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Kevei Z, Larriba E, Romero-Bosquet MD, Nicolás-Albujer M, Kurowski TJ, Mohareb F, Rickett D, Pérez-Pérez JM, Thompson AJ. Genes involved in auxin biosynthesis, transport and signalling underlie the extreme adventitious root phenotype of the tomato aer mutant. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2024; 137:76. [PMID: 38459215 PMCID: PMC10923741 DOI: 10.1007/s00122-024-04570-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 01/30/2024] [Indexed: 03/10/2024]
Abstract
The use of tomato rootstocks has helped to alleviate the soaring abiotic stresses provoked by the adverse effects of climate change. Lateral and adventitious roots can improve topsoil exploration and nutrient uptake, shoot biomass and resulting overall yield. It is essential to understand the genetic basis of root structure development and how lateral and adventitious roots are produced. Existing mutant lines with specific root phenotypes are an excellent resource to analyse and comprehend the molecular basis of root developmental traits. The tomato aerial roots (aer) mutant exhibits an extreme adventitious rooting phenotype on the primary stem. It is known that this phenotype is associated with restricted polar auxin transport from the juvenile to the more mature stem, but prior to this study, the genetic loci responsible for the aer phenotype were unknown. We used genomic approaches to define the polygenic nature of the aer phenotype and provide evidence that increased expression of specific auxin biosynthesis, transport and signalling genes in different loci causes the initiation of adventitious root primordia in tomato stems. Our results allow the selection of different levels of adventitious rooting using molecular markers, potentially contributing to rootstock breeding strategies in grafted vegetable crops, especially in tomato. In crops vegetatively propagated as cuttings, such as fruit trees and cane fruits, orthologous genes may be useful for the selection of cultivars more amenable to propagation.
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Affiliation(s)
- Zoltan Kevei
- Centre for Soil, AgriFood and Biosciences, Cranfield University, College Road, Bedfordshire, MK43 0AL, UK.
| | - Eduardo Larriba
- Instituto de Bioingeniería, Universidad Miguel Hernández, 03202, Elche, Spain
| | | | | | - Tomasz J Kurowski
- Centre for Soil, AgriFood and Biosciences, Cranfield University, College Road, Bedfordshire, MK43 0AL, UK
| | - Fady Mohareb
- Centre for Soil, AgriFood and Biosciences, Cranfield University, College Road, Bedfordshire, MK43 0AL, UK
| | - Daniel Rickett
- Syngenta Crop Protection, Jealott's Hill International Research Centre, Bracknell Berkshire, RG42 6EY, UK
| | | | - Andrew J Thompson
- Centre for Soil, AgriFood and Biosciences, Cranfield University, College Road, Bedfordshire, MK43 0AL, UK
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2
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Zhu J, Chen R, Feng Q, Huang C, Huang F, Du J, Wang J, Zhan X. Mechanistic insights into auxin-enhancing polycyclic aromatic hydrocarbon uptake by wheat roots: Evidence from in situ intracellular pH and root-surface H + flux. JOURNAL OF HAZARDOUS MATERIALS 2024; 465:133077. [PMID: 38035525 DOI: 10.1016/j.jhazmat.2023.133077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 10/17/2023] [Accepted: 11/22/2023] [Indexed: 12/02/2023]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are a group of extremely carcinogenic organic pollutants. Our previous findings have demonstrated that plant roots actively take up PAHs through co-transport with H+ ions. Auxin serves as a pivotal regulator of plant growth and development. However, it remains unclear whether the hormone can enhance the uptake of PAHs by plant roots. Hence, the wheat root exposed to PAHs with/without auxins was set to investigate how the auxin promotes the PAHs uptake by roots. In our study, auxin could significantly enhance the uptake of PAHs after 4 h of exposure. After the addition of auxin, the root tissue cytoplasmic pH value was decreased and the H+ influx was observed, indicating that the extracellular space was alkalinized in a short time. The increased H+ influx rate enhanced the uptake of PAHs. In addition, the H+-ATPase activity was also increased, suggesting that auxin activated two distinct and antagonistic H+ flux pathways, and the H+ influx pathway was dominant. Our findings offer important information for exploring the mechanism underlying auxin regulation of PAHs uptake and the phytoremediation of PAH-contaminated soil and water.
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Affiliation(s)
- Jiahui Zhu
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu Province 210095, People's Republic of China
| | - Ruonan Chen
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu Province 210095, People's Republic of China
| | - Qiurun Feng
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu Province 210095, People's Republic of China
| | - Chenghao Huang
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu Province 210095, People's Republic of China
| | - Fei Huang
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu Province 210095, People's Republic of China
| | - Jiani Du
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu Province 210095, People's Republic of China
| | - Jiawei Wang
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu Province 210095, People's Republic of China
| | - Xinhua Zhan
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu Province 210095, People's Republic of China.
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3
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Scarpella E. Axes and polarities in leaf vein formation. PLANT PHYSIOLOGY 2023; 193:112-124. [PMID: 37261944 DOI: 10.1093/plphys/kiad321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 04/21/2023] [Accepted: 05/04/2023] [Indexed: 06/03/2023]
Abstract
For multicellular organisms to develop, cells must grow, divide, and differentiate along preferential or exclusive orientations or directions. Moreover, those orientations, or axes, and directions, or polarities, must be coordinated between cells within and between tissues. Therefore, how axes and polarities are coordinated between cells is a key question in biology. In animals, such coordination mainly depends on cell migration and direct interaction between proteins protruding from the plasma membrane. Both cell movements and direct cell-cell interactions are prevented in plants by cell walls that surround plant cells and keep them apart and in place. Therefore, plants have evolved unique mechanisms to coordinate their cell axes and polarities. Here I will discuss evidence suggesting that understanding how leaf veins form may uncover those unique mechanisms. Indeed, unlike previously thought, the cell-to-cell polar transport of the plant hormone auxin along developing veins cannot account for many features of vein patterning. Instead, those features can be accounted for by models of vein patterning that combine polar auxin transport with auxin diffusion through plasmodesmata along the axis of developing veins. Though it remains unclear whether such a combination of polar transport and axial diffusion of auxin can account for the formation of the variety of vein patterns found in plant leaves, evidence suggests that such a combined mechanism may control plant developmental processes beyond vein patterning.
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Affiliation(s)
- Enrico Scarpella
- Department of Biological Sciences, University of Alberta, CW-405 Biological Sciences Building, Edmonton, AB T6G 2E9, Canada
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Liu Y, Liu Y, He Y, Yan Y, Yu X, Ali M, Pan C, Lu G. Cytokinin-inducible response regulator SlRR6 controls plant height through gibberellin and auxin pathways in tomato. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:4471-4488. [PMID: 37115725 DOI: 10.1093/jxb/erad159] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 04/27/2023] [Indexed: 06/19/2023]
Abstract
Plant height is a key agronomic trait regulated by several phytohormones such as gibberellins (GAs) and auxin. However, little is known about how cytokinin (CK) participates in this process. Here, we report that SlRR6, a type-A response regulator in the CK signaling pathway, positively regulates plant height in tomato. SlRR6 was induced by exogenous kinetin and GA3, but inhibited by indole-3-acetic acid (IAA). Knock out of SlRR6 reduced tomato plant height through shortening internode length, while overexpression of SlRR6 caused taller plants due to increased internode number. Cytological observation of longitudinal stems showed that both knock out and overexpression of SlRR6 generated larger cells, but significantly reduced cell numbers in each internode. Further studies demonstrated that overexpression of SlRR6 enhanced GA accumulation and lowered IAA content, along with expression changes in GA- and IAA-related genes. Exogenous paclobutrazol and IAA treatments restored the increased plant height phenotype in SlRR6-overexpressing lines. Yeast two-hybrid, bimolecular fluorescence complementation, and co-immunoprecipitation assays showed that SlRR6 interacts with a small auxin up RNA protein, SlSAUR58. Moreover, SlSAUR58-overexpressing plants were dwarf with decreased internode length. Overall, our findings establish SlRR6 as a vital component in the CK signaling, GA, and IAA regulatory network that controls plant height.
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Affiliation(s)
- Yue Liu
- Department of Horticulture, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Yichen Liu
- Department of Horticulture, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Yanjun He
- Institute of Vegetable Science, Zhejiang Academy of Agricultural Sciences, Hangzhou 310022, China
| | - Yanqiu Yan
- Department of Horticulture, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Xiaolin Yu
- Department of Horticulture, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Muhammad Ali
- Department of Horticulture, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Changtian Pan
- Department of Horticulture, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Gang Lu
- Department of Horticulture, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China
- Key Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Ministry of Agricultural, Zhejiang University, Hangzhou 310058, China
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Wei W, Tao JJ, Yin CC, Chen SY, Zhang JS, Zhang WK. Melatonin regulates gene expressions through activating auxin synthesis and signaling pathways. FRONTIERS IN PLANT SCIENCE 2022; 13:1057993. [PMID: 36582645 PMCID: PMC9792792 DOI: 10.3389/fpls.2022.1057993] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 11/11/2022] [Indexed: 06/17/2023]
Abstract
BACKGROUND Both melatonin and indole-3-acetic acid (IAA) are derived from tryptophan. And the most interesting and unsolved puzzle in melatonin research is that what is the relationship between melatonin and auxin? METHODS In this study, we performed transcriptome analysis with a time series method to disclose the connection of the two metabolites in soybean. RESULTS Our results reveal that melatonin and IAA treatments cause substantial overlaps in gene expression changes. Common genes of melatonin and IAA treatments could be sorted into clusters with very similar expression tendency. A KEGG assay showed that exogenous applied melatonin enriched differentially expressed genes in auxin biosynthesis and signaling pathways. For details, melatonin up-regulates several YUCCA genes which participate in auxin biosynthesis; melatonin also enhances expression levels of auxin receptor coding genes, such as TIR1, AFB3 and AFB5; dozens of genes involved in auxin transport, such as AUXI and PIN, are regulated by melatonin similarly as by auxin; auxin-responsive genes, such as IAA, ARF, GH3 and SAUR-like genes, intensively respond to melatonin as well as to auxin. A DR5 promoter mediated GUS staining assay showed that low concentration of melatonin could induce auxin biosynthesis in a dosage manner, whereas high concentration of melatonin would eliminate such effect. At last, gene ontology (GO) analysis suggests that melatonin treatment has similar characteristics as auxin treatment in many processes. However, the two molecules still keep their own features respectively. For example, melatonin takes part in stress responses, while IAA treatment enriches the GO terms that related to cell growth. CONCLUSION Taken together, exogenous applied melatonin, if not exceeds the appropriate concentration, could promote auxin responses range from biosynthesis to signaling transduction. Thus, our research is a key part to explain the auxin-like roles of melatonin in regulating plant growth.
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Affiliation(s)
- Wei Wei
- State Key Lab of Plant Genomics, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, China
| | - Jian-Jun Tao
- State Key Lab of Plant Genomics, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, China
| | - Cui-Cui Yin
- State Key Lab of Plant Genomics, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, China
| | - Shou-Yi Chen
- State Key Lab of Plant Genomics, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, China
| | - Jin-Song Zhang
- State Key Lab of Plant Genomics, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, China
- College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Wan-Ke Zhang
- State Key Lab of Plant Genomics, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, China
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6
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Band LR. Auxin fluxes through plasmodesmata. THE NEW PHYTOLOGIST 2021; 231:1686-1692. [PMID: 34053083 DOI: 10.1111/nph.17517] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 04/29/2021] [Indexed: 05/27/2023]
Abstract
Characterising the processes that control auxin dynamics is essential to understanding how auxin regulates plant development. Over recent years, several studies have investigated auxin diffusion through plasmodesmata, characterising this cell-to-cell diffusion and demonstrating that it affects auxin distributions. Furthermore, studies have shown that plasmodesmatal auxin diffusion affects developmental processes, including phototropism, lateral root emergence and leaf hyponasty. This short Tansley Insight review describes how these studies have contributed to our understanding of auxin dynamics and discusses potential future directions in this area.
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Affiliation(s)
- Leah R Band
- Centre for Mathematical Medicine and Biology, School of Mathematical Sciences, University of Nottingham, Nottingham, NG7 2RD, UK
- Division of Plant and Crop Sciences, School of Biosciences, University of Nottingham, Sutton Bonington, LE12 5RD, UK
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Differential biosynthesis and cellular permeability explain longitudinal gibberellin gradients in growing roots. Proc Natl Acad Sci U S A 2021; 118:1921960118. [PMID: 33602804 PMCID: PMC7923382 DOI: 10.1073/pnas.1921960118] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Growth hormones are mobile chemicals that exert considerable influence over how multicellular organisms like animals and plants take on their shape and form. Of particular interest is the distribution of such hormones across cells and tissues. In plants, one of these hormones, gibberellin (GA), is known to regulate cell multiplication and cell expansion to increase the rate at which roots grow. In this work, biosensor measurements were combined with theoretical models to elucidate the biochemical mechanisms that direct GA distribution and how these patterns relate to root growth. Our detailed understanding of how GA distributions are controlled in roots should prove a valuable model for understanding the makings of the many other hormone distributions that influence how plants grow. Control over cell growth by mobile regulators underlies much of eukaryotic morphogenesis. In plant roots, cell division and elongation are separated into distinct longitudinal zones and both division and elongation are influenced by the growth regulatory hormone gibberellin (GA). Previously, a multicellular mathematical model predicted a GA maximum at the border of the meristematic and elongation zones. However, GA in roots was recently measured using a genetically encoded fluorescent biosensor, nlsGPS1, and found to be low in the meristematic zone grading to a maximum at the end of the elongation zone. Furthermore, the accumulation rate of exogenous GA was also found to be higher in the elongation zone. It was still unknown which biochemical activities were responsible for these mobile small molecule gradients and whether the spatiotemporal correlation between GA levels and cell length is important for root cell division and elongation patterns. Using a mathematical modeling approach in combination with high-resolution GA measurements in vivo, we now show how differentials in several biosynthetic enzyme steps contribute to the endogenous GA gradient and how differential cellular permeability contributes to an accumulation gradient of exogenous GA. We also analyzed the effects of altered GA distribution in roots and did not find significant phenotypes resulting from increased GA levels or signaling. We did find a substantial temporal delay between complementation of GA distribution and cell division and elongation phenotypes in a GA deficient mutant. Together, our results provide models of how GA gradients are directed and in turn direct root growth.
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Ravichandran SJ, Linh NM, Scarpella E. The canalization hypothesis - challenges and alternatives. THE NEW PHYTOLOGIST 2020; 227:1051-1059. [PMID: 32285457 DOI: 10.1111/nph.16605] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Accepted: 04/01/2020] [Indexed: 05/14/2023]
Abstract
The 'canalization hypothesis' was suggested 50 years ago by Tsvi Sachs to account for the formation of vascular strands in response to wounding or auxin application. The hypothesis proposes that positive feedback between auxin movement through a cell and the cell's auxin conductivity leads to the gradual selection of narrow 'canals' of polar auxin transport that will differentiate into vascular strands. Though the hypothesis has provided an invaluable conceptual framework to understand the patterned formation of vascular strands, evidence has been accumulating that seems to be incompatible with the hypothesis. We suggest that the challenging evidence is incompatible with current interpretations of the hypothesis but not with the concept at the core of the hypothesis' original formulation.
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Affiliation(s)
- Sree Janani Ravichandran
- Department of Biological Sciences, University of Alberta, CW-405 Biological Sciences Building, Edmonton, AB, T6G 2E9, Canada
| | - Nguyen Manh Linh
- Department of Biological Sciences, University of Alberta, CW-405 Biological Sciences Building, Edmonton, AB, T6G 2E9, Canada
| | - Enrico Scarpella
- Department of Biological Sciences, University of Alberta, CW-405 Biological Sciences Building, Edmonton, AB, T6G 2E9, Canada
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9
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Wheeldon CD, Bennett T. There and back again: An evolutionary perspective on long-distance coordination of plant growth and development. Semin Cell Dev Biol 2020; 109:55-67. [PMID: 32576500 DOI: 10.1016/j.semcdb.2020.06.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 06/09/2020] [Accepted: 06/16/2020] [Indexed: 12/17/2022]
Abstract
Vascular plants, unlike bryophytes, have a strong root-shoot dichotomy in which the tissue systems are mutually interdependent; roots are completely dependent on shoots for photosynthetic sugars, and shoots are completely dependent on roots for water and mineral nutrients. Long-distance communication between shoot and root is therefore critical for the growth, development and survival of vascular plants, especially with regard to variable environmental conditions. However, this long-distance signalling does not appear an ancestral feature of land plants, and has likely arisen in vascular plants to service the radical alterations in body-plan seen in this taxon. In this review, we examine the defined hormonal root-to-shoot and shoot-to-root signalling pathways that coordinate the growth of vascular plants, with a particular view to understanding how these pathways may have evolved. We highlight the completely divergent roles of isopentenyl-adenine and trans-zeatin cytokinin species in long-distance signalling, and ask whether cytokinin can really be considered as a single class of hormones in the light of recent research. We also discuss the puzzlingly sparse evidence for auxin as a shoot-to-root signal, the evolutionary re-purposing of strigolactones and gibberellins as hormonal signals, and speculate on the possible role of sugars as long-distance signals. We conclude by discussing the 'design principles' of long-distance signalling in vascular plants.
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Affiliation(s)
- Cara D Wheeldon
- School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Tom Bennett
- School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK.
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10
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Deletion in the Promoter of PcPIN-L Affects the Polar Auxin Transport in Dwarf Pear (Pyrus communis L.). Sci Rep 2019; 9:18645. [PMID: 31819123 PMCID: PMC6901534 DOI: 10.1038/s41598-019-55195-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Accepted: 11/25/2019] [Indexed: 12/31/2022] Open
Abstract
Dwarf cultivars or dwarfing rootstocks enable high-density planting and are therefore highly desirable in modern pear production. Previously, we found that the dwarf growth habit of pear is controlled by a single dominant gene PcDw. In this study, PcPIN-L (PCP021016) was cloned from dwarf-type and standard-type pears. PcPIN-L expression was significantly lower in the dwarf-type pears than in standard-type pears, which was caused by the CT repeat deletion in the promoter of dwarf-type pears. PcPIN-L overexpression in tobacco plants enhanced the growth of the stems and the roots. Notably, the indole acetic acid (IAA) content decreased in the shoot tips and increased in the stems of transgenic lines compared with wild type, which is consistent with the greater IAA content in the shoot tips and lower IAA content in the stems of dwarf-type pears than in standard-type pears. The CT repeat deletion in the promoter that causes a decrease in promoter activity is associated with lower PcPIN-L expression in the dwarf-type pears, which might limit the polar auxin transport and in turn result in the dwarf phenotype. Taken together, the results provide a novel dwarfing molecular mechanism in perennial woody plants.
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11
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Haskovec J, Jönsson H, Kreusser LM, Markowich P. Auxin transport model for leaf venation. Proc Math Phys Eng Sci 2019; 475:20190015. [PMID: 31824212 PMCID: PMC6894547 DOI: 10.1098/rspa.2019.0015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2019] [Accepted: 10/22/2019] [Indexed: 11/12/2022] Open
Abstract
The plant hormone auxin controls many aspects of the development of plants. One striking dynamical feature is the self-organization of leaf venation patterns which is driven by high levels of auxin within vein cells. The auxin transport is mediated by specialized membrane-localized proteins. Many venation models have been based on polarly localized efflux-mediator proteins of the PIN family. Here, we investigate a modelling framework for auxin transport with a positive feedback between auxin fluxes and transport capacities that are not necessarily polar, i.e. directional across a cell wall. Our approach is derived from a discrete graph-based model for biological transportation networks, where cells are represented by graph nodes and intercellular membranes by edges. The edges are not a priori oriented and the direction of auxin flow is determined by its concentration gradient along the edge. We prove global existence of solutions to the model and the validity of Murray's Law for its steady states. Moreover, we demonstrate with numerical simulations that the model is able connect an auxin source-sink pair with a mid-vein and that it can also produce branching vein patterns. A significant innovative aspect of our approach is that it allows the passage to a formal macroscopic limit which can be extended to include network growth. We perform mathematical analysis of the macroscopic formulation, showing the global existence of weak solutions for an appropriate parameter range.
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Affiliation(s)
- Jan Haskovec
- Mathematics, CEMSE, KAUST, Thuwal 23955-6900, KSA
| | - Henrik Jönsson
- Sainsbury Laboratory, University of Cambridge, Bateman Street, Cambridge CB2 1LR, UK
- DAMTP, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, UK
| | | | - Peter Markowich
- Mathematics, CEMSE, KAUST, Thuwal 23955-6900, KSA
- Faculty of Mathematics, University of Vienna, Oskar-Morgenstern-Platz 1, Vienna 1090, Austria
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12
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Molecular Responses during Plant Grafting and Its Regulation by Auxins, Cytokinins, and Gibberellins. Biomolecules 2019; 9:biom9090397. [PMID: 31443419 PMCID: PMC6770456 DOI: 10.3390/biom9090397] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Revised: 08/20/2019] [Accepted: 08/21/2019] [Indexed: 12/25/2022] Open
Abstract
Plant grafting is an important horticulture technique used to produce a new plant after joining rootstock and scion. This is one of the most used techniques by horticulturists to enhance the quality and production of various crops. Grafting helps in improving the health of plants, their yield, and the quality of plant products, along with the enhancement of their postharvest life. The main process responsible for successful production of grafted plants is the connection of vascular tissues. This step determines the success rate of grafts and hence needs to be studied in detail. There are many factors that regulate the connection of scion and stock, and plant hormones are of special interest for researchers in the recent times. These phytohormones act as signaling molecules and have the capability of translocation across the graft union. Plant hormones, mainly auxins, cytokinins, and gibberellins, play a major role in the regulation of various key physiological processes occurring at the grafting site. In the current review, we discuss the molecular mechanisms of graft development and the phytohormone-mediated regulation of the growth and development of graft union.
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13
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Li XR, Vroomans RMA, Fox S, Grieneisen VA, Østergaard L, Marée AFM. Systems Biology Approach Pinpoints Minimum Requirements for Auxin Distribution during Fruit Opening. MOLECULAR PLANT 2019; 12:863-878. [PMID: 31128274 PMCID: PMC6557309 DOI: 10.1016/j.molp.2019.05.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 05/01/2019] [Accepted: 05/03/2019] [Indexed: 06/09/2023]
Abstract
The phytohormone auxin is implied in steering various developmental decisions during plant morphogenesis in a concentration-dependent manner. Auxin maxima have been shown to maintain meristematic activity, for example, of the root apical meristem, and position new sites of outgrowth, such as during lateral root initiation and phyllotaxis. More recently, it has been demonstrated that sites of auxin minima also provide positional information. In the developing Arabidopsis fruit, auxin minima are required for correct differentiation of the valve margin. It remains unclear, however, how this auxin minimum is generated and maintained. Here, we employ a systems biology approach to model auxin transport based on experimental observations. This allows us to determine the minimal requirements for its establishment. Our simulations reveal that two alternative processes-which we coin "flux-barrier" and "flux-passage"-are both able to generate an auxin minimum, but under different parameter settings. Both models are in principle able to yield similar auxin profiles but present qualitatively distinct patterns of auxin flux. The models were tested by tissue-specific inducible ablation, revealing that the auxin minimum in the fruit is most likely generated by a flux-passage process. Model predictions were further supported through 3D PIN localization imaging and implementing experimentally observed transporter localization. Through such an experimental-modeling cycle, we predict how the auxin minimum gradually matures during fruit development to ensure timely fruit opening and seed dispersal.
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Affiliation(s)
- Xin-Ran Li
- Crop Genetics, John Innes Centre, Norwich NR4 7UH, UK
| | - Renske M A Vroomans
- Computational and Systems Biology, John Innes Centre, Norwich NR4 7UH, UK; Centre of Excellence in Computational and Experimental Developmental Biology, Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
| | - Samantha Fox
- Cell and Developmental Biology, John Innes Centre, Norwich NR4 7UH, UK
| | - Verônica A Grieneisen
- Computational and Systems Biology, John Innes Centre, Norwich NR4 7UH, UK; School of Biosciences, Cardiff University, Cardiff CF10 3AX, Wales, UK
| | | | - Athanasius F M Marée
- Computational and Systems Biology, John Innes Centre, Norwich NR4 7UH, UK; School of Biosciences, Cardiff University, Cardiff CF10 3AX, Wales, UK.
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14
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Huang LK, Liao YY, Lin WH, Lin SM, Liu TY, Lee CH, Pan RL. Potassium Stimulation of IAA Transport Mediated by the Arabidopsis Importer AUX1 Investigated in a Heterologous Yeast System. J Membr Biol 2019; 252:183-194. [PMID: 31053903 DOI: 10.1007/s00232-019-00065-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2018] [Accepted: 04/15/2019] [Indexed: 10/26/2022]
Abstract
Auxin regulates diverse processes involved in plant growth and development. AUX1 is the first identified and most widely investigated auxin importer, and plays an important role in root gravitropism and the development of lateral root and root hair. However, the regulation of auxin transport by AUX1 is still not well understood. In this study, we examined the effect of metal ions on AUX1 transport function and found that the activity could be specifically stimulated four times by K+. Further experiments revealed the preference of KF on the enhancement of transport activity of AUX1 over KCl, KBr, and KI. In addition, the interaction between K+ and AUX1 confers AUX1 more resistant to thermal stress but more vulnerable to proteolysis. Conventional chemical modification indicated that the extracellular acidic amino acids of AUX1 play a key role in the K+ stimulation. Site-specific mutagenesis showed that the replacement of Asp166, Asp293, and Asp312 of AUX1 to alanine deteriorated the K+-stimulated auxin transport. By contrast, when these residues were mutated to glutamate, lysine, or asparagine, only the D312E variant restored the IAA transport activity to the wild-type level. It is thus convinced that D312 is presumably the most promising residue for the K+ stimulation on AUX1.
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Affiliation(s)
- Li-Kun Huang
- Department of Life Science and Institute of Bioinformatics and Structural Biology, College of Life Science, National Tsing Hua University, No. 101, Sec. 2, Guangfu Rd. East Dist., Hsin Chu, 30013, Taiwan, Republic of China
| | - Ya-Yun Liao
- Department of Life Science and Institute of Bioinformatics and Structural Biology, College of Life Science, National Tsing Hua University, No. 101, Sec. 2, Guangfu Rd. East Dist., Hsin Chu, 30013, Taiwan, Republic of China
| | - Wei-Hua Lin
- Department of Life Science and Institute of Bioinformatics and Structural Biology, College of Life Science, National Tsing Hua University, No. 101, Sec. 2, Guangfu Rd. East Dist., Hsin Chu, 30013, Taiwan, Republic of China
| | - Shih-Ming Lin
- Department of Biotechnology and Bioindustry Sciences, National Cheng Kung University, Tainan, 701, Taiwan, Republic of China
| | - Tzu-Yin Liu
- Department of Life Science and Institute of Bioinformatics and Structural Biology, College of Life Science, National Tsing Hua University, No. 101, Sec. 2, Guangfu Rd. East Dist., Hsin Chu, 30013, Taiwan, Republic of China
| | - Ching-Hung Lee
- Department of Life Science and Institute of Bioinformatics and Structural Biology, College of Life Science, National Tsing Hua University, No. 101, Sec. 2, Guangfu Rd. East Dist., Hsin Chu, 30013, Taiwan, Republic of China.
| | - Rong-Long Pan
- Department of Life Science and Institute of Bioinformatics and Structural Biology, College of Life Science, National Tsing Hua University, No. 101, Sec. 2, Guangfu Rd. East Dist., Hsin Chu, 30013, Taiwan, Republic of China.
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16
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Abstract
Asymmetric auxin distribution is instrumental for the differential growth that causes organ bending on tropic stimuli and curvatures during plant development. Local differences in auxin concentrations are achieved mainly by polarized cellular distribution of PIN auxin transporters, but whether other mechanisms involving auxin homeostasis are also relevant for the formation of auxin gradients is not clear. Here we show that auxin methylation is required for asymmetric auxin distribution across the hypocotyl, particularly during its response to gravity. We found that loss-of-function mutants in Arabidopsis IAA CARBOXYL METHYLTRANSFERASE1 (IAMT1) prematurely unfold the apical hook, and that their hypocotyls are impaired in gravitropic reorientation. This defect is linked to an auxin-dependent increase in PIN gene expression, leading to an increased polar auxin transport and lack of asymmetric distribution of PIN3 in the iamt1 mutant. Gravitropic reorientation in the iamt1 mutant could be restored with either endodermis-specific expression of IAMT1 or partial inhibition of polar auxin transport, which also results in normal PIN gene expression levels. We propose that IAA methylation is necessary in gravity-sensing cells to restrict polar auxin transport within the range of auxin levels that allow for differential responses.
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Zhang M, Lu X, Li C, Zhang B, Zhang C, Zhang XS, Ding Z. Auxin Efflux Carrier ZmPGP1 Mediates Root Growth Inhibition under Aluminum Stress. PLANT PHYSIOLOGY 2018; 177:819-832. [PMID: 29720555 PMCID: PMC6001327 DOI: 10.1104/pp.17.01379] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 04/15/2018] [Indexed: 05/25/2023]
Abstract
Auxin has been shown to enhance root growth inhibition under aluminum (Al) stress in Arabidopsis (Arabidopsis thaliana). However, in maize (Zea mays), auxin may play a negative role in the Al-induced inhibition of root growth. In this study, we identified mutants deficient in the maize auxin efflux carrier P-glycoprotein (ZmPGP1) after ethyl methanesulfonate mutagenesis and used them to elucidate the contribution of ZmPGP1 to Al-induced root growth inhibition. Root growth in the zmpgp1 mutant, which forms shortened roots and is hyposensitive to auxin, was less inhibited by Al stress than that in the inbred line B73. In the zmpgp1 mutants, the root tips displayed higher auxin accumulation and enhanced auxin signaling under Al stress, which was also consistent with the increased expression of auxin-responsive genes. Based on the behavior of the auxin-responsive marker transgene, DR5rev:RFP, we concluded that Al stress reduced the level of auxin in the root tip, which contrasts with the tendency of Al stress-induced Arabidopsis plants to accumulate more auxin in their root tips. In addition, Al stress induced the expression of ZmPGP1 Therefore, in maize, Al stress is associated with reduced auxin accumulation in root tips, a process that is regulated by ZmPGP1 and thus causes inhibition of root growth. This study provides further evidence about the role of auxin and auxin polar transport in Al-induced root growth regulation in maize.
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Affiliation(s)
- Maolin Zhang
- The Key Laboratory of Plant Cell Engineering and Germplasm Innovation, College of Life Sciences, Shandong University, Jinan 250100, Shandong, China
| | - Xiaoduo Lu
- Insititue of Molecular Breeding for Maize, Qilu Normal University, Jinan 250200, China
| | - Cuiling Li
- The Key Laboratory of Plant Cell Engineering and Germplasm Innovation, College of Life Sciences, Shandong University, Jinan 250100, Shandong, China
| | - Bing Zhang
- The Key Laboratory of Plant Cell Engineering and Germplasm Innovation, College of Life Sciences, Shandong University, Jinan 250100, Shandong, China
| | - Chunyi Zhang
- Department of Crop Genomics and Genetic Improvement, Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Xian-Sheng Zhang
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian 271018, Shandong, China
| | - Zhaojun Ding
- The Key Laboratory of Plant Cell Engineering and Germplasm Innovation, College of Life Sciences, Shandong University, Jinan 250100, Shandong, China
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18
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Sun H, Feng F, Liu J, Zhao Q. Nitric Oxide Affects Rice Root Growth by Regulating Auxin Transport Under Nitrate Supply. FRONTIERS IN PLANT SCIENCE 2018; 9:659. [PMID: 29875779 PMCID: PMC5974057 DOI: 10.3389/fpls.2018.00659] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 04/30/2018] [Indexed: 05/08/2023]
Abstract
Nitrogen (N) is a major essential nutrient for plant growth, and rice is an important food crop globally. Although ammonium (NH4+) is the main N source for rice, nitrate (NO3-) is also absorbed and utilized. Rice responds to NO3- supply by changing root morphology. However, the mechanisms of rice root growth and formation under NO3- supply are unclear. Nitric oxide (NO) and auxin are important regulators of root growth and development under NO3- supply. How the interactions between NO and auxin in regulating root growth in response to NO3- are unknown. In this study, the levels of indole-3-acetic acid (IAA) and NO in roots, and the responses of lateral roots (LRs) and seminal roots (SRs) to NH4+ and NO3-, were investigated using wild-type (WT) rice, as well as osnia2 and ospin1b mutants. NO3- supply promoted LR formation and SR elongation. The effects of NO donor and NO inhibitor/scavenger supply on NO levels and the root morphology of WT and nia2 mutants under NH4+ or NO3- suggest that NO3--induced NO is generated by the nitrate reductase (NR) pathway rather than the NO synthase (NOS)-like pathway. IAA levels, [3H] IAA transport, and PIN gene expression in roots were enhanced under NO3- relative to NH4+ supply. These results suggest that NO3- regulates auxin transport in roots. Application of SNP under NH4+ supply, or of cPTIO under NO3- supply, resulted in auxin levels in roots similar to those under NO3- and NH4+ supply, respectively. Compared to WT, the roots of the ospin1b mutant had lower auxin levels, fewer LRs, and shorter SRs. Thus, NO affects root growth by regulating auxin transport in response to NO3-. Overall, our findings suggest that NO3- influences LR formation and SR elongation by regulating auxin transport via a mechanism involving NO.
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Affiliation(s)
- Huwei Sun
- *Correspondence: Huwei Sun, Quanzhi Zhao,
| | | | | | - Quanzhi Zhao
- Laboratory of Rice Biology in Henan Province, Collaborative Innovation Center of Henan Grain Crops, College of Agronomy, Henan Agricultural University, Zhengzhou, China
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AUX1-mediated root hair auxin influx governs SCF TIR1/AFB-type Ca 2+ signaling. Nat Commun 2018; 9:1174. [PMID: 29563504 PMCID: PMC5862985 DOI: 10.1038/s41467-018-03582-5] [Citation(s) in RCA: 120] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 02/26/2018] [Indexed: 01/01/2023] Open
Abstract
Auxin is a key regulator of plant growth and development, but the causal relationship between hormone transport and root responses remains unresolved. Here we describe auxin uptake, together with early steps in signaling, in Arabidopsis root hairs. Using intracellular microelectrodes we show membrane depolarization, in response to IAA in a concentration- and pH-dependent manner. This depolarization is strongly impaired in aux1 mutants, indicating that AUX1 is the major transporter for auxin uptake in root hairs. Local intracellular auxin application triggers Ca2+ signals that propagate as long-distance waves between root cells and modulate their auxin responses. AUX1-mediated IAA transport, as well as IAA- triggered calcium signals, are blocked by treatment with the SCFTIR1/AFB - inhibitor auxinole. Further, they are strongly reduced in the tir1afb2afb3 and the cngc14 mutant. Our study reveals that the AUX1 transporter, the SCFTIR1/AFB receptor and the CNGC14 Ca2+ channel, mediate fast auxin signaling in roots. Auxin regulates multiple aspects of plant growth and development. Here Dindas et al. show that in root-hair cells, the AUX1 auxin influx carrier mediates proton-driven auxin import that is perceived by auxin receptors and coupled to Ca2+ waves that may modulate adaptive responses in the root.
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Saravana Kumar RM, Gao LX, Yuan HW, Xu DB, Liang Z, Tao SC, Guo WB, Yan DL, Zheng BS, Edqvist J. Auxin enhances grafting success in Carya cathayensis (Chinese hickory). PLANTA 2018; 247:761-772. [PMID: 29214445 PMCID: PMC5809526 DOI: 10.1007/s00425-017-2824-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Accepted: 11/28/2017] [Indexed: 05/12/2023]
Abstract
MAIN CONCLUSION Application of auxin to root stock and scion increases the success rate of grafting in Chinese hickory. The nuts of the Chinese hickory (Carya cathayensis) tree are considered both delicious and healthy. The popularity and high demand result is that the hickory nuts are of very high economical value for horticulture. This is particularly true for the Zhejiang province in eastern China where this tree is widely cultivated. However, there are several difficulties surrounding the hickory cultivation, such as for example long vegetative growth, tall trees, labour-intensive nut picking, and slow variety improvements. These complications form a great bottleneck in the expansion of the hickory industry. The development of an efficient grafting procedure could surpass at least some of these problems. In this study, we demonstrate that application of the auxin indole-3-acetic acid promotes the grafting process in hickory, whereas application of the auxin transport inhibitor 1-N-naphthylphthalamic acid inhibits the grafting process. Furthermore, we have identified hickory genes in the PIN, ABCB, and AUX/LAX-families known to encode influx and efflux carriers in the polar transport of auxin. We show that increased expression of several of these genes, such as CcPIN1b and CcLAX3, is correlating with successful grafting.
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Affiliation(s)
- R M Saravana Kumar
- State Key Laboratory for Subtropical Silviculture, Zhejiang A and F University, Linan, 311300, Zhejiang, China
| | - Liu Xiao Gao
- Laboratory of Fruit Quality Biology, Zhejiang Provincial Key Laboratory of Horticultural Plant Integrative Biology, Zhejiang University, Zinjingang campus, Hangzhou, 310058, China
| | - Hu Wei Yuan
- State Key Laboratory for Subtropical Silviculture, Zhejiang A and F University, Linan, 311300, Zhejiang, China
| | - Dong Bin Xu
- State Key Laboratory for Subtropical Silviculture, Zhejiang A and F University, Linan, 311300, Zhejiang, China
| | - Zhao Liang
- State Key Laboratory for Subtropical Silviculture, Zhejiang A and F University, Linan, 311300, Zhejiang, China
| | - Shen Chen Tao
- State Key Laboratory for Subtropical Silviculture, Zhejiang A and F University, Linan, 311300, Zhejiang, China
| | - Wen Bin Guo
- State Key Laboratory for Subtropical Silviculture, Zhejiang A and F University, Linan, 311300, Zhejiang, China
| | - Dao Liang Yan
- State Key Laboratory for Subtropical Silviculture, Zhejiang A and F University, Linan, 311300, Zhejiang, China
| | - Bing Song Zheng
- State Key Laboratory for Subtropical Silviculture, Zhejiang A and F University, Linan, 311300, Zhejiang, China
| | - Johan Edqvist
- IFM, Linköping University, 581 83, Linköping, Sweden.
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21
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Gan Z, Wang Y, Wu T, Xu X, Zhang X, Han Z. MdPIN1b encodes a putative auxin efflux carrier and has different expression patterns in BC and M9 apple rootstocks. PLANT MOLECULAR BIOLOGY 2018; 96:353-365. [PMID: 29340953 DOI: 10.1007/s11103-018-0700-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 01/08/2018] [Indexed: 06/07/2023]
Abstract
Lower promoter activity is closely associated with lower MdPIN1b expression in the M9 interstem, which might contribute to the dwarfing effect in apple trees. Apple trees grafted onto dwarfing rootstock Malling 9 (M9) produce dwarfing tree architecture with high yield and widely applying in production. Previously, we have reported that in Malus 'Red Fuji' (RF) trees growing on M9 interstem and Baleng Crab (BC) rootstock, IAA content was relatively higher in bark tissue of M9 interstem than that in scion or rootstock. As IAA polar transportation largely depends on the PIN-FORMED (PIN) auxin efflux carrier. Herein, we identify two putative auxin efflux carrier genes in Malus genus, MdPIN1a and MdPIN1b, which were closely related to the AtPIN1. We found that MdPIN1b was expressed preferentially in BC and M9, and the expression of MdPIN1b was significantly lower in the phloem of M9 interstem than that in the scion and rootstock. The distinct expression of MdPIN1b and IAA content were concentrated in the cambium and adjacent xylem or phloem, and MdPIN1b protein was localized on cell plasma membrane in onion epidermal cells transiently expressing 35S:MdPIN1b-GFP fusion protein. Interestingly, an MdPIN1b mutant allele in the promoter region upstream of M9 exhibited decreased MdPIN1b expression compared to BC. MdPIN1b over-expressing interstem in tobacco exhibited increased polar auxin transport. It is proposed that natural allelic differences decreased promoter activity is closely associated with lower MdPIN1b expression in the M9 interstem, which might limit the basipetal transport of auxin, and in turn might contribute to the dwarfing effect. Taken together, these results reveal allelic variation underlying an important apple rootstock trait, and specifically a novel molecular genetic mechanism underlying dwarfing mechanism.
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Affiliation(s)
- Zengyu Gan
- Institute of Horticultural Plants, College of Horticulture, China Agricultural University, Beijing, 100193, People's Republic of China
- Key Laboratory of Stress Physiology and Molecular Biology for Fruit Trees in Beijing Municipality, China Agricultural University, Beijing, 100193, People's Republic of China
- Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Nutrition and Physiology) in Ministry of Agriculture, China Agricultural University, Beijing, 100193, People's Republic of China
| | - Yi Wang
- Institute of Horticultural Plants, College of Horticulture, China Agricultural University, Beijing, 100193, People's Republic of China
- Key Laboratory of Stress Physiology and Molecular Biology for Fruit Trees in Beijing Municipality, China Agricultural University, Beijing, 100193, People's Republic of China
- Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Nutrition and Physiology) in Ministry of Agriculture, China Agricultural University, Beijing, 100193, People's Republic of China
| | - Ting Wu
- Institute of Horticultural Plants, College of Horticulture, China Agricultural University, Beijing, 100193, People's Republic of China
- Key Laboratory of Stress Physiology and Molecular Biology for Fruit Trees in Beijing Municipality, China Agricultural University, Beijing, 100193, People's Republic of China
- Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Nutrition and Physiology) in Ministry of Agriculture, China Agricultural University, Beijing, 100193, People's Republic of China
| | - Xuefeng Xu
- Institute of Horticultural Plants, College of Horticulture, China Agricultural University, Beijing, 100193, People's Republic of China
- Key Laboratory of Stress Physiology and Molecular Biology for Fruit Trees in Beijing Municipality, China Agricultural University, Beijing, 100193, People's Republic of China
- Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Nutrition and Physiology) in Ministry of Agriculture, China Agricultural University, Beijing, 100193, People's Republic of China
| | - Xinzhong Zhang
- Institute of Horticultural Plants, College of Horticulture, China Agricultural University, Beijing, 100193, People's Republic of China
- Key Laboratory of Stress Physiology and Molecular Biology for Fruit Trees in Beijing Municipality, China Agricultural University, Beijing, 100193, People's Republic of China
- Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Nutrition and Physiology) in Ministry of Agriculture, China Agricultural University, Beijing, 100193, People's Republic of China
| | - Zhenhai Han
- Institute of Horticultural Plants, College of Horticulture, China Agricultural University, Beijing, 100193, People's Republic of China.
- Key Laboratory of Stress Physiology and Molecular Biology for Fruit Trees in Beijing Municipality, China Agricultural University, Beijing, 100193, People's Republic of China.
- Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Nutrition and Physiology) in Ministry of Agriculture, China Agricultural University, Beijing, 100193, People's Republic of China.
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Linh NM, Verna C, Scarpella E. Coordination of cell polarity and the patterning of leaf vein networks. CURRENT OPINION IN PLANT BIOLOGY 2018; 41:116-124. [PMID: 29278780 DOI: 10.1016/j.pbi.2017.09.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2017] [Revised: 09/12/2017] [Accepted: 09/15/2017] [Indexed: 06/07/2023]
Abstract
During development, the behavior of cells in tissues is coordinated along specific orientations or directions by coordinating the polar localization of components in those cells. The coordination of such cell polarity is perhaps nowhere more spectacular than in developing leaves, where the polarity of hundreds of cells is coordinated in the leaf epidermis and inner tissue to pattern vein networks. Available evidence suggests that the spectacular coordination of cell polarity that patterns vein networks is controlled by auxin transport and levels, and by genes that have been implicated in the polar localization of auxin transporters.
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Affiliation(s)
- Nguyen Manh Linh
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Carla Verna
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Enrico Scarpella
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada.
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23
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Liu J, Moore S, Chen C, Lindsey K. Crosstalk Complexities between Auxin, Cytokinin, and Ethylene in Arabidopsis Root Development: From Experiments to Systems Modeling, and Back Again. MOLECULAR PLANT 2017; 10:1480-1496. [PMID: 29162416 DOI: 10.1016/j.molp.2017.11.002] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2017] [Revised: 11/06/2017] [Accepted: 11/07/2017] [Indexed: 05/23/2023]
Abstract
Understanding how hormones and genes interact to coordinate plant growth in a changing environment is a major challenge in plant developmental biology. Auxin, cytokinin, and ethylene are three important hormones that regulate many aspects of plant development. This review critically evaluates the crosstalk between the three hormones in Arabidopsis root development. We integrate a variety of experimental data into a crosstalk network, which reveals multiple layers of complexity in auxin, cytokinin, and ethylene crosstalk. In particular, data integration reveals an additional, largely overlooked link between the ethylene and cytokinin pathways, which acts through a phosphorelay mechanism. This proposed link addresses outstanding questions on whether ethylene application promotes or inhibits receptor kinase activity of the ethylene receptors. Elucidating the complexity in auxin, cytokinin, and ethylene crosstalk requires a combined experimental and systems modeling approach. We evaluate important modeling efforts for establishing how crosstalk between auxin, cytokinin, and ethylene regulates patterning in root development. We discuss how a novel methodology that iteratively combines experiments with systems modeling analysis is essential for elucidating the complexity in crosstalk of auxin, cytokinin, and ethylene in root development. Finally, we discuss the future challenges from a combined experimental and modeling perspective.
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Affiliation(s)
- Junli Liu
- Department of Biosciences, Durham University, South Road, Durham DH1 3LE, UK
| | - Simon Moore
- Department of Biosciences, Durham University, South Road, Durham DH1 3LE, UK
| | - Chunli Chen
- College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
| | - Keith Lindsey
- Department of Biosciences, Durham University, South Road, Durham DH1 3LE, UK.
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24
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Xu W, Huang W. Calcium-Dependent Protein Kinases in Phytohormone Signaling Pathways. Int J Mol Sci 2017; 18:ijms18112436. [PMID: 29156607 PMCID: PMC5713403 DOI: 10.3390/ijms18112436] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Revised: 11/07/2017] [Accepted: 11/12/2017] [Indexed: 02/06/2023] Open
Abstract
Calcium-dependent protein kinases (CPKs/CDPKs) are Ca2+-sensors that decode Ca2+ signals into specific physiological responses. Research has reported that CDPKs constitute a large multigene family in various plant species, and play diverse roles in plant growth, development, and stress responses. Although numerous CDPKs have been exhaustively studied, and many of them have been found to be involved in plant hormone biosynthesis and response mechanisms, a comprehensive overview of the manner in which CDPKs participate in phytohormone signaling pathways, regulating nearly all aspects of plant growth, has not yet been undertaken. In this article, we reviewed the structure of CDPKs and the mechanism of their subcellular localization. Some CDPKs were elucidated to influence the intracellular localization of their substrates. Since little work has been done on the interaction between CDPKs and cytokinin signaling pathways, or on newly defined phytohormones such as brassinosteroids, strigolactones and salicylic acid, this paper mainly focused on discussing the integral associations between CDPKs and five plant hormones: auxins, gibberellins, ethylene, jasmonates, and abscisic acid. A perspective on future work is provided at the end.
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Affiliation(s)
- Wuwu Xu
- State Key Laboratory of Hybrid Rice, Key Laboratory for Research and Utilization of Heterosis in Indica Rice, the Ministry of Agriculture, The Yangtze River Valley Hybrid Rice Collaboration & Innovation Center, College of Life Sciences, Wuhan University, Wuhan 430072, China.
| | - Wenchao Huang
- State Key Laboratory of Hybrid Rice, Key Laboratory for Research and Utilization of Heterosis in Indica Rice, the Ministry of Agriculture, The Yangtze River Valley Hybrid Rice Collaboration & Innovation Center, College of Life Sciences, Wuhan University, Wuhan 430072, China.
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25
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Fàbregas N, Formosa-Jordan P, Ibañes M, Caño-Delgado AI. Experimental and Theoretical Methods to Approach the Study of Vascular Patterning in the Plant Shoot. Methods Mol Biol 2017; 1544:3-19. [PMID: 28050824 DOI: 10.1007/978-1-4939-6722-3_1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The plant vascular system provides transport and mechanical support functions that are essential for suitable plant growth and development. In Arabidopsis thaliana (Arabidopsis), the vascular tissues at the shoot inflorescence stems are disposed in organized vascular bundles. The vascular patterning emergence and development within the shoot inflorescence stems is under the control of plant growth regulators (De Rybel et al., Nat Rev Mol Cell Biol 17:30-40, 2016; Caño-Delgado et al., Annu Rev Cell Dev Biol 26:605-637, 2010). By using a combined approach of experimental methods for vascular tissues visualization and quantification together with theoretical methods through mathematical and computational modeling, we have reported that auxin transport and brassinosteroid signaling play complementary roles in the formation of the periodic vascular patterning in the shoot (Ibañes et al., Proc Natl Acad Sci U S A 106:13630-13635, 2009; Fàbregas et al., Plant Signal Behav 5:903-906, 2010; Fàbregas et al., PLoS Genet 11:e1005183, 2015). Here, we report the methodology for the interdisciplinary analysis of the shoot vascular patterning in the plant model Arabidopsis into a handle procedure for visualization, quantification, data analysis, and modeling implementation.
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Affiliation(s)
- Norma Fàbregas
- Department of Molecular Genetics, Centre for Research in Agricultural Genomics (CRAG) CSIC-IRTA-UAB-UB, Barcelona, Spain
| | - Pau Formosa-Jordan
- The Sainsbury Laboratory, University of Cambridge, Bateman Street, Cambridge, CB2 1LR, UK
| | - Marta Ibañes
- Department of Condensed Matter Physics, University of Barcelona, Barcelona, Spain
| | - Ana I Caño-Delgado
- Department of Molecular Genetics, Centre for Research in Agricultural Genomics (CRAG) CSIC-IRTA-UAB-UB, Barcelona, Spain.
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26
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Kanayama Y. Sugar Metabolism and Fruit Development in the Tomato. THE HORTICULTURE JOURNAL 2017; 86:417-425. [PMID: 0 DOI: 10.2503/hortj.okd-ir01] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
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27
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Morales-Tapia A, Cruz-Ramírez A. Computational Modeling of Auxin: A Foundation for Plant Engineering. FRONTIERS IN PLANT SCIENCE 2016; 7:1881. [PMID: 28066453 PMCID: PMC5168462 DOI: 10.3389/fpls.2016.01881] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 11/29/2016] [Indexed: 05/29/2023]
Abstract
Since the development of agriculture, humans have relied on the cultivation of plants to satisfy our increasing demand for food, natural products, and other raw materials. As we understand more about plant development, we can better manipulate plants to fulfill our particular needs. Auxins are a class of simple metabolites that coordinate many developmental activities like growth and the appearance of functional structures in plants. Computational modeling of auxin has proven to be an excellent tool in elucidating many mechanisms that underlie these developmental events. Due to the complexity of these mechanisms, current modeling efforts are concerned only with single phenomena focused on narrow spatial and developmental contexts; but a general model of plant development could be assembled by integrating the insights from all of them. In this perspective, we summarize the current collection of auxin-driven computational models, focusing on how they could come together into a single model for plant development. A model of this nature would allow researchers to test hypotheses in silico and yield accurate predictions about the behavior of a plant under a given set of physical and biochemical constraints. It would also provide a solid foundation toward the establishment of plant engineering, a proposed discipline intended to enable the design and production of plants that exhibit an arbitrarily defined set of features.
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Abstract
Plant hormones (phytohormones) integrate endogenous and exogenous signals thus synchronizing plant growth with environmental and developmental changes. Similar to animals, phytohormones have distinct source and target tissues, hence controlled transport and focused targeting are required for their functions. Many evidences accumulated in the last years about the regulation of long-distance and directional transport of phytohormones. ATP-binding cassette (ABC) transporters turned out to play major roles in routing phytohormones not only in the plant body but also towards the outer environment. The ABCG-type proteins ABCG25 and ABCG40 are high affinity abscisic acid (ABA) transporters. ABCG14 is highly co-expressed with cytokinin biosynthesis and is the major root-to-shoot cytokinin transporter. Pleiotropic drug resistance1 (PDR1) from Petunia hybrida transports strigolactones (SLs) from the root tip to the plant shoot but also outside to the rhizosphere, where SLs are the main attractants to mycorrhizal fungi. Last but not least, ABCG36 and ABCG37 possibly play a dual role in coumarine and IBA transport.
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PPP1, a plant-specific regulator of transcription controls Arabidopsis development and PIN expression. Sci Rep 2016; 6:32196. [PMID: 27553690 PMCID: PMC4995536 DOI: 10.1038/srep32196] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 08/04/2016] [Indexed: 01/31/2023] Open
Abstract
Directional transport of auxin is essential for plant development, with PIN auxin transport proteins representing an integral part of the machinery that controls hormone distribution. However, unlike the rapidly emerging framework of molecular determinants regulating PIN protein abundance and subcellular localization, insights into mechanisms controlling PIN transcription are still limited. Here we describe PIN2 PROMOTER BINDING PROTEIN 1 (PPP1), an evolutionary conserved plant-specific DNA binding protein that acts on transcription of PIN genes. Consistent with PPP1 DNA-binding activity, PPP1 reporter proteins are nuclear localized and analysis of PPP1 null alleles and knockdown lines indicated a function as a positive regulator of PIN expression. Furthermore, we show that ppp1 pleiotropic mutant phenotypes are partially reverted by PIN overexpression, and results are presented that underline a role of PPP1-PIN promoter interaction in PIN expression control. Collectively, our findings identify an elementary, thus far unknown, plant-specific DNA-binding protein required for post-embryonic plant development, in general, and correct expression of PIN genes, in particular.
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30
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Boot KJM, Hille SC, Libbenga KR, Peletier LA, van Spronsen PC, van Duijn B, Offringa R. Modelling the dynamics of polar auxin transport in inflorescence stems of Arabidopsis thaliana. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:649-666. [PMID: 26531101 PMCID: PMC4737066 DOI: 10.1093/jxb/erv471] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The polar transport of the plant hormone auxin has been the subject of many studies, several involving mathematical modelling. Unfortunately, most of these models have not been experimentally verified. Here we present experimental measurements of long-distance polar auxin transport (PAT) in segments of inflorescence stems of Arabidopsis thaliana together with a descriptive mathematical model that was developed from these data. It is based on a general advection-diffusion equation for auxin density, as suggested by the chemiosmotic theory, but is extended to incorporate both immobilization of auxin and exchange with the surrounding tissue of cells involved in PAT, in order to account for crucial observations. We found that development of the present model assisted effectively in the analysis of experimental observations. As an example, we discuss the analysis of a quadruple mutant for all four AUX1/LAX1-LAX3 influx carriers genes. We found a drastic change in the parameters governing the exchange of PAT channels with the surrounding tissue, whereas the velocity was still of the order of magnitude of the wild type. In addition, the steady-state flux of auxin through the PAT system of the mutant did not exhibit a saturable component, as we found for the wild type, suggesting that the import carriers are responsible for the saturable component in the wild type. In the accompanying Supplementary data available at JXB online, we describe in more detail the data-driven development of the model, review and derive predictions from a mathematical model of the chemiosmotic theory, and explore relationships between parameters in our model and processes and parameters at the cellular level.
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Affiliation(s)
- Kees J M Boot
- Plant Biodynamics Laboratory, Institute of Biology Leiden, Leiden University, 2333 EB Leiden, The Netherlands Department of Molecular and Developmental Genetics, Institute of Biology Leiden, Leiden University, 2333 EB Leiden, The Netherlands
| | - Sander C Hille
- Plant Biodynamics Laboratory, Institute of Biology Leiden, Leiden University, 2333 EB Leiden, The Netherlands Mathematical Institute, Leiden University, 2333CA, Leiden, The Netherlands
| | - Kees R Libbenga
- Plant Biodynamics Laboratory, Institute of Biology Leiden, Leiden University, 2333 EB Leiden, The Netherlands
| | - Lambertus A Peletier
- Plant Biodynamics Laboratory, Institute of Biology Leiden, Leiden University, 2333 EB Leiden, The Netherlands Mathematical Institute, Leiden University, 2333CA, Leiden, The Netherlands
| | - Paulina C van Spronsen
- Department of Molecular and Developmental Genetics, Institute of Biology Leiden, Leiden University, 2333 EB Leiden, The Netherlands
| | - Bert van Duijn
- Plant Biodynamics Laboratory, Institute of Biology Leiden, Leiden University, 2333 EB Leiden, The Netherlands Fytagoras, 2333 EB Leiden, The Netherlands
| | - Remko Offringa
- Plant Biodynamics Laboratory, Institute of Biology Leiden, Leiden University, 2333 EB Leiden, The Netherlands Department of Molecular and Developmental Genetics, Institute of Biology Leiden, Leiden University, 2333 EB Leiden, The Netherlands
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31
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Moore S, Zhang X, Mudge A, Rowe JH, Topping JF, Liu J, Lindsey K. Spatiotemporal modelling of hormonal crosstalk explains the level and patterning of hormones and gene expression in Arabidopsis thaliana wild-type and mutant roots. THE NEW PHYTOLOGIST 2015; 207:1110-22. [PMID: 25906686 PMCID: PMC4539600 DOI: 10.1111/nph.13421] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 03/20/2015] [Indexed: 05/08/2023]
Abstract
Patterning in Arabidopsis root development is coordinated via a localized auxin concentration maximum in the root tip, requiring the regulated expression of specific genes. However, little is known about how hormone and gene expression patterning is generated. Using a variety of experimental data, we develop a spatiotemporal hormonal crosstalk model that describes the integrated action of auxin, ethylene and cytokinin signalling, the POLARIS protein, and the functions of PIN and AUX1 auxin transporters. We also conduct novel experiments to confirm our modelling predictions. The model reproduces auxin patterning and trends in wild-type and mutants; reveals that coordinated PIN and AUX1 activities are required to generate correct auxin patterning; correctly predicts shoot to root auxin flux, auxin patterning in the aux1 mutant, the amounts of cytokinin, ethylene and PIN protein, and PIN protein patterning in wild-type and mutant roots. Modelling analysis further reveals how PIN protein patterning is related to the POLARIS protein through ethylene signalling. Modelling prediction of the patterning of POLARIS expression is confirmed experimentally. Our combined modelling and experimental analysis reveals that a hormonal crosstalk network regulates the emergence of patterns and levels of hormones and gene expression in wild-type and mutants.
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Affiliation(s)
- Simon Moore
- The Integrative Cell Biology Laboratory, School of Biological and Biomedical Sciences, Durham UniversitySouth Road, Durham, DH1 3LE, UK
| | - Xiaoxian Zhang
- School of Engineering, The University of LiverpoolBrownlow Street, Liverpool, L69 3GQ, UK
| | - Anna Mudge
- The Integrative Cell Biology Laboratory, School of Biological and Biomedical Sciences, Durham UniversitySouth Road, Durham, DH1 3LE, UK
| | - James H Rowe
- The Integrative Cell Biology Laboratory, School of Biological and Biomedical Sciences, Durham UniversitySouth Road, Durham, DH1 3LE, UK
| | - Jennifer F Topping
- The Integrative Cell Biology Laboratory, School of Biological and Biomedical Sciences, Durham UniversitySouth Road, Durham, DH1 3LE, UK
| | - Junli Liu
- The Integrative Cell Biology Laboratory, School of Biological and Biomedical Sciences, Durham UniversitySouth Road, Durham, DH1 3LE, UK
| | - Keith Lindsey
- The Integrative Cell Biology Laboratory, School of Biological and Biomedical Sciences, Durham UniversitySouth Road, Durham, DH1 3LE, UK
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Turchi L, Baima S, Morelli G, Ruberti I. Interplay of HD-Zip II and III transcription factors in auxin-regulated plant development. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:5043-53. [PMID: 25911742 DOI: 10.1093/jxb/erv174] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The homeodomain-leucine zipper (HD-Zip) class of transcription factors is unique to plants. HD-Zip proteins bind to DNA exclusively as dimers recognizing dyad symmetric sequences and act as positive or negative regulators of gene expression. On the basis of sequence homology in the HD-Zip DNA-binding domain, HD-Zip proteins have been grouped into four families (HD-Zip I-IV). Each HD-Zip family can be further divided into subfamilies containing paralogous genes that have arisen through genome duplication. Remarkably, all the members of the HD-Zip IIγ and -δ clades are regulated by light quality changes that induce in the majority of the angiosperms the shade-avoidance response, a process regulated at multiple levels by auxin. Intriguingly, it has recently emerged that, apart from their function in shade avoidance, the HD-Zip IIγ and -δ transcription factors control several auxin-regulated developmental processes, including apical embryo patterning, lateral organ polarity, and gynoecium development, in a white-light environment. This review presents recent advances in our understanding of HD-Zip II protein function in plant development, with particular emphasis on the impact of loss-of-function HD-Zip II mutations on auxin distribution and response. The review also describes evidence demonstrating that HD-Zip IIγ and -δ genes are directly and positively regulated by HD-Zip III transcription factors, primary determinants of apical shoot development, known to control the expression of several auxin biosynthesis, transport, and response genes. Finally, the interplay between HD-Zip II and III transcription factors in embryo apical patterning and organ polarity is discussed.
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Affiliation(s)
- L Turchi
- Institute of Molecular Biology and Pathology, National Research Council, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - S Baima
- Food and Nutrition Research Centre, Agricultural Research Council, Via Ardeatina 546, 00178 Rome, Italy
| | - G Morelli
- Food and Nutrition Research Centre, Agricultural Research Council, Via Ardeatina 546, 00178 Rome, Italy
| | - I Ruberti
- Institute of Molecular Biology and Pathology, National Research Council, Piazzale Aldo Moro 5, 00185 Rome, Italy
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33
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Kasprzewska A, Carter R, Swarup R, Bennett M, Monk N, Hobbs JK, Fleming A. Auxin influx importers modulate serration along the leaf margin. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 83:705-18. [PMID: 26111009 PMCID: PMC4949643 DOI: 10.1111/tpj.12921] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 06/15/2015] [Indexed: 05/06/2023]
Abstract
Leaf shape in Arabidopsis is modulated by patterning events in the margin that utilize a PIN-based auxin exporter/CUC2 transcription factor system to define regions of promotion and retardation of growth, leading to morphogenesis. In addition to auxin exporters, leaves also express auxin importers, notably members of the AUX1/LAX family. In contrast to their established roles in embryogenesis, lateral root and leaf initiation, the function of these transporters in leaf development is poorly understood. We report that three of these genes (AUX1, LAX1 and LAX2) show specific and dynamic patterns of expression during early leaf development in Arabidopsis, and that loss of expression of all three genes is required for observation of a phenotype in which morphogenesis (serration) is decreased. We used these expression patterns and mutant phenotypes to develop a margin-patterning model that incorporates an AUX1/LAX1/LAX2 auxin import module that influences the extent of leaf serration. Testing of this model by margin-localized expression of axr3-1 (AXR17) provides further insight into the role of auxin in leaf morphogenesis.
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Affiliation(s)
- Ania Kasprzewska
- Department of Animal and Plant Science, University of Sheffield, Sheffield, S10 2TN, UK
| | - Ross Carter
- Department of Animal and Plant Science, University of Sheffield, Sheffield, S10 2TN, UK
- Department of Physics & Astronomy, University of Sheffield, Sheffield, S10 2TN, UK
| | - Ranjan Swarup
- Centre for Plant Integrative Biology, University of Nottingham, Sutton Bonington, LE12 5RD, UK
| | - Malcolm Bennett
- Centre for Plant Integrative Biology, University of Nottingham, Sutton Bonington, LE12 5RD, UK
| | - Nick Monk
- School of Mathematics and Statistics, University of Sheffield, Sheffield, S10 2TN, UK
| | - Jamie K Hobbs
- Department of Physics & Astronomy, University of Sheffield, Sheffield, S10 2TN, UK
| | - Andrew Fleming
- Department of Animal and Plant Science, University of Sheffield, Sheffield, S10 2TN, UK
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Fàbregas N, Formosa-Jordan P, Confraria A, Siligato R, Alonso JM, Swarup R, Bennett MJ, Mähönen AP, Caño-Delgado AI, Ibañes M. Auxin influx carriers control vascular patterning and xylem differentiation in Arabidopsis thaliana. PLoS Genet 2015; 11:e1005183. [PMID: 25922946 PMCID: PMC4414528 DOI: 10.1371/journal.pgen.1005183] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 03/29/2015] [Indexed: 12/23/2022] Open
Abstract
Auxin is an essential hormone for plant growth and development. Auxin influx carriers AUX1/LAX transport auxin into the cell, while auxin efflux carriers PIN pump it out of the cell. It is well established that efflux carriers play an important role in the shoot vascular patterning, yet the contribution of influx carriers to the shoot vasculature remains unknown. Here, we combined theoretical and experimental approaches to decipher the role of auxin influx carriers in the patterning and differentiation of vascular tissues in the Arabidopsis inflorescence stem. Our theoretical analysis predicts that influx carriers facilitate periodic patterning and modulate the periodicity of auxin maxima. In agreement, we observed fewer and more spaced vascular bundles in quadruple mutants plants of the auxin influx carriers aux1lax1lax2lax3. Furthermore, we show AUX1/LAX carriers promote xylem differentiation in both the shoot and the root tissues. Influx carriers increase cytoplasmic auxin signaling, and thereby differentiation. In addition to this cytoplasmic role of auxin, our computational simulations propose a role for extracellular auxin as an inhibitor of xylem differentiation. Altogether, our study shows that auxin influx carriers AUX1/LAX regulate vascular patterning and differentiation in plants.
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Affiliation(s)
- Norma Fàbregas
- Department of Molecular Genetics, Centre for Research in Agricultural Genomics (CRAG) CSIC-IRTA-UAB-UB, Barcelona, Spain
| | - Pau Formosa-Jordan
- Department of Structure and Constituents of Matter, Faculty of Physics, University of Barcelona, Barcelona, Spain
| | - Ana Confraria
- Department of Molecular Genetics, Centre for Research in Agricultural Genomics (CRAG) CSIC-IRTA-UAB-UB, Barcelona, Spain
| | - Riccardo Siligato
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
- Department of Biosciences, University of Helsinki, Helsinki, Finland
| | - Jose M. Alonso
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina, United States of America
| | - Ranjan Swarup
- School of Biosciences and Centre for Plant Integrative Biology, University of Nottingham, Nottingham, United Kingdom
| | - Malcolm J. Bennett
- School of Biosciences and Centre for Plant Integrative Biology, University of Nottingham, Nottingham, United Kingdom
| | - Ari Pekka Mähönen
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
- Department of Biosciences, University of Helsinki, Helsinki, Finland
| | - Ana I. Caño-Delgado
- Department of Molecular Genetics, Centre for Research in Agricultural Genomics (CRAG) CSIC-IRTA-UAB-UB, Barcelona, Spain
| | - Marta Ibañes
- Department of Structure and Constituents of Matter, Faculty of Physics, University of Barcelona, Barcelona, Spain
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35
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Feller C, Farcot E, Mazza C. Self-organization of plant vascular systems: claims and counter-claims about the flux-based auxin transport model. PLoS One 2015; 10:e0118238. [PMID: 25734327 PMCID: PMC4348546 DOI: 10.1371/journal.pone.0118238] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Accepted: 01/09/2015] [Indexed: 12/02/2022] Open
Abstract
The plant hormone auxin plays a central role in growth and morphogenesis. In shoot apical meristems, auxin flux is polarized through its interplay with PIN proteins. Concentration-based mathematical models of the flux can explain some aspects of phyllotaxis for the L1 surface layer, where auxin accumulation points act as sinks and develop into primordia. The picture differs in the interior of the meristem, where the primordia act as auxin sources, leading to the initiation of the vascular system. Self-organization of the auxin flux involves large numbers of molecules and is difficult to treat by intuitive reasoning alone; mathematical models are therefore vital to understand these phenomena. We consider a leading computational model based on the so-called flux hypothesis. This model has been criticized and extended in various ways. One of the basic counter-arguments is that simulations yield auxin concentrations inside canals that are lower than those seen experimentally. Contrary to what is claimed in the literature, we show that the model can lead to higher concentrations within canals for significant parameter regimes. We then study the model in the usual case where the response function Φ defining the model is quadratic and unbounded, and show that the steady state vascular patterns are formed of loopless directed trees. Moreover, we show that PIN concentrations can diverge in finite time, thus explaining why previous simulation studies introduced cut-offs which force the system to have bounded PIN concentrations. Hence, contrary to previous claims, extreme PIN concentrations are not due to numerical problems but are intrinsic to the model. On the other hand, we show that PIN concentrations remain bounded for bounded Φ, and simulations show that in this case, loops can emerge at steady state.
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Affiliation(s)
- Chrystel Feller
- Department of Mathematics and Swiss Institute of Bioinformatics, University of Fribourg, Fribourg, Switzerland
| | - Etienne Farcot
- School of Mathematical Sciences, University of Nottingham, Nottingham, UK
| | - Christian Mazza
- Department of Mathematics and Swiss Institute of Bioinformatics, University of Fribourg, Fribourg, Switzerland
- * E-mail:
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36
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Kramer EM, Ackelsberg EM. Auxin metabolism rates and implications for plant development. FRONTIERS IN PLANT SCIENCE 2015; 6:150. [PMID: 25852709 PMCID: PMC4362085 DOI: 10.3389/fpls.2015.00150] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 02/24/2015] [Indexed: 05/08/2023]
Abstract
Studies of auxin metabolism rarely express their results as a metabolic rate, although the data obtained would often permit such a calculation to be made. We analyze data from 31 previously published papers to quantify the rates of auxin biosynthesis, conjugation, conjugate hydrolysis, and catabolism in seed plants. Most metabolic pathways have rates in the range 10 nM/h-1 μM/h, with the exception of auxin conjugation, which has rates as high as ~100 μM/h. The high rates of conjugation suggest that auxin metabolic sinks may be very small, perhaps as small as a single cell. By contrast, the relatively low rate of auxin biosynthesis requires plants to conserve and recycle auxin during long-distance transport. The consequences for plant development are discussed.
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Affiliation(s)
- Eric M. Kramer
- *Correspondence: Eric M. Kramer, Bard College at Simon's Rock, 84 Alford Road, Great Barrington, MA 01230, USA
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37
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Bimodal regulation of ICR1 levels generates self-organizing auxin distribution. Proc Natl Acad Sci U S A 2014; 111:E5471-9. [PMID: 25468974 DOI: 10.1073/pnas.1413918111] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Auxin polar transport, local maxima, and gradients have become an important model system for studying self-organization. Auxin distribution is regulated by auxin-dependent positive feedback loops that are not well-understood at the molecular level. Previously, we showed the involvement of the RHO of Plants (ROP) effector INTERACTOR of CONSTITUTIVELY active ROP 1 (ICR1) in regulation of auxin transport and that ICR1 levels are posttranscriptionally repressed at the site of maximum auxin accumulation at the root tip. Here, we show that bimodal regulation of ICR1 levels by auxin is essential for regulating formation of auxin local maxima and gradients. ICR1 levels increase concomitant with increase in auxin response in lateral root primordia, cotyledon tips, and provascular tissues. However, in the embryo hypophysis and root meristem, when auxin exceeds critical levels, ICR1 is rapidly destabilized by an SCF(TIR1/AFB) [SKP, Cullin, F-box (transport inhibitor response 1/auxin signaling F-box protein)]-dependent auxin signaling mechanism. Furthermore, ectopic expression of ICR1 in the embryo hypophysis resulted in reduction of auxin accumulation and concomitant root growth arrest. ICR1 disappeared during root regeneration and lateral root initiation concomitantly with the formation of a local auxin maximum in response to external auxin treatments and transiently after gravitropic stimulation. Destabilization of ICR1 was impaired after inhibition of auxin transport and signaling, proteasome function, and protein synthesis. A mathematical model based on these findings shows that an in vivo-like auxin distribution, rootward auxin flux, and shootward reflux can be simulated without assuming preexisting tissue polarity. Our experimental results and mathematical modeling indicate that regulation of auxin distribution is tightly associated with auxin-dependent ICR1 levels.
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38
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Rutschow HL, Baskin TI, Kramer EM. The carrier AUXIN RESISTANT (AUX1) dominates auxin flux into Arabidopsis protoplasts. THE NEW PHYTOLOGIST 2014; 204:536-544. [PMID: 25039492 DOI: 10.1111/nph.12933] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2014] [Accepted: 06/15/2014] [Indexed: 05/22/2023]
Abstract
The ability of the plant hormone auxin to enter a cell is critical to auxin transport and signaling. Auxin can cross the cell membrane by diffusion or via auxin-specific influx carriers. There is little knowledge of the magnitudes of these fluxes in plants. Radiolabeled auxin uptake was measured in protoplasts isolated from roots of Arabidopsis thaliana. This was done for the wild-type, under treatments with additional unlabeled auxin to saturate the influx carriers, and for the influx carrier mutant auxin resistant 1 (aux1). We also used flow cytometry to quantify the relative abundance of cells expressing AUX1-YFP in the assayed population. At pH 5.7, the majority of auxin influx into protoplasts - 75% - was mediated by the influx carrier AUX1. An additional 20% was mediated by other saturable carriers. The diffusive influx of auxin was essentially negligible at pH 5.7. The influx of auxin mediated by AUX1, expressed as a membrane permeability, was 1.5 ± 0.3 μm s(-1) . This value is comparable in magnitude to estimates of efflux permeability. Thus, auxin-transporting tissues can sustain relatively high auxin efflux and yet not become depleted of auxin.
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Affiliation(s)
- Heidi L Rutschow
- Biology Department, University of Massachusetts, Amherst, MA, 01003, USA
- Physics Department, Bard College at Simons Rock, Great Barrington, MA, 01230, USA
| | - Tobias I Baskin
- Biology Department, University of Massachusetts, Amherst, MA, 01003, USA
| | - Eric M Kramer
- Physics Department, Bard College at Simons Rock, Great Barrington, MA, 01230, USA
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39
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Retzer K, Butt H, Korbei B, Luschnig C. The far side of auxin signaling: fundamental cellular activities and their contribution to a defined growth response in plants. PROTOPLASMA 2014; 251:731-46. [PMID: 24221297 PMCID: PMC4059964 DOI: 10.1007/s00709-013-0572-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 10/15/2013] [Indexed: 05/04/2023]
Abstract
Recent years have provided us with spectacular insights into the biology of the plant hormone auxin, leaving the impression of a highly versatile molecule involved in virtually every aspect of plant development. A combination of genetics, biochemistry, and cell biology has established auxin signaling pathways, leading to the identification of two distinct modes of auxin perception and downstream regulatory cascades. Major targets of these signaling modules are components of the polar auxin transport machinery, mediating directional distribution of the phytohormone throughout the plant body, and decisively affecting plant development. Alterations in auxin transport, metabolism, or signaling that occur as a result of intrinsic as well as environmental stimuli, control adjustments in morphogenetic programs, giving rise to defined growth responses attributed to the activity of the phytohormone. Some of the results obtained from the analysis of auxin, however, do not fit coherently into a picture of highly specific signaling events, but rather suggest mutual interactions between auxin and fundamental cellular pathways, like the control of intracellular protein sorting or translation. Crosstalk between auxin and these basic determinants of cellular activity and how they might shape auxin effects in the control of morphogenesis are the subject of this review.
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Affiliation(s)
- Katarzyna Retzer
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, BOKU, Wien Muthgasse 18, 1190 Wien, Austria
| | - Haroon Butt
- Department of Biological Sciences, Forman Christian College, Ferozepur Road, Lahore, 54600 Pakistan
| | - Barbara Korbei
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, BOKU, Wien Muthgasse 18, 1190 Wien, Austria
| | - Christian Luschnig
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, BOKU, Wien Muthgasse 18, 1190 Wien, Austria
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40
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Baima S, Forte V, Possenti M, Peñalosa A, Leoni G, Salvi S, Felici B, Ruberti I, Morelli G. Negative feedback regulation of auxin signaling by ATHB8/ACL5-BUD2 transcription module. MOLECULAR PLANT 2014; 7:1006-1025. [PMID: 24777988 DOI: 10.1093/mp/ssu051] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The role of auxin as main regulator of vascular differentiation is well established, and a direct correlation between the rate of xylem differentiation and the amount of auxin reaching the (pro)cambial cells has been proposed. It has been suggested that thermospermine produced by ACAULIS5 (ACL5) and bushy and dwarf2 (BUD2) is one of the factors downstream to auxin contributing to the regulation of this process in Arabidopsis. Here, we provide an in-depth characterization of the mechanism through which ACL5 modulates xylem differentiation. We show that an increased level of ACL5 slows down xylem differentiation by negatively affecting the expression of homeodomain-leucine zipper (HD-ZIP) III and key auxin signaling genes. This mechanism involves the positive regulation of thermospermine biosynthesis by the HD-ZIP III protein Arabidopsis thaliana homeobox8 tightly controlling the expression of ACL5 and BUD2. In addition, we show that the HD-ZIP III protein REVOLUTA contributes to the increased leaf vascularization and long hypocotyl phenotype of acl5 likely by a direct regulation of auxin signaling genes such as like auxin resistant2 (LAX2) and LAX3. We propose that proper formation and differentiation of xylem depend on a balance between positive and negative feedback loops operating through HD-ZIP III genes.
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Affiliation(s)
- Simona Baima
- Food and Nutrition Research Centre, Agricultural Research Council, Via Ardeatina 546, Rome 00178, Italy
| | - Valentina Forte
- Food and Nutrition Research Centre, Agricultural Research Council, Via Ardeatina 546, Rome 00178, Italy
| | - Marco Possenti
- Food and Nutrition Research Centre, Agricultural Research Council, Via Ardeatina 546, Rome 00178, Italy
| | - Andrés Peñalosa
- Food and Nutrition Research Centre, Agricultural Research Council, Via Ardeatina 546, Rome 00178, Italy
| | - Guido Leoni
- Food and Nutrition Research Centre, Agricultural Research Council, Via Ardeatina 546, Rome 00178, Italy; Present address: Department of Physics, Sapienza University of Rome, P.le A. Moro 5, 00185, Rome, Italy
| | - Sergio Salvi
- Food and Nutrition Research Centre, Agricultural Research Council, Via Ardeatina 546, Rome 00178, Italy
| | - Barbara Felici
- Food and Nutrition Research Centre, Agricultural Research Council, Via Ardeatina 546, Rome 00178, Italy; Present address: Soil-Plant System Studies Research Centre, Agricultural Research Council, Via della Navicella 2-4, 00184, Rome, Italy
| | - Ida Ruberti
- Institute of Biology, Molecular Medicine and NanoBiotechnology, National Research Council, P.le A. Moro 5, Rome 00185, Italy
| | - Giorgio Morelli
- Food and Nutrition Research Centre, Agricultural Research Council, Via Ardeatina 546, Rome 00178, Italy.
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Suzuki H, Matano N, Nishimura T, Koshiba T. A 2,4-dichlorophenoxyacetic acid analog screened using a maize coleoptile system potentially inhibits indole-3-acetic acid influx in Arabidopsis thaliana. PLANT SIGNALING & BEHAVIOR 2014; 9:29077. [PMID: 24800738 PMCID: PMC4091417 DOI: 10.4161/psb.29077] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Revised: 04/30/2014] [Accepted: 04/30/2014] [Indexed: 05/30/2023]
Abstract
Studies using inhibitors of indole-3-acetic acid (IAA) transport, not only for efflux but influx carriers, provide many aspects of auxin physiology in plants. 1-Naphtoxyacetic acid (1-NOA), an analog of the synthetic auxin 1-N-naphtalene acetic acid (NAA), inhibits the IAA influx carrier AUX1. However, 1-NOA also shows auxin activity because of its structural similarity to NAA. In this study, we have identified another candidate inhibitor of the IAA influx carrier. The compound, "7-B3; ethyl 2-[(2-chloro-4-nitrophenyl)thio]acetate," is a 2,4-dichlorophenoxyacetic acid (2,4-D) analog. At high concentrations (> 300 µM), 7-B3 slightly reduced IAA transport and tropic curvature of maize coleoptiles, whereas lower concentrations had almost no effect. We have analyzed the effects of 7-B3 on Arabidopsis thaliana seedlings. 7-B3 rescued the 2,4-D-inhibited root elongation, but not the NAA-inhibited root elongation. The effect of 7-B3 was weaker than that of 1-NOA. Both 1-NOA and 7-B3 inhibited DR5::GUS expression induced by IAA and 2,4-D, but not that induced by NAA. At high concentrations, 1-NOA exhibited auxin activity, but 7-B3 did not. Furthermore, 7-B3 inhibited apical hook formation in etiolated seedlings more effectively than did 1-NOA. These results indicate that 7-B3 is a potential inhibitor of IAA influx that has almost no effect on IAA efflux or auxin signaling.
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Band LR, Wells DM, Fozard JA, Ghetiu T, French AP, Pound MP, Wilson MH, Yu L, Li W, Hijazi HI, Oh J, Pearce SP, Perez-Amador MA, Yun J, Kramer E, Alonso JM, Godin C, Vernoux T, Hodgman TC, Pridmore TP, Swarup R, King JR, Bennett MJ. Systems analysis of auxin transport in the Arabidopsis root apex. THE PLANT CELL 2014; 26:862-75. [PMID: 24632533 PMCID: PMC4001398 DOI: 10.1105/tpc.113.119495] [Citation(s) in RCA: 148] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Revised: 01/06/2014] [Accepted: 02/14/2014] [Indexed: 05/17/2023]
Abstract
Auxin is a key regulator of plant growth and development. Within the root tip, auxin distribution plays a crucial role specifying developmental zones and coordinating tropic responses. Determining how the organ-scale auxin pattern is regulated at the cellular scale is essential to understanding how these processes are controlled. In this study, we developed an auxin transport model based on actual root cell geometries and carrier subcellular localizations. We tested model predictions using the DII-VENUS auxin sensor in conjunction with state-of-the-art segmentation tools. Our study revealed that auxin efflux carriers alone cannot create the pattern of auxin distribution at the root tip and that AUX1/LAX influx carriers are also required. We observed that AUX1 in lateral root cap (LRC) and elongating epidermal cells greatly enhance auxin's shootward flux, with this flux being predominantly through the LRC, entering the epidermal cells only as they enter the elongation zone. We conclude that the nonpolar AUX1/LAX influx carriers control which tissues have high auxin levels, whereas the polar PIN carriers control the direction of auxin transport within these tissues.
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Affiliation(s)
- Leah R. Band
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - Darren M. Wells
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - John A. Fozard
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - Teodor Ghetiu
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - Andrew P. French
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - Michael P. Pound
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - Michael H. Wilson
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - Lei Yu
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - Wenda Li
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - Hussein I. Hijazi
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - Jaesung Oh
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - Simon P. Pearce
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - Miguel A. Perez-Amador
- Instituto de Biología Molecular y Celular de Plantas, Universidad Politécnica de Valencia–Consejo Superior de Investigaciones Científicas, Ciudad Politécnica de la Innovación, 46022 Valencia, Spain
| | - Jeonga Yun
- Department of Genetics, North Carolina State University, Raleigh, North Carolina 27695
| | - Eric Kramer
- Physics Department, Bard College at Simon’s Rock, Great Barrington, Massachusetts 01230
| | - Jose M. Alonso
- Department of Genetics, North Carolina State University, Raleigh, North Carolina 27695
| | - Christophe Godin
- Virtual Plants Project Team, Unité Mixte de Recherche, Amélioration Génétique des Plantes Méditerranéennes et Tropicales, Institut National de Recherche en Informatique et en Automatique/Centre de Coopération Internationale en Recherche Agronomique pour le Développement, 34095 Montpellier, France
| | - Teva Vernoux
- Laboratoire de Reproduction et Developpement des Plantes, CNRS, INRA, Ecole Normale Supérieure Lyon, Université Claude Bernard Lyon 1, Université de Lyon, 69364 Lyon, France
| | - T. Charlie Hodgman
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - Tony P. Pridmore
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - Ranjan Swarup
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - John R. King
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
| | - Malcolm J. Bennett
- Centre for Plant Integrative Biology, University of Nottingham, Nottingham LE12 5RD, United Kingdom
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43
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Kierzkowski D, Lenhard M, Smith R, Kuhlemeier C. Interaction between meristem tissue layers controls phyllotaxis. Dev Cell 2013; 26:616-28. [PMID: 24091013 DOI: 10.1016/j.devcel.2013.08.017] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Revised: 06/30/2013] [Accepted: 08/22/2013] [Indexed: 01/03/2023]
Abstract
Phyllotaxis and vein formation are among the most conspicuous patterning processes in plants. The expression and polarization of the auxin efflux carrier PIN1 is the earliest marker for both processes, with mathematical models indicating that PIN1 can respond to auxin gradients and/or auxin flux. Here, we use cell-layer-specific PIN1 knockouts and partial complementation of auxin transport mutants to examine the interaction between phyllotactic patterning, which occurs primarily in the L1 surface layer of the meristem, and midvein specification in the inner tissues. We show that PIN1 expression in the L1 is sufficient for correct organ positioning, as long as the L1-specific influx carriers are present. Thus, differentiation of inner tissues can proceed without PIN1 or any of the known polar transporters. On theoretical grounds, we suggest that canalization of auxin flux between an auxin source and an auxin sink may involve facilitated diffusion rather than polar transport.
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Affiliation(s)
- Daniel Kierzkowski
- Institute of Plant Sciences, University of Bern, Bern CH-3013, Switzerland
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44
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Song W, Sun H, Li J, Gong X, Huang S, Zhu X, Zhang Y, Xu G. Auxin distribution is differentially affected by nitrate in roots of two rice cultivars differing in responsiveness to nitrogen. ANNALS OF BOTANY 2013; 112:1383-93. [PMID: 24095838 PMCID: PMC3806541 DOI: 10.1093/aob/mct212] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Accepted: 08/05/2013] [Indexed: 05/18/2023]
Abstract
BACKGROUND AND AIMS Although ammonium (NH4(+)) is the preferred form of nitrogen over nitrate (NO3(-)) for rice (Oryza sativa), lateral root (LR) growth in roots is enhanced by partial NO3(-) nutrition (PNN). The roles of auxin distribution and polar transport in LR formation in response to localized NO3(-) availability are not known. METHODS Time-course studies in a split-root experimental system were used to investigate LR development patterns, auxin distribution, polar auxin transport and expression of auxin transporter genes in LR zones in response to localized PNN in 'Nanguang' and 'Elio' rice cultivars, which show high and low responsiveness to NO3(-), respectively. Patterns of auxin distribution and the effects of polar auxin transport inhibitors were also examined in DR5::GUS transgenic plants. KEY RESULTS Initiation of LRs was enhanced by PNN after 7 d cultivation in 'Nanguang' but not in 'Elio'. Auxin concentration in the roots of 'Nanguang' increased by approx. 24 % after 5 d cultivation with PNN compared with NH4(+) as the sole nitrogen source, but no difference was observed in 'Elio'. More auxin flux into the LR zone in 'Nanguang' roots was observed in response to NO3(-) compared with NH4(+) treatment. A greater number of auxin influx and efflux transporter genes showed increased expression in the LR zone in response to PNN in 'Nanguang' than in 'Elio'. CONCLUSIONS The results indicate that higher NO3(-) responsiveness is associated with greater auxin accumulation in the LR zone and is strongly related to a higher rate of LR initiation in the cultivar 'Nanguang'.
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Affiliation(s)
- Wenjing Song
- Key Laboratory of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China
| | - Huwei Sun
- Key Laboratory of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China
| | - Jiao Li
- Key Laboratory of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China
| | - Xianpo Gong
- Key Laboratory of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China
| | - Shuangjie Huang
- Key Laboratory of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China
| | - Xudong Zhu
- Key Laboratory of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China
| | - Yali Zhang
- Key Laboratory of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 21008, China
- For correspondence.
| | - Guohua Xu
- Key Laboratory of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China
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45
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Sawchuk MG, Scarpella E. Polarity, continuity, and alignment in plant vascular strands. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2013; 55:824-834. [PMID: 23773763 DOI: 10.1111/jipb.12086] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 06/04/2013] [Indexed: 06/02/2023]
Abstract
Plant vascular cells are joined end to end along uninterrupted lines to connect shoot organs with roots; vascular strands are thus polar, continuous, and internally aligned. What controls the formation of vascular strands with these properties? The "auxin canalization hypothesis"-based on positive feedback between auxin flow through a cell and the cell's capacity for auxin transport-predicts the selection of continuous files of cells that transport auxin polarly, thus accounting for the polarity and continuity of vascular strands. By contrast, polar, continuous auxin transport-though required-is insufficient to promote internal alignment of vascular strands, implicating additional factors. The auxin canalization hypothesis was derived from the response of mature tissue to auxin application but is consistent with molecular and cellular events in embryo axis formation and shoot organ development. Objections to the hypothesis have been raised based on vascular organizations in callus tissue and shoot organs but seem unsupported by available evidence. Other objections call instead for further research; yet the inductive and orienting influence of auxin on continuous vascular differentiation remains unique.
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Affiliation(s)
- Megan G Sawchuk
- Department of Biological Sciences, University of Alberta, Edmonton Alberta, Canada, T6G 2E9
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46
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Panijel M, Chalupowicz L, Sessa G, Manulis-Sasson S, Barash I. Global regulatory networks control the hrp regulon of the gall-forming bacterium Pantoea agglomerans pv. gypsophilae. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2013; 26:1031-1043. [PMID: 23745675 DOI: 10.1094/mpmi-04-13-0097-r] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Gall formation by Pantoea agglomerans pv. gypsophilae is dependent on the hypersensitive response and pathogenicity (hrp) system. Previous studies demonstrated that PagR and PagI, regulators of the quorum-sensing system, induce expression of the hrp regulatory cascade (i.e., hrpXY, hrpS, and hrpL) that activates the HrpL regulon. Here, we isolated the genes of the Gac/Rsm global regulatory pathway (i.e., gacS, gacA, rsmB, and csrD) and of the post-transcriptional regulator rsmA. Our results demonstrate that PagR and PagI also upregulate expression of the Gac/Rsm pathway. PagR acts as a transcriptional activator of each of the hrp regulatory genes and gacA in a N-butanoyl-L-homoserine lactone-dependent manner as shown by gel shift experiments. Mutants of the Gac/Rsm genes or overexpression of rsmA significantly reduced Pantoea agglomerans virulence and colonization of gypsophila. Overexpression of rsmB sRNA abolished gall formation, colonization, and hypersensitive reaction on nonhost plants and prevented transcription of the hrp regulatory cascade, indicating a lack of functional type III secretion system. Expression of rsmB sRNA in the background of the csrD null mutant suggests that CsrD may act as a safeguard for preventing excessive production of rsmB sRNA. Results presented indicate that the hrp regulatory cascade is controlled directly by PagR and indirectly by RsmA, whereas deficiency in RsmA activity is epistatic to PagR induction.
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Affiliation(s)
- Mary Panijel
- Department of Molecular Biology and Ecology of Plants, Tel-Aviv University, Tel-Aviv, Israel
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47
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Fozard JA, Lucas M, King JR, Jensen OE. Vertex-element models for anisotropic growth of elongated plant organs. FRONTIERS IN PLANT SCIENCE 2013; 4:233. [PMID: 23847638 PMCID: PMC3706750 DOI: 10.3389/fpls.2013.00233] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 06/13/2013] [Indexed: 05/09/2023]
Abstract
New tools are required to address the challenge of relating plant hormone levels, hormone responses, wall biochemistry and wall mechanical properties to organ-scale growth. Current vertex-based models (applied in other contexts) can be unsuitable for simulating the growth of elongated organs such as roots because of the large aspect ratio of the cells, and these models fail to capture the mechanical properties of cell walls in sufficient detail. We describe a vertex-element model which resolves individual cells and includes anisotropic non-linear viscoelastic mechanical properties of cell walls and cell division whilst still being computationally efficient. We show that detailed consideration of the cell walls in the plane of a 2D simulation is necessary when cells have large aspect ratio, such as those in the root elongation zone of Arabidopsis thaliana, in order to avoid anomalous transverse swelling. We explore how differences in the mechanical properties of cells across an organ can result in bending and how cellulose microfibril orientation affects macroscale growth. We also demonstrate that the model can be used to simulate growth on realistic geometries, for example that of the primary root apex, using moderate computational resources. The model shows how macroscopic root shape can be sensitive to fine-scale cellular geometries.
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Affiliation(s)
- John A. Fozard
- Agricultural and Environmental Sciences, Centre for Plant Integrative Biology, School of Biosciences, University of NottinghamLeics, UK
| | - Mikaël Lucas
- Institut de Recherche pour le Développement, UMR DIADEMontpellier, France
| | - John R. King
- Agricultural and Environmental Sciences, Centre for Plant Integrative Biology, School of Biosciences, University of NottinghamLeics, UK
- School of Mathematical Sciences, University of NottinghamNottingham, UK
| | - Oliver E. Jensen
- Agricultural and Environmental Sciences, Centre for Plant Integrative Biology, School of Biosciences, University of NottinghamLeics, UK
- School of Mathematics, University of ManchesterManchester, UK
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48
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Jung JKH, McCouch S. Getting to the roots of it: Genetic and hormonal control of root architecture. FRONTIERS IN PLANT SCIENCE 2013; 4:186. [PMID: 23785372 PMCID: PMC3685011 DOI: 10.3389/fpls.2013.00186] [Citation(s) in RCA: 148] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Accepted: 05/22/2013] [Indexed: 05/17/2023]
Abstract
Root system architecture (RSA) - the spatial configuration of a root system - is an important developmental and agronomic trait, with implications for overall plant architecture, growth rate and yield, abiotic stress resistance, nutrient uptake, and developmental plasticity in response to environmental changes. Root architecture is modulated by intrinsic, hormone-mediated pathways, intersecting with pathways that perceive and respond to external, environmental signals. The recent development of several non-invasive 2D and 3D root imaging systems has enhanced our ability to accurately observe and quantify architectural traits on complex whole-root systems. Coupled with the powerful marker-based genotyping and sequencing platforms currently available, these root phenotyping technologies lend themselves to large-scale genome-wide association studies, and can speed the identification and characterization of the genes and pathways involved in root system development. This capability provides the foundation for examining the contribution of root architectural traits to the performance of crop varieties in diverse environments. This review focuses on our current understanding of the genes and pathways involved in determining RSA in response to both intrinsic and extrinsic (environmental) response pathways, and provides a brief overview of the latest root system phenotyping technologies and their potential impact on elucidating the genetic control of root development in plants.
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Affiliation(s)
| | - Susan McCouch
- Department of Plant Breeding and Genetics, Cornell UniversityIthaca, NY, USA
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49
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Rigó G, Ayaydin F, Tietz O, Zsigmond L, Kovács H, Páy A, Salchert K, Darula Z, Medzihradszky KF, Szabados L, Palme K, Koncz C, Cséplő Á. Inactivation of plasma membrane-localized CDPK-RELATED KINASE5 decelerates PIN2 exocytosis and root gravitropic response in Arabidopsis. THE PLANT CELL 2013; 25:1592-608. [PMID: 23673979 PMCID: PMC3694694 DOI: 10.1105/tpc.113.110452] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Revised: 04/17/2013] [Accepted: 04/26/2013] [Indexed: 05/19/2023]
Abstract
CRK5 is a member of the Arabidopsis thaliana Ca(2+)/calmodulin-dependent kinase-related kinase family. Here, we show that inactivation of CRK5 inhibits primary root elongation and delays gravitropic bending of shoots and roots. Reduced activity of the auxin-induced DR5-green fluorescent protein reporter suggests that auxin is depleted from crk5 root tips. However, no tip collapse is observed and the transcription of genes for auxin biosynthesis, AUXIN TRANSPORTER/AUXIN TRANSPORTER-LIKE PROTEIN (AUX/LAX) auxin influx, and PIN-FORMED (PIN) efflux carriers is unaffected by the crk5 mutation. Whereas AUX1, PIN1, PIN3, PIN4, and PIN7 display normal localization, PIN2 is depleted from apical membranes of epidermal cells and shows basal to apical relocalization in the cortex of the crk5 root transition zone. This, together with an increase in the number of crk5 lateral root primordia, suggests facilitated auxin efflux through the cortex toward the elongation zone. CRK5 is a plasma membrane-associated kinase that forms U-shaped patterns facing outer lateral walls of epidermis and cortex cells. Brefeldin inhibition of exocytosis stimulates CRK5 internalization into brefeldin bodies. CRK5 phosphorylates the hydrophilic loop of PIN2 in vitro, and PIN2 shows accelerated accumulation in brefeldin bodies in the crk5 mutant. Delayed gravitropic response of the crk5 mutant thus likely reflects defective phosphorylation of PIN2 and deceleration of its brefeldin-sensitive membrane recycling.
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Affiliation(s)
- Gábor Rigó
- Institute of Plant Biology, Biological Research Center, H-6726 Szeged, Hungary
| | - Ferhan Ayaydin
- Institute of Plant Biology, Biological Research Center, H-6726 Szeged, Hungary
| | - Olaf Tietz
- Institute of Biology II/Molecular Plant Physiology, Faculty of Biology, Albert-Ludwigs-University of Freiburg, D-79104 Freiburg, Germany
| | - Laura Zsigmond
- Institute of Plant Biology, Biological Research Center, H-6726 Szeged, Hungary
- Department of Plant Biology, University of Szeged, H-6726 Szeged, Hungary
| | - Hajnalka Kovács
- Institute of Plant Biology, Biological Research Center, H-6726 Szeged, Hungary
| | - Anikó Páy
- Institute of Plant Biology, Biological Research Center, H-6726 Szeged, Hungary
| | - Klaus Salchert
- BASF Plant Science, DNA Landmarks, Quebec J3B 6X3, Canada
| | - Zsuzsanna Darula
- Laboratory of Proteomics Research, Biological Research Center of the Hungarian Academy of Sciences, H-6726 Szeged, Hungary
| | - Katalin F. Medzihradszky
- Laboratory of Proteomics Research, Biological Research Center of the Hungarian Academy of Sciences, H-6726 Szeged, Hungary
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94158
| | - László Szabados
- Institute of Plant Biology, Biological Research Center, H-6726 Szeged, Hungary
| | - Klaus Palme
- Institute of Biology II/Molecular Plant Physiology, Faculty of Biology, Albert-Ludwigs-University of Freiburg, D-79104 Freiburg, Germany
| | - Csaba Koncz
- Institute of Plant Biology, Biological Research Center, H-6726 Szeged, Hungary
- Max-Planck Institute für Züchtungschforshung, D-50829 Cologne, Germany
- Address correspondence to
| | - Ágnes Cséplő
- Institute of Plant Biology, Biological Research Center, H-6726 Szeged, Hungary
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50
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Chalupowicz L, Weinthal D, Gaba V, Sessa G, Barash I, Manulis-Sasson S. Polar auxin transport is essential for gall formation by Pantoea agglomerans on Gypsophila. MOLECULAR PLANT PATHOLOGY 2013; 14:185-90. [PMID: 23083316 PMCID: PMC6638636 DOI: 10.1111/j.1364-3703.2012.00839.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The virulence of the bacterium Pantoea agglomerans pv. gypsophilae (Pag) on Gypsophila paniculata depends on a type III secretion system (T3SS) and its effectors. The hypothesis that plant-derived indole-3-acetic acid (IAA) plays a major role in gall formation was examined by disrupting basipetal polar auxin transport with the specific inhibitors 2,3,5-triiodobenzoic acid (TIBA) and N-1-naphthylphthalamic acid (NPA). On inoculation with Pag, galls developed in gypsophila stems above but not below lanolin rings containing TIBA or NPA, whereas, in controls, galls developed above and below the rings. In contrast, TIBA and NPA could not inhibit tumour formation in tomato caused by Agrobacterium tumefaciens. The colonization of gypsophila stems by Pag was reduced below, but not above, the lanolin-TIBA ring. Following Pag inoculation and TIBA treatment, the expression of hrpL (a T3SS regulator) and pagR (a quorum-sensing transcriptional regulator) decreased four-fold and that of pthG (a T3SS effector) two-fold after 24 h. Expression of PIN2 (a putative auxin efflux carrier) increased 35-fold, 24 h after Pag inoculation. However, inoculation with a mutant in the T3SS effector pthG reduced the expression of PIN2 by two-fold compared with wild-type infection. The results suggest that pthG might govern the elevation of PIN2 expression during infection, and that polar auxin transport-derived IAA is essential for gall initiation.
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Affiliation(s)
- Laura Chalupowicz
- Department of Plant Pathology and Weed Research, ARO, Volcani Center, Bet Dagan 50250, Israel
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