using forward-genetic Mu-seq for identification and functional classification of maize mutants. Front Plant Sci 2014; 4:545. [PMID: 24432026 PMCID: PMC3882665 DOI: 10.3389/fpls.2013.00545] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Accepted: 12/12/2013] [Indexed: 05/08/2023]
Abstract
In pursuing our long-term goals of identifying causal genes for mutant phenotypes in maize, we have developed a new, phenotype-to-genotype approach for transposon-based resources, and used this to identify candidate genes that co-segregate with visible kernel mutants. The strategy incorporates a redesigned Mu-seq protocol (sequence-based, transposon mapping) for high-throughput identification of individual plants carrying Mu insertions. Forward-genetic Mu-seq also involves a genetic pipeline for generating families that segregate for mutants of interest, and grid designs for concurrent analysis of genotypes in multiple families. Critically, this approach not only eliminates gene-specific PCR genotyping, but also profiles all Mu-insertions in hundreds of individuals simultaneously. Here, we employ this scalable approach to study 12 families that showed Mendelian segregation of visible seed mutants. These families were analyzed in parallel, and 7 showed clear co-segregation between the selected phenotype and a Mu insertion in a specific gene. Results were confirmed by PCR. Mutant genes that associated with kernel phenotypes include those encoding: a new allele of Whirly1 (a transcription factor with high affinity for organellar and single-stranded DNA), a predicted splicing factor with a KH domain, a small protein with unknown function, a putative mitochondrial transcription-termination factor, and three proteins with pentatricopeptide repeat domains (predicted mitochondrial). Identification of such associations allows mutants to be prioritized for subsequent research based on their functional annotations. Forward-genetic Mu-seq also allows a systematic dissection of mutant classes with similar phenotypes. In the present work, a high proportion of kernel phenotypes were associated with mutations affecting organellar gene transcription and processing, highlighting the importance and non-redundance of genes controlling these aspects of seed development.
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Affiliation(s)
- Charles T. Hunter
- *Correspondence: Charles T. Hunter, Horticultural Sciences, University of Florida, 2550 Hull Rd., Gainesville, FL 32611, USA e-mail:
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Bihmidine S, Hunter CT, Johns CE, Koch KE, Braun DM. Regulation of assimilate import into sink organs: update on molecular drivers of sink strength. Front Plant Sci 2013; 4:177. [PMID: 23761804 PMCID: PMC3671192 DOI: 10.3389/fpls.2013.00177] [Citation(s) in RCA: 139] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 05/17/2013] [Indexed: 05/18/2023]
Abstract
Recent developments have altered our view of molecular mechanisms that determine sink strength, defined here as the capacity of non-photosynthetic structures to compete for import of photoassimilates. We review new findings from diverse systems, including stems, seeds, flowers, and fruits. An important advance has been the identification of new transporters and facilitators with major roles in the accumulation and equilibration of sugars at a cellular level. Exactly where each exerts its effect varies among systems. Sugarcane and sweet sorghum stems, for example, both accumulate high levels of sucrose, but may do so via different paths. The distinction is central to strategies for targeted manipulation of sink strength using transporter genes, and shows the importance of system-specific analyses. Another major advance has been the identification of deep hypoxia as a feature of normal grain development. This means that molecular drivers of sink strength in endosperm operate in very low oxygen levels, and under metabolic conditions quite different than previously assumed. Successful enhancement of sink strength has nonetheless been achieved in grains by up-regulating genes for starch biosynthesis. Additionally, our understanding of sink strength is enhanced by awareness of the dual roles played by invertases (INVs), not only in sucrose metabolism, but also in production of the hexose sugar signals that regulate cell cycle and cell division programs. These contributions of INV to cell expansion and division prove to be vital for establishment of young sinks ranging from flowers to fruit. Since INV genes are themselves sugar-responsive "feast genes," they can mediate a feed-forward enhancement of sink strength when assimilates are abundant. Greater overall productivity and yield have thus been attained in key instances, indicating that even broader enhancements may be achievable as we discover the detailed molecular mechanisms that drive sink strength in diverse systems.
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Affiliation(s)
- Saadia Bihmidine
- Division of Biological Sciences, University of MissouriColumbia, MO, USA
- Interdisciplinary Plant Group, University of MissouriColumbia, MO, USA
- Missouri Maize Center, University of MissouriColumbia, MO, USA
| | - Charles T. Hunter
- Horticultural Sciences Department, University of FloridaGainesville, FL, USA
- Plant Molecular and Cellular Biology Program, University of FloridaGainesville, FL, USA
| | - Christine E. Johns
- Horticultural Sciences Department, University of FloridaGainesville, FL, USA
- Plant Molecular and Cellular Biology Program, University of FloridaGainesville, FL, USA
| | - Karen E. Koch
- Horticultural Sciences Department, University of FloridaGainesville, FL, USA
- Plant Molecular and Cellular Biology Program, University of FloridaGainesville, FL, USA
| | - David M. Braun
- Division of Biological Sciences, University of MissouriColumbia, MO, USA
- Interdisciplinary Plant Group, University of MissouriColumbia, MO, USA
- Missouri Maize Center, University of MissouriColumbia, MO, USA
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19
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Abstract
The UniformMu transposon population is a large public resource for reverse genetics and functional genomics of maize. Users access the collection of UniformMu genetic stocks that are freely distributed by the Maize Cooperation Stock Center using online tools maintained at MaizeGDB.org. Genetic and molecular analyses of UniformMu stocks (UFMu insertion lines) typically require development of genotyping assays that use a gene-specific polymerase chain reaction (PCR) to follow segregation of transposon insertions in genes of interest. Here we describe methods for accessing the resource and recommended protocols for genotyping of transposon insertion alleles.
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Affiliation(s)
- Donald R McCarty
- Horticultural Sciences Department, Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, FL, USA
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Guan JC, Koch KE, Suzuki M, Wu S, Latshaw S, Petruff T, Goulet C, Klee HJ, McCarty DR. Diverse roles of strigolactone signaling in maize architecture and the uncoupling of a branching-specific subnetwork. Plant Physiol 2012; 160:1303-17. [PMID: 22961131 PMCID: PMC3490586 DOI: 10.1104/pp.112.204503] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2012] [Accepted: 09/01/2012] [Indexed: 05/18/2023]
Abstract
Strigolactones (SLs) control lateral branching in diverse species by regulating transcription factors orthologous to Teosinte branched1 (Tb1). In maize (Zea mays), however, selection for a strong central stalk during domestication is attributed primarily to the Tb1 locus, leaving the architectural roles of SLs unclear. To determine how this signaling network is altered in maize, we first examined effects of a knockout mutation in an essential SL biosynthetic gene that encodes CAROTENOID CLEAVAGE DIOXYGENASE8 (CCD8), then tested interactions between SL signaling and Tb1. Comparative genome analysis revealed that maize depends on a single CCD8 gene (ZmCCD8), unlike other panicoid grasses that have multiple CCD8 paralogs. Function of ZmCCD8 was confirmed by transgenic complementation of Arabidopsis (Arabidopsis thaliana) max4 (ccd8) and by phenotypic rescue of the maize mutant (zmccd8::Ds) using a synthetic SL (GR24). Analysis of the zmccd8 mutant revealed a modest increase in branching that contrasted with prominent pleiotropic changes that include (1) marked reduction in stem diameter, (2) reduced elongation of internodes (independent of carbon supply), and (3) a pronounced delay in development of the centrally important, nodal system of adventitious roots. Analysis of the tb1 zmccd8 double mutant revealed that Tb1 functions in an SL-independent subnetwork that is not required for the other diverse roles of SL in development. Our findings indicate that in maize, uncoupling of the Tb1 subnetwork from SL signaling has profoundly altered the balance between conserved roles of SLs in branching and diverse aspects of plant architecture.
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Affiliation(s)
- Jiahn Chou Guan
- Horticultural Sciences Department, Plant Molecular and Cellular Biology Program, and Genetics Institute, University of Florida, Gainesville, Florida, USA.
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21
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Hunter CT, Kirienko DH, Sylvester AW, Peter GF, McCarty DR, Koch KE. Cellulose Synthase-Like D1 is integral to normal cell division, expansion, and leaf development in maize. Plant Physiol 2012; 158:708-24. [PMID: 22123901 PMCID: PMC3271761 DOI: 10.1104/pp.111.188466] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Accepted: 11/26/2011] [Indexed: 05/03/2023]
Abstract
The Cellulose Synthase-Like D (CslD) genes have important, although still poorly defined, roles in cell wall formation. Here, we show an unexpected involvement of CslD1 from maize (Zea mays) in cell division. Both division and expansion were altered in the narrow-organ and warty phenotypes of the csld1 mutants. Leaf width was reduced by 35%, due mainly to a 47% drop in the number of cell files across the blade. Width of other organs was also proportionally reduced. In leaf epidermis, the deficiency in lateral divisions was only partially compensated by a modest, uniform increase in cell width. Localized clusters of misdivided epidermal cells also led to the formation of warty lesions, with cell clusters bulging from the epidermal layer, and some cells expanding to volumes 75-fold greater than normal. The decreased cell divisions and localized epidermal expansions were not associated with detectable changes in the cell wall composition of csld1 leaf blades or epidermal peels, yet a greater abundance of thin, dense walls was indicated by high-resolution x-ray tomography of stems. Cell-level defects leading to wart formation were traced to sites of active cell division and expansion at the bases of leaf blades, where cytokinesis and cross-wall formation were disrupted. Flow cytometry confirmed a greater frequency of polyploid cells in basal zones of leaf blades, consistent with the disruption of cytokinesis and/or the cell cycle in csld1 mutants. Collectively, these data indicate a previously unrecognized role for CSLD activity in plant cell division, especially during early phases of cross-wall formation.
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Affiliation(s)
- Charles T Hunter
- Horticultural Sciences, University of Florida, Gainesville, Florida 32611, USA.
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Cannon EKS, Birkett SM, Braun BL, Kodavali S, Jennewein DM, Yilmaz A, Antonescu V, Antonescu C, Harper LC, Gardiner JM, Schaeffer ML, Campbell DA, Andorf CM, Andorf D, Lisch D, Koch KE, McCarty DR, Quackenbush J, Grotewold E, Lushbough CM, Sen TZ, Lawrence CJ. POPcorn: An Online Resource Providing Access to Distributed and Diverse Maize Project Data. Int J Plant Genomics 2011; 2011:923035. [PMID: 22253616 PMCID: PMC3255282 DOI: 10.1155/2011/923035] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Accepted: 11/29/2011] [Indexed: 05/21/2023]
Abstract
The purpose of the online resource presented here, POPcorn (Project Portal for corn), is to enhance accessibility of maize genetic and genomic resources for plant biologists. Currently, many online locations are difficult to find, some are best searched independently, and individual project websites often degrade over time-sometimes disappearing entirely. The POPcorn site makes available (1) a centralized, web-accessible resource to search and browse descriptions of ongoing maize genomics projects, (2) a single, stand-alone tool that uses web Services and minimal data warehousing to search for sequence matches in online resources of diverse offsite projects, and (3) a set of tools that enables researchers to migrate their data to the long-term model organism database for maize genetic and genomic information: MaizeGDB. Examples demonstrating POPcorn's utility are provided herein.
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Affiliation(s)
- Ethalinda K. S. Cannon
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
| | - Scott M. Birkett
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
| | - Bremen L. Braun
- USDA-ARS Corn Insects and Crop Genetics Research Unit, Iowa State University, Ames, IA 50011, USA
| | - Sateesh Kodavali
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
| | - Douglas M. Jennewein
- Department of Computer Science, University of South Dakota, Vermillion, SD 57069, USA
| | - Alper Yilmaz
- Plant Biotechnology Center and Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
| | - Valentin Antonescu
- Department of Biostatistics and Computational Biology and Department of Cancer Biology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Sm822, Boston, MA 02215, USA
| | - Corina Antonescu
- Department of Biostatistics and Computational Biology and Department of Cancer Biology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Sm822, Boston, MA 02215, USA
| | - Lisa C. Harper
- USDA-ARS Corn Insects and Crop Genetics Research Unit, Iowa State University, Ames, IA 50011, USA
- USDA-ARS Plant Gene Expression Center, Albany, CA 94710, USA
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Jack M. Gardiner
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
- School of Plant Sciences, University of Arizona, Tucson, AZ 85721, USA
| | - Mary L. Schaeffer
- USDA-ARS Plant Genetics Research Unit, University of Missouri, Columbia, MO 65211, USA
- Division of Plant Sciences, Department of Agronomy, University of Missouri, Columbia, MO 65211, USA
| | - Darwin A. Campbell
- USDA-ARS Corn Insects and Crop Genetics Research Unit, Iowa State University, Ames, IA 50011, USA
| | - Carson M. Andorf
- USDA-ARS Corn Insects and Crop Genetics Research Unit, Iowa State University, Ames, IA 50011, USA
| | - Destri Andorf
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
| | - Damon Lisch
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA
| | - Karen E. Koch
- Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA
| | - Donald R. McCarty
- Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA
| | - John Quackenbush
- Department of Biostatistics and Computational Biology and Department of Cancer Biology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Sm822, Boston, MA 02215, USA
| | - Erich Grotewold
- Plant Biotechnology Center and Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
| | - Carol M. Lushbough
- Department of Computer Science, University of South Dakota, Vermillion, SD 57069, USA
| | - Taner Z. Sen
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
- USDA-ARS Corn Insects and Crop Genetics Research Unit, Iowa State University, Ames, IA 50011, USA
| | - Carolyn J. Lawrence
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
- USDA-ARS Corn Insects and Crop Genetics Research Unit, Iowa State University, Ames, IA 50011, USA
- *Carolyn J. Lawrence:
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Penning BW, Hunter CT, Tayengwa R, Eveland AL, Dugard CK, Olek AT, Vermerris W, Koch KE, McCarty DR, Davis MF, Thomas SR, McCann MC, Carpita NC. Genetic resources for maize cell wall biology. Plant Physiol 2009; 151:1703-28. [PMID: 19926802 PMCID: PMC2785990 DOI: 10.1104/pp.109.136804] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Grass species represent a major source of food, feed, and fiber crops and potential feedstocks for biofuel production. Most of the biomass is contributed by cell walls that are distinct in composition from all other flowering plants. Identifying cell wall-related genes and their functions underpins a fundamental understanding of growth and development in these species. Toward this goal, we are building a knowledge base of the maize (Zea mays) genes involved in cell wall biology, their expression profiles, and the phenotypic consequences of mutation. Over 750 maize genes were annotated and assembled into gene families predicted to function in cell wall biogenesis. Comparative genomics of maize, rice (Oryza sativa), and Arabidopsis (Arabidopsis thaliana) sequences reveal differences in gene family structure between grass species and a reference eudicot species. Analysis of transcript profile data for cell wall genes in developing maize ovaries revealed that expression within families differed by up to 100-fold. When transcriptional analyses of developing ovaries before pollination from Arabidopsis, rice, and maize were contrasted, distinct sets of cell wall genes were expressed in grasses. These differences in gene family structure and expression between Arabidopsis and the grasses underscore the requirement for a grass-specific genetic model for functional analyses. A UniformMu population proved to be an important resource in both forward- and reverse-genetics approaches to identify hundreds of mutants in cell wall genes. A forward screen of field-grown lines by near-infrared spectroscopic screen of mature leaves yielded several dozen lines with heritable spectroscopic phenotypes. Pyrolysis-molecular beam mass spectrometry confirmed that several nir mutants had altered carbohydrate-lignin compositions.
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de Sousa SM, Rosselli LK, Kiyota E, da Silva JC, Souza GHMF, Peroni LA, Stach-Machado DR, Eberlin MN, Souza AP, Koch KE, Arruda P, Torriani IL, Yunes JA. Structural and kinetic characterization of a maize aldose reductase. Plant Physiol Biochem 2009; 47:98-104. [PMID: 19056286 DOI: 10.1016/j.plaphy.2008.10.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2008] [Accepted: 10/19/2008] [Indexed: 05/27/2023]
Abstract
The aldo-keto reductases (AKRs) are classified as oxidoreductases and are found in organisms from prokaryotes to eukaryotes. The AKR superfamily consists of more than 120 proteins that are distributed throughout 14 families. Very few plant AKRs have been characterized and their biological functions remain largely unknown. Previous work suggests that AKRs may participate in stress tolerance by detoxifying reactive aldehyde species. In maize endosperm, the presence of an aldose reductase (AR; EC 1.1.1.21) enzyme has also been hypothesized based on the extensive metabolism of sorbitol. This manuscript identifies and characterizes an AKR from maize (Zea mays L.) with features of an AR. The cDNA clone, classified as AKR4C7, was expressed as a recombinant His-tag fusion protein in Escherichia coli. The product was purified by immobilized metal affinity chromatography followed by anion exchange chromatography. Circular dichroism spectrometry and SAXS analysis indicated that the AKR4C7 protein was stable, remained folded throughout the purification process, and formed monomers of a globular shape, with a molecular envelope similar to human AR. Maize AKR4C7 could utilize dl-glyceraldehyde and some pentoses as substrates. Although the maize AKR4C7 was able to convert sorbitol to glucose, the low affinity for this substrate indicated that AKR4C7 was probably a minimal contributor to sorbitol metabolism in maize seeds. Polyclonal antisera raised against AKR4C7 recognized at least three AR-like polypeptides in maize kernels, consistent with the presence of a small gene family. Diverse functions may have evolved for maize AKRs in association with specific physiological requirements of kernel development.
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Affiliation(s)
- Sylvia Morais de Sousa
- Centro de Biologia Molecular e Engenharia Genética, Departamento de Genética e Evolução, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, SP, Brazil
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Suzuki M, Latshaw S, Sato Y, Settles AM, Koch KE, Hannah LC, Kojima M, Sakakibara H, McCarty DR. The Maize Viviparous8 locus, encoding a putative ALTERED MERISTEM PROGRAM1-like peptidase, regulates abscisic acid accumulation and coordinates embryo and endosperm development. Plant Physiol 2008; 146:1193-206. [PMID: 18203869 PMCID: PMC2259049 DOI: 10.1104/pp.107.114108] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2007] [Accepted: 01/12/2008] [Indexed: 05/18/2023]
Abstract
We describe a mutant of Zea mays isolated from a W22 inbred transposon population, widow's peak mutant1 (wpk1), with an altered pattern of anthocyanin synthesis and aleurone cell differentiation in endosperm. In addition, a failure of the developing mutant embryo to form leaf initials is associated with decreased expression of a subset of meristem regulatory genes that includes Abphyl1 and Td1. We show that the viviparous8 (vp8) mutant has a similar pleiotropic phenotype in the W22 inbred background in contrast to the viviparous embryo phenotype exhibited in the standard genetic background, and we confirmed that wpk1 is allelic to vp8. Further genetic analysis revealed that the standard vp8 stock contains an unlinked, partially dominant suppressor of the vp8 mutation that is not present in W22. Consistent with the early-onset viviparous phenotype of vp8, expression of several embryonic regulators, including LEC1/B3 domain transcription factors, was reduced in the mutant embryo. Moreover, reduced abscisic acid (ABA) content of vp8/wpk1 embryos was correlated with altered regulation of ABA biosynthesis, as well as ABA catabolic pathways. The ABA biosynthetic gene Vp14 was down-regulated in the nonsuppressed background, whereas the ZmABA8'oxA1a ABA 8'-hydroxylase gene was strongly up-regulated in both genetic backgrounds. Molecular analysis revealed that Vp8 encodes a putative peptidase closely related to Arabidopsis thaliana ALTERED MERISTEM PROGRAM1. Because the Vp8 regulates meristem development as well as seed maturation processes, including ABA accumulation, we propose that VP8 is required for synthesis of an unidentified signal that integrates meristem and embryo formation in seeds.
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Affiliation(s)
- Masaharu Suzuki
- Plant Molecular and Cellular Biology Program, Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA.
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26
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Eveland AL, McCarty DR, Koch KE. Transcript profiling by 3'-untranslated region sequencing resolves expression of gene families. Plant Physiol 2008; 146:32-44. [PMID: 18024554 PMCID: PMC2230554 DOI: 10.1104/pp.107.108597] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2007] [Accepted: 10/26/2007] [Indexed: 05/18/2023]
Abstract
Differences in gene expression underlie central questions in plant biology extending from gene function to evolutionary mechanisms and quantitative traits. However, resolving expression of closely related genes (e.g. alleles and gene family members) is challenging on a genome-wide scale due to extensive sequence similarity and frequently incomplete genome sequence data. We present a new expression-profiling strategy that utilizes long-read, high-throughput sequencing to capture the information-rich 3'-untranslated region (UTR) of messenger RNAs (mRNAs). Resulting sequences resolve gene-specific transcripts independent of a sequenced genome. Analysis of approximately 229,000 3'-anchored sequences from maize (Zea mays) ovaries identified 14,822 unique transcripts represented by at least two sequence reads. Total RNA from ovaries of drought-stressed wild-type and viviparous-1 mutant plants was used to construct a multiplex cDNA library. Each sample was labeled by incorporating one of 16 unique three-base key codes into the 3'-cDNA fragments, and combined samples were sequenced using a GS 20 454 instrument. Transcript abundance was quantified by frequency of sequences identifying each unique mRNA. At least 202 unique transcripts showed highly significant differences in abundance between wild-type and mutant samples. For a subset of mRNAs, quantitative differences were validated by real-time reverse transcription-polymerase chain reaction. The 3'-UTR profile resolved 12 unique cellulose synthase (CesA) transcripts in maize ovaries and identified previously uncharacterized members of a histone H1 gene family. In addition, this method resolved nearly identical paralogs, as illustrated by two auxin-repressed, dormancy-associated (Arda) transcripts, which showed reciprocal mRNA abundance in wild-type and mutant samples. Our results demonstrate the potential of 3'-UTR profiling for resolving gene- and allele-specific transcripts.
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Affiliation(s)
- Andrea L Eveland
- Department of Horticultural Sciences, Plant Molecular and Cellular Biology Program, Genetics Institute, University of Florida, Gainesville, FL 32611, USA
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Huang LF, Bocock PN, Davis JM, Koch KE. Regulation of invertase: a 'suite' of transcriptional and post-transcriptional mechanisms. Funct Plant Biol 2007; 34:499-507. [PMID: 32689379 DOI: 10.1071/fp06227] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2006] [Accepted: 01/04/2007] [Indexed: 05/16/2023]
Abstract
Recent evidence indicates that several mechanisms can alter invertase activity and, thus, affect sucrose metabolism and resource allocation in plants. One of these mechanisms is the compartmentalisation of at least some vacuolar invertases in precursor protease vesicles (PPV), where their retention could control timing of delivery to vacuoles and hence activity. PPV are small, ER-derived bodies that sequester a subset of vacuolar-bound proteins (such as invertases and protease precursors) releasing them to acid vacuoles in response to developmental or environmental signals. Another newly-identified effector of invertases is wall-associated kinase 2 (WAK2), which can regulate a specific vacuolar invertase in Arabidopsis (AtvacINV1) and alter root growth when osmolyte supplies are limiting. WAKs are ideally positioned to sense changes in the interface between the cell wall and plasma membrane (such as turgor), because the N-terminus of each WAK extends into the cell wall matrix (where a pectin association is hypothesised) and the C-terminus has a cytoplasmic serine/threonine kinase domain (signalling). Still other avenues of invertase control are provided by a diverse group of kinases and phosphatases, consistent with input from multiple sensing systems for sugars, pathogens, ABA and other hormones. Mechanisms of regulation may also vary for the contrasting sugar responses of different acid invertase transcripts. Some degree of hexokinase involvement and distinctive kinetics have been observed for the sugar-repressed invertases, but not for the more common, sugar-induced forms examined thus far. An additional means of regulation for invertase gene expression lies in the multiple DST (Down STream) elements of the 3' untranslated region for the most rapidly repressed invertases. Similar sequences were initially identified in small auxin-up RNAs (SAUR) where they mediate rapid mRNA turnover. Finally, the invertase inhibitors, cell wall- and vacuolar inhibitors of fructosidase (CIF and VIF, respectively) are indistinguishable by sequence alone from pectin methylesterase inhibitors (PMEI); however, recent evidence suggests binding specificity may be determined by flexibility of a short, N-terminal region. These recently characterised processes increase the suite of regulatory mechanisms by which invertase - and, thus, sucrose metabolism and resource partitioning - can be altered in plants.
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Affiliation(s)
- Li-Fen Huang
- Plant Molecular and Cellular Biology Program, PO BOX 110690, University of Florida, Gainesville, FL 32611, USA
| | - Philip N Bocock
- Plant Molecular and Cellular Biology Program, PO BOX 110690, University of Florida, Gainesville, FL 32611, USA
| | - John M Davis
- Plant Molecular and Cellular Biology Program, PO BOX 110690, University of Florida, Gainesville, FL 32611, USA
| | - Karen E Koch
- Plant Molecular and Cellular Biology Program, PO BOX 110690, University of Florida, Gainesville, FL 32611, USA
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28
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Settles AM, Holding DR, Tan BC, Latshaw SP, Liu J, Suzuki M, Li L, O'Brien BA, Fajardo DS, Wroclawska E, Tseung CW, Lai J, Hunter CT, Avigne WT, Baier J, Messing J, Hannah LC, Koch KE, Becraft PW, Larkins BA, McCarty DR. Sequence-indexed mutations in maize using the UniformMu transposon-tagging population. BMC Genomics 2007; 8:116. [PMID: 17490480 PMCID: PMC1878487 DOI: 10.1186/1471-2164-8-116] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2006] [Accepted: 05/09/2007] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Gene knockouts are a critical resource for functional genomics. In Arabidopsis, comprehensive knockout collections were generated by amplifying and sequencing genomic DNA flanking insertion mutants. These Flanking Sequence Tags (FSTs) map each mutant to a specific locus within the genome. In maize, FSTs have been generated using DNA transposons. Transposable elements can generate unstable insertions that are difficult to analyze for simple knockout phenotypes. Transposons can also generate somatic insertions that fail to segregate in subsequent generations. RESULTS Transposon insertion sites from 106 UniformMu FSTs were tested for inheritance by locus-specific PCR. We confirmed 89% of the FSTs to be germinal transposon insertions. We found no evidence for somatic insertions within the 11% of insertion sites that were not confirmed. Instead, this subset of insertion sites had errors in locus-specific primer design due to incomplete or low-quality genomic sequences. The locus-specific PCR assays identified a knockout of a 6-phosphogluconate dehydrogenase gene that co-segregates with a seed mutant phenotype. The mutant phenotype linked to this knockout generates novel hypotheses about the role for the plastid-localized oxidative pentose phosphate pathway during grain-fill. CONCLUSION We show that FSTs from the UniformMu population identify stable, germinal insertion sites in maize. Moreover, we show that these sequence-indexed mutations can be readily used for reverse genetic analysis. We conclude from these data that the current collection of 1,882 non-redundant insertion sites from UniformMu provide a genome-wide resource for reverse genetics.
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Affiliation(s)
- A Mark Settles
- Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA
| | - David R Holding
- Department of Plant Sciences, University of Arizona, Tucson, AZ 85721, USA
| | - Bao Cai Tan
- Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA
| | - Susan P Latshaw
- Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA
| | - Juan Liu
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
| | - Masaharu Suzuki
- Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA
| | - Li Li
- Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA
| | - Brent A O'Brien
- Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA
| | - Diego S Fajardo
- Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA
| | - Ewa Wroclawska
- Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA
| | - Chi-Wah Tseung
- Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA
| | - Jinsheng Lai
- Waksman Institute, Rutgers University, Piscataway, NJ 08854, USA
| | - Charles T Hunter
- Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA
| | - Wayne T Avigne
- Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA
| | - John Baier
- Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA
| | - Joachim Messing
- Waksman Institute, Rutgers University, Piscataway, NJ 08854, USA
| | - L Curtis Hannah
- Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA
| | - Karen E Koch
- Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA
| | - Philip W Becraft
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
| | - Brian A Larkins
- Department of Plant Sciences, University of Arizona, Tucson, AZ 85721, USA
| | - Donald R McCarty
- Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA
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McCarty DR, Settles AM, Suzuki M, Tan BC, Latshaw S, Porch T, Robin K, Baier J, Avigne W, Lai J, Messing J, Koch KE, Hannah LC. Steady-state transposon mutagenesis in inbred maize. Plant J 2005; 44:52-61. [PMID: 16167895 DOI: 10.1111/j.1365-313x.2005.02509.x] [Citation(s) in RCA: 170] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
We implement a novel strategy for harnessing the power of high-copy transposons for functional analysis of the maize genome, and report behavioral features of the Mutator system in a uniform inbred background. The unique UniformMu population and database facilitate high-throughput molecular analysis of Mu-tagged mutants and gene knockouts. Key features of the population include: (i) high mutation frequencies (7% independent seed mutations) and moderation of copy number (approximately 57 total Mu elements; 1-2 MuDR copies per plant) were maintained by continuous back-crossing into a phenotypically uniform inbred background; (ii) a bz1-mum9 marker enabled selection of stable lines (loss of MuDR), inhibiting further transpositions in lines selected for molecular analysis; (iii) build-up of mutation load was prevented by screening Mu-active parents to exclude plants carrying pre-existing seed mutations. To create a database of genomic sequences flanking Mu insertions, selected mutant lines were analyzed by sequencing of MuTAIL PCR clone libraries. These sequences were annotated and clustered to facilitate bioinformatic subtraction of ancestral elements and identification of insertions unique to mutant lines. New insertions targeted low-copy, gene-rich sequences, and in silico mapping revealed a random distribution of insertions over the genome. Our results indicate that Mu populations differ markedly in the occurrence of Mu insertion hotspots and the frequency of suppressible mutations. We suggest that controlled MuDR copy number in UniformMu lines is a key determinant of these differences. The public database (http://uniformmu.org; http://endosperm.info) includes pedigree and phenotypic data for over 2000 independent seed mutants selected from a population of 31 548 F2 lines and integrated with analyses of 34 255 MuTAIL sequences.
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Affiliation(s)
- Donald R McCarty
- Plant Molecular and Cellular Biology Program, Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA.
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Yong W, Link B, O'Malley R, Tewari J, Hunter CT, Lu CA, Li X, Bleecker AB, Koch KE, McCann MC, McCarty DR, Patterson SE, Reiter WD, Staiger C, Thomas SR, Vermerris W, Carpita NC. Genomics of plant cell wall biogenesis. Planta 2005; 221:747-51. [PMID: 15981004 DOI: 10.1007/s00425-005-1563-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2004] [Accepted: 04/01/2005] [Indexed: 05/03/2023]
Affiliation(s)
- Weidong Yong
- Department of Botany and Plant Pathology, Purdue University, 915 West State Street, West Lafayette, Indiana, 47907-2054, USA
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Wächter R, Langhans M, Aloni R, Götz S, Weilmünster A, Koops A, Temguia L, Mistrik I, Pavlovkin J, Rascher U, Schwalm K, Koch KE, Ullrich CI. Vascularization, high-volume solution flow, and localized roles for enzymes of sucrose metabolism during tumorigenesis by Agrobacterium tumefaciens. Plant Physiol 2003; 133:1024-37. [PMID: 14526106 PMCID: PMC281599 DOI: 10.1104/pp.103.028142] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2003] [Revised: 07/14/2003] [Accepted: 07/27/2003] [Indexed: 05/20/2023]
Abstract
Vascular differentiation and epidermal disruption are associated with establishment of tumors induced by Agrobacterium tumefaciens. Here, we address the relationship of these processes to the redirection of nutrient-bearing water flow and carbohydrate delivery for tumor growth within the castor bean (Ricinus communis) host. Treatment with aminoethoxyvinyl-glycine showed that vascular differentiation and epidermal disruption were central to ethylene-dependent tumor establishment. CO2 release paralleled tumor growth, but water flow increased dramatically during the first 3 weeks. However, tumor water loss contributed little to water flow to host shoots. Tumor water loss was followed by accumulation of the osmoprotectants, sucrose (Suc) and proline, in the tumor periphery, shifting hexose-to-Suc balance in favor of sugar signals for maturation and desiccation tolerance. Concurrent activities and sites of action for enzymes of Suc metabolism changed: Vacuolar invertase predominated during initial import of Suc into the symplastic continuum, corresponding to hexose concentrations in expanding tumors. Later, Suc synthase (SuSy) and cell wall invertase rose in the tumor periphery to modulate both Suc accumulation and descending turgor for import by metabolization. Sites of abscisic acid immunolocalization correlated with both central vacuolar invertase and peripheral cell wall invertase. Vascular roles were indicated by SuSy immunolocalization in xylem parenchyma for inorganic nutrient uptake and in phloem, where resolution allowed SuSy identification in sieve elements and companion cells, which has widespread implications for SuSy function in transport. Together, data indicate key roles for ethylene-dependent vascularization and cuticular disruption in the redirection of water flow and carbohydrate transport for successful tumor establishment.
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Affiliation(s)
- Rebecca Wächter
- Institute of Botany, Darmstadt University of Technology, Schnittspahnstrasse 3, 64287 Darmstadt, Germany
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Abstract
BACKGROUND Improving clinical outcomes requires that physicians examine and change their clinical practice. Sustaining outcome improvements requires a dedicated and dynamic program of analyzing and improving patient care. In 1992 North Mississippi Health Services (NMHS) implemented a program to improve physicians' clinical efficiency. CLINICAL PRACTICE ANALYSIS ( CPA): CPA uses evidenced-based guidelines and examines each physician's resource utilization, processes, and outcomes for a diagnosis or procedure. Clinical practice profiles are developed, and individual performance is compared to local and national benchmarks and presented to physicians. The CPA process is used on its own or as a component of more comprehensive performance improvements projects. Physicians have been engaged in outcome improvement by more than 55 CPA projects. RESULTS NHMS has progressively reduced its Medicare loss and its length of stay (LOS) to 4.9 days. Mortality and readmission rates have been reduced in specific diagnoses. The community-acquired pneumonia project reduced the LOS from 7.7 to 5.1 days, decreaesed the mortality rate from 8.9% to 5.0%, and decreased the cost of care from $4,269 to $3,834. The ischemic stroke project reduced the aspiration pneumonia rate from 6.4% to 0% and mortality from 11.0% to 4.6%. Patients' average LOS decreased from 10.7 days to 6.5 days, and their cost of care was reduced by $1,100 per patient. DISCUSSION Providing individualized data has engaged physicians in improving outcomes. The program has evolved from improving efficiency to managing outcomes and from simple CPA projects to integrated performance improvement projects; however, the CPA process remains the cornerstone of the current process.
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Affiliation(s)
- J Englert
- North Mississippi Health Services, 830 South Gloster Street, Tupelo, MS 38801, USA.
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Abstract
PURPOSE Previous studies have examined the effects of hospitalists in urban academic hospitals. We compared the outcomes of patients treated by hospitalists with those of patients treated by internists at a 647-bed rural community hospital. SUBJECTS AND METHODS The 443 patients in the hospitalists' 10 most common diagnosis-related groups (DRGs) were compared with 1,681 patients in the same DRGs who were cared for by internists in fiscal year 1998. Length of stay, cost of care, patient illness severity, patient satisfaction, 30-day readmission rate, inpatient mortality, discharge status, and resource utilization were compared. RESULTS The hospitalists' patients had a shorter mean (+/- SD) length of stay (4.1 +/- 3.0 days versus 5.5 +/- 4.9 days, P <0.001) and their cost of care was less than that of the internists' patients ($4,098 +/- $2,455 versus $4,658 +/- $4,084, P <0.001). Analyses that adjusted for patient age, race, sex, insurance status, severity of illness, and specific medical comorbidities confirmed these differences. The differences between hospitalists and internists were most apparent among very ill patients. Mortality rates were similar (4.5% for hospitalists versus 4.9% for internists, P = 0.80), as were the readmission rates (4.5% for hospitalists versus 5.6% for internists, P = 0.41). Patient satisfaction was similar for both groups. The internists used more resources in 8 of 11 categories. CONCLUSIONS The hospitalists provided cost-effective care, particularly for the sickest patients, with good outcomes and patient satisfaction.
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Affiliation(s)
- K M Davis
- North Mississippi Health Services, Tupelo, Mississippi, USA
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Koch KE, Ying Z, Wu Y, Avigne WT. Multiple paths of sugar-sensing and a sugar/oxygen overlap for genes of sucrose and ethanol metabolism. J Exp Bot 2000; 51 Spec No:417-27. [PMID: 10938850 DOI: 10.1093/jexbot/51.suppl_1.417] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The two-fold purpose of this work is, first, to review current hypotheses for multiple paths of sugar-sensing in an oxygen-responsive context, and second, to present evidence for the extent of sugar/oxygen overlap regulating genes for sucrose and ethanol metabolism. Current data indicate that sugar signals in plants may be initiated by (a) hexokinases, (b) membrane sensors, (c) acetate and/or respiratory metabolites, and (d) other signals and/or crosstalk. Responses may also involve concurrent input along transduction paths by effectors such as energy charge, P status, and phytohormones. Prime candidates for initiation and/or integration of such signal integration include SNF1- and SCF-like, multi-enzyme complexes. In addition, different paths of sugar signal transduction may be linked to contrasting roles of responsive genes during feast, famine or pathogen attack. Oxygen can potentially alter sugar signals at several points, so its influence on feast and famine responses was initially tested with genes for sucrose metabolism in maize root tips. The Sus1 and Sh1 sucrose synthases in maize (typically up-regulated by carbohydrate abundance and deprivation, respectively) showed parallel responses to hypoxia (3% O2 [0.03l l-1 O2]) and anoxia (0% O2 [0l l-1 O2]) that were consistent with involvement of similar signals. In contrast, the differential sugar-responses of the lvr1 and lvr2 invertases were not evident under low oxygen, and both genes were rapidly repressed. A third response was evident in the marked, sugar-regulation of an oxygen-responsive Adh1 gene for alcohol dehydrogenase, which was sensitive to sugar availability from deficit to abundance, regardless of oxygen status (anaerobic to fully aerobic [40% O2 (0.04l l-1 O2)]. A clear interface is thus evident between sugar and oxygen signals, but this varies markedly with the genes involved and probable differences in respective transduction paths.
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Affiliation(s)
- K E Koch
- Horticultural Sciences Department, University of Florida, Gainesville 32611, USA.
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Zeng Y, Wu Y, Avigne WT, Koch KE. Rapid repression of maize invertases by low oxygen. Invertase/sucrose synthase balance, sugar signaling potential, and seedling survival. Plant Physiol 1999; 121:599-608. [PMID: 10517852 PMCID: PMC59423 DOI: 10.1104/pp.121.2.599] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/1999] [Accepted: 07/01/1999] [Indexed: 05/18/2023]
Abstract
We show here that invertase gene expression and the invertase-sucrose (Suc) synthase ratio decrease abruptly in response to low oxygen in maize root tips. In addition to aiding in the conservation of carbon and possibly ATP, this response has the potential to directly affect sugar signaling relative to carbon flux. Experiments were motivated by the potential for a reduced invertase/Suc synthase balance to alter the impact of respiratory and/or membrane carbon flux on sugar signaling. Maize (Zea mays L.) seedlings with 5-cm primary roots were exposed to anoxic (0% [v/v] O2), hypoxic (3% [v/v] O2), and aerobic conditions. Rapid repression of the Ivr1 and Ivr2 maize invertases by low oxygen was evident in root tips within 3 h at both the transcript and activity levels. The speed and extent of this response increased with the degree of oxygen deprivation and differed with genotypes. This decrease in expression also contrasted markedly to that of other genes for respiratory Suc metabolism, such as Suc synthases, which typically increased or remained constant. Although previous work showed that the contrasting effects of sugars on Suc synthase genes were reflected in their regulation by hypoxia and anoxia, the same was not observed for the differentially sugar-responsive invertases. Theoretically advantageous reductions in the invertase/Suc synthase balance thus resulted. However, where this response was extreme (an Oh43 inbred), total sucrolytic capacity dropped below an apparent minimum and root tip viability was reduced. Paradoxically, only Oh43 seedlings showed survival levels >80% (versus <50%) after extreme, long-term stress, suggesting a possible advantage for multiple means of reducing sink activity. Overall, our results demonstrate a rapid change in the regulation and balance of invertases and Suc synthases that could have an immediate impact on limiting the extent of Suc cleavage and reducing the extent of concomitant, hexose-based sugar signaling under low oxygen.
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Affiliation(s)
- Y Zeng
- Plant Molecular and Cellular Biology Program, Horticultural Sciences Department, 1143 Fifield Hall, University of Florida, Gainesville, Florida 32611, USA
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Abstract
The justification for and the training, responsibilities, and contributions of two clinically oriented pharmacy technicians are described. A proposal outlining the clinical services being provided by pharmacists at a 650-bed medical center and the need for technical assistance was developed and approved. Two clinical technician positions were created to replace one of two eliminated pharmacist positions. Each of the technicians hired had worked successfully in several traditional pharmacy technician roles. The technicians were trained for specific roles and cross-trained in the basic functions of each other's roles. The technicians made rounds with the pharmacists to learn how to evaluate patients and interact with physicians and nurses and were required to demonstrate competence in deciding which patients required further evaluation. One technician focuses on providing direct clinical service support, and the other works primarily as a clinical administrative assistant. Half the technicians' time is spent performing services previously performed by pharmacists. In addition, the technicians track outcomes and provide clerical and data-management assistance. The technicians are responsible for screening and tracking approximately 400 patients per month on well-established services and 400 per month on two new monitoring services. The technicians have helped develop a medication-error tracking program. Clinically oriented technicians freed up pharmacists' time by collecting routine clinical data and managing clinical projects; through protocol-based screening and outcomes tracking, the technicians have helped to implement new clinical services and evaluate existing ones.
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Affiliation(s)
- K E Koch
- Pharmacy Department, North Mississippi Medical Center (NMMC), Tupelo 38801, USA
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Abstract
BACKGROUND AND PURPOSE Ischemic stroke is a high-volume and financially draining diagnosis at this rural health system. The purpose of this clinical practice analysis was to identify resource utilization and clinical process inefficiencies and to promote clinically efficient, evidence-based improvements. METHODS A retrospective analysis of medical record and financial databases of 356 patients with ischemic stroke was performed. The medical record data were adjusted for severity, and outliers were eliminated. The resources utilized by each physician were determined. Comparative graphs were prepared, presented, and discussed. The physicians implemented two types of changes: (1) alteration of resource utilization and consultation patterns and (2) support of clinical process improvement. In 1997, a follow-up analysis of 399 patients was performed. RESULTS The initial comparison of internists' to neurologists' patient populations found the following: patient age (75 versus 65 years), patient severity ratings (2.8 versus 2.5), length of stay (10.7 versus 8.8 days), costs ($7360 versus $6862), mortality rates (12.5% versus 8.9%), and aspiration pneumonia rate (8.5% versus 3.8%). A comparison of the 1995 analysis to the 1997 analysis revealed the following per patient resource utilization decreases (all P < 0.05): chemistry laboratory, 2.65 to 1.95 studies; intravenous fluids, 2.85 to 1.85 L; oxygen use, 6.06 to 2.75 U; and nifedipine use, 1.62 to 0.33 capsules. The clinical process improvements resulted in the following overall outcomes (all P < 0.05 except mortality): length of stay (7.2 days), nonadjusted costs ($6246), mortality (6.5%), and rates of pneumonia (2.7%). CONCLUSIONS Objective analysis of resource utilization resulted in physicians changing their individual management of stroke and collectively supporting clinical process changes that improved clinical and financial outcomes.
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Zeng Y, Wu Y, Avigne WT, Koch KE. Differential regulation of sugar-sensitive sucrose synthases by hypoxia and anoxia indicate complementary transcriptional and posttranscriptional responses. Plant Physiol 1998; 116:1573-83. [PMID: 9536076 PMCID: PMC35066 DOI: 10.1104/pp.116.4.1573] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/1997] [Accepted: 01/14/1998] [Indexed: 05/20/2023]
Abstract
The goal of this research was to resolve the hypoxic and anoxic responses of maize (Zea mays) sucrose (Suc) synthases known to differ in their sugar regulation. The two maize Suc synthase genes, Sus1 and Sh1, both respond to sugar and O2, and recent work suggests commonalities between these signaling systems. Maize seedlings (NK508 hybrid, W22 inbred, and an isogenic sh1-null mutant) were exposed to anoxic, hypoxic, and aerobic conditions (0, 3, and 21% O2, respectively), when primary roots had reached approximately 5 cm. One-centimeter tips were excised for analysis during the 48-h treatments. At the mRNA level, Sus1 was rapidly up-regulated by hypoxia (approximately 5-fold in 6 h), whereas anoxia had less effect. In contrast, Sh1 mRNA abundance increased strongly under anoxia (approximately 5-fold in 24 h) and was much less affected by hypoxia. At the enzyme level, total Suc synthase activity rose rapidly under hypoxia but showed little significant change during anoxia. The contributions of SUS1 and SH1 activities to these responses were dissected over time by comparing the sh1-null mutant with the isogenic wild type (Sus+, Sh1+). Sh1-dependent activity contributed most markedly to a rapid protein-level response consistently observed in the first 3 h, and, subsequently, to a long-term change mediated at the level of mRNA accumulation at 48 h. A complementary midterm rise in SUS1 activity varied in duration with genetic background. These data highlight the involvement of distinctly different genes and probable signal mechanisms under hypoxia and anoxia, and together with earlier work, show parallel induction of "feast and famine" Suc synthase genes by hypoxia and anoxia, respectively. In addition, complementary modes of transcriptional and posttranscriptional regulation are implicated by these data, and provide a mechanism for sequential contributions from the Sus1 and Sh1 genes during progressive onset of naturally occurring low-O2 events.
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Affiliation(s)
- Y Zeng
- Plant Molecular and Cellular Biology Program, Horticultural Sciences Department, Fifield Hall, University of Florida, Gainesville, Florida 32611, USA
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40
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Beckham SH, Englert JE, Davis KM, Koch KE. Clinical applications of computer-based health information. Top Health Inf Manage 1998; 18:50-9. [PMID: 10176540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Competitive health care systems are improving their clinical and cost efficiency by performing clinical practice analyses. Large numbers of severity-adjusted cases provide the most objective data for making clinical efficiency decisions. The most cost-effective way to perform these analyses is to utilize well-coded, computer-based health information. This requires consistent coding of patients' comorbidities and complications as well as an interactive working relationship between coders and clinicians providing the clinical practice analysis. The article describes one hospital's evolving clinical efficiency information needs, how its health information system met them, the clinical practice analysis procedure, and the outcomes of this clinical practice analysis.
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Affiliation(s)
- S H Beckham
- North Mississippi Medical Center, Tupelo, MS, USA
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Davis KM, Hill JE, Barber JB, Koch KE. Developing a rural primary care practice network. Manag Care Interface 1997; 10:51-60, 70. [PMID: 10176747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Establishing and managing a primary care practice in rural communities is particularly challenging. Many rural practices are closing, and relatively few new practices are initiated independently. The integrated health system can provide at least part of the solution to the lack of physicians in the rural setting. The following article describes the objectives, methods, and results of an integrated health system's development of a rural primary care provider network.
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Affiliation(s)
- K M Davis
- North Mississippi Health Services, Tupelo, USA
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Lin SZ, Yan GM, Koch KE, Paul SM, Irwin RP. Mastoparan-induced apoptosis of cultured cerebellar granule neurons is initiated by calcium release from intracellular stores. Brain Res 1997; 771:184-95. [PMID: 9401738 DOI: 10.1016/s0006-8993(97)00763-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We have recently reported that mastoparan, a peptide toxin isolated from wasp venom, induces apoptosis in cultured cerebellar granule neurons that can be blocked by cholera toxin, an activator of Gs. Measurements of intracellular free calcium concentration ([Ca2+]i) reveal that mastoparan induces a dramatic elevation of [Ca2+]i that is frequently followed by enhanced leakage of fura-2 out of the neurons, suggesting that this rise in [Ca2+]i may be due to a more generalized change in membrane permeability. However, the mastoparan-induced initial elevation of [Ca2+]i is maintained in the absence of extracellular Ca2+, suggesting that the rise of [Ca2+]i is from intracellular stores. This conclusion is supported by the observation that depletion of [Ca2+]i stores by pretreatment with either caffeine or thapsigargin attenuates both the rise in [Ca2+]i and cell death induced by mastoparan. Phospholipase C (PLC) inhibitors, neomycin and U73122 block mastoparan-induced increases of [Ca2+]i and protect against neuronal death. Pretreatment with cholera toxin, but not pertussis toxin, reduced the mastoparan-induced rise in [Ca2+]i. Taken together, our data suggest that mastoparan initiates cell death in cerebellar granule neurons by inducing Ca2+ release from intracellular stores, probably via activation of PLC and IP3. A secondary or parallel process results in disruption of plasma membrane integrity and may be ultimately responsible for the death of these neurons by mastoparan.
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Affiliation(s)
- S Z Lin
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis 46202-5120, USA
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Abstract
Thyroglossal duct carcinoma is rare, and its presentation is similar to that of a thyroglossal duct cyst: a nontender, palpable mass in the midline location. Rapid increase in growth may be a sign of malignancy, but the diagnosis is based on the pathology of the cyst. Initial treatment of thyroglossal duct carcinoma is the same surgical procedure used for removal of a thyroglossal duct cyst. Further surgery depends on the finding of thyroid nodules or positive lymph nodes but is rarely necessary. The recurrence rate after simple excision is low. Postoperative radioiodine ablation or radiation is considered in cases of recurrence or metastasis. In this report, we describe a patient with a new-onset, nontender, neck mass who had a Sistrunk procedure for a presumed thyroglossal duct cyst and was found to have papillary carcinoma.
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Affiliation(s)
- B R Walton
- Department of Family Medicine, University of Mississippi School of Medicine, Tupelo, USA
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Abstract
The radiation protective effect of thiol compounds is unequivocal and their use is only limited by their toxic effects. We used the principle of alpha alkylation, which renders amino acids unmetabolizable, to reduce the toxicity of homocysteine. This product, alpha-methyl-homocysteine thio-lactone, was tested for toxicity and radiation protective effect along with known protectors L-cysteine, cysteamine and WR 1065 in cell culture using V79-4 Chinese hamster lung cells. The three-day growth curve assays, useful to measure overall effects on cell growth, revealed lowest toxicity for alpha-methyl-homocysteine thiolactone (GL-2). Clonogenic survival tests, used to evaluate the retention of reproductive integrity, were carried out and revealed that GL-2 had no adverse effects in this test system. Radiation protection tests showed that GL-2 exhibited protective activity against radiation induced lethality above that seen with cysteine and cysteamine, but below WR 1065. However, GL-2 showed little or no negative effects toward the cell itself, in direct contrast to WR 1065. Our findings show a potentially important tool and principle to reduce toxicity of radiation protectors with analogous structures.
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Affiliation(s)
- K E Koch
- University of Utah, Dpt Medicinal Chemistry, Salt Lake City, UT, USA
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Koch KE, Wu Y, Xu J. Sugar and metabolic regulation of genes for sucrose metabolism: potential influence of maize sucrose synthase and soluble invertase responses on carbon partitioning and sugar sensing. J Exp Bot 1996; 47 Spec No:1179-1185. [PMID: 21245246 DOI: 10.1093/jxb/47.special_issue.1179] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Sugar responsiveness of genes for both paths of sucrose metabolism could provide a mechanism not only for transcriptional regulation of the first step in the use of imported carbon, but also for altering signals to the sugar-sensing system. This hypothesis was examined by comparison of (1) sugar regulation among maize genes for sucrose synthase and invertase, (2) their contrasting patterns of tissue expression, and (3) their influence on production of effectors for other sugar-responsive genes. Cloning and characterization of the Ivr1 and Ivr2 invertase genes of maize indicated that these genes belong to distinct subfamilies of the maize soluble invertase gene family. In addition, maize invertases can be grouped with the sucrose synthases (Sh1 and Sus1) on the basis of shared patterns of differential sugar-responsiveness and tissue-specific expression. Extension of this comparison to include genes for sucrose metabolism from other species revealed a more widespread association between starvation-tolerant expression and restricted patterns of tissue distribution. Consideration of current models for plant sugar-sensing systems and transport pathways suggested that the site and mechanism of sucrose cleavage in the cell could affect the magnitude and type of signal generated.
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Affiliation(s)
- K E Koch
- Plant Molecular and Cellular Biology Program, Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA
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Geiger DR, Koch KE, Shieh WJ. Effect of environmental factors on whole plant assimilate partitioning and associated gene expression. J Exp Bot 1996; 47 Spec No:1229-1238. [PMID: 21245254 DOI: 10.1093/jxb/47.special_issue.1229] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Partitioning of assimilated carbon among sink organs is a critical factor that controls the rate and pattern of plant growth. Time-course measurements of plant and organ growth rates are useful for determining how regulation of carbon partitioning controls plant growth. Measuring growth rates over a 24 h period reveals the current pattern of carbon partitioning that can be used to predict growth rates of specific sinks. Comparison of growth rates among sinks under defined conditions can point out key factors that regulate partitioning of recently assimilated carbon among sinks. Internal control of carbon partitioning by developmental programmes regulates the timing and site of carbon distribution among developing parts, thereby establishing the adaptive traits of a species, cultivar or transgenic construct. Regulation of partitioning in response to environmental factors establishes or restores allometric growth among plant parts and functional balance between the supply and use of carbon. Environmental stress often restricts resource availability while successful acclimation sets in motion processes that restore the supply. A key mechanism contributing to regulation of carbon partitioning is an expression of genes that control activity of the enzymes which initiate sucrose metabolism at specific sites and stages of ontogeny.
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Affiliation(s)
- D R Geiger
- Department of Biology, University of Dayton, Dayton, OH 45469-2320, USA
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Koch KE, Wu Y, Xu J. Sugar and metabolic regulation of genes for sucrose metabolism: potential influence of maize sucrose synthase and soluble invertase responses on carbon partitioning and sugar sensing. J Exp Bot 1996; 47 Spec No:1179-1185. [PMID: 21245246 DOI: 10.1093/jxb/47] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Sugar responsiveness of genes for both paths of sucrose metabolism could provide a mechanism not only for transcriptional regulation of the first step in the use of imported carbon, but also for altering signals to the sugar-sensing system. This hypothesis was examined by comparison of (1) sugar regulation among maize genes for sucrose synthase and invertase, (2) their contrasting patterns of tissue expression, and (3) their influence on production of effectors for other sugar-responsive genes. Cloning and characterization of the Ivr1 and Ivr2 invertase genes of maize indicated that these genes belong to distinct subfamilies of the maize soluble invertase gene family. In addition, maize invertases can be grouped with the sucrose synthases (Sh1 and Sus1) on the basis of shared patterns of differential sugar-responsiveness and tissue-specific expression. Extension of this comparison to include genes for sucrose metabolism from other species revealed a more widespread association between starvation-tolerant expression and restricted patterns of tissue distribution. Consideration of current models for plant sugar-sensing systems and transport pathways suggested that the site and mechanism of sucrose cleavage in the cell could affect the magnitude and type of signal generated.
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Affiliation(s)
- K E Koch
- Plant Molecular and Cellular Biology Program, Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA
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Roberts JC, Koch KE, Detrick SR, Warters RL, Lubec G. Thiazolidine prodrugs of cysteamine and cysteine as radioprotective agents. Radiat Res 1995; 143:203-13. [PMID: 7631013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The need for protection against the toxic effects of ionizing radiation comes from many different directions: occupational exposure, nuclear accidents, environmental sources and protection of normal tissue during the therapeutic irradiation of cancer. Sulfhydryl-containing compounds, including cysteamine and L-cysteine, have long been known to possess radioprotective properties, but their therapeutic utility is limited by their side effects at radioprotective doses. To avoid this drawback, thiazolidine prodrugs of cysteamine and L-cysteine were prepared by the condensation of each thioalmine with the aldose monosaccharides, D-ribose and D-glucose, producing RibCyst, GlcCyst, RibCys and GlcCys. The prodrugs were designed to liberate the parent thiolamine nonenzymatically, after ring opening and hydrolysis, which is then available to function as a radioprotective agent. Cysteamine's inherent toxicity, measured using Chinese hamster V79 cells growing in culture, was completely eliminated, even at concentrations as high as 25 mM, by providing the thiolamine in the form of a prodrug. Good protection against radiation-induced lethality was demonstrated by the cysteamine prodrugs using a clonogenic assay. Protection against radiation-induced DNA single-strand breaks, as measured by alkaline elution, was also shown by both RibCyst and GlcCyst; this activity was higher than that exhibited by either cysteamine or WR-1065. The L-cysteine prodrugs, RibCys and GlcCys, also possessed radioprotective abilities under most of the conditions studied. Protection against DNA damage was comparable between L-cysteine, WR-1065 and RibCys.
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Affiliation(s)
- J C Roberts
- Department of Medicinal Chemistry, University of Utah, Salt Lake City 84112, USA
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Affiliation(s)
- J Xu
- Plant Molecular and Cellular Biology Program, University of Florida, Gainesville 32611, USA
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Koch KE. Opportunities for pharmaceutical care with critical pathways. Top Hosp Pharm Manage 1995; 14:1-7. [PMID: 10140424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Critical pathways are multidisciplinary tools designed to improve patient care and efficiency. Almost every path requires some type of pharmacotherapeutic intervention, from selection of surgical prophylaxis to management of anticoagulation. Pharmacists should become involved with the critical pathway process because it offers an excellent opportunity to incorporate pharmaceutical care and to meet Joint Commission on Accreditation of Healthcare Organization compliance criteria.
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Affiliation(s)
- K E Koch
- North Mississippi Medical Center, Tupelo
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