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D'Incà R, Mattioli R, Tomasella M, Tavazza R, Macone A, Incocciati A, Martignago D, Polticelli F, Fraudentali I, Cona A, Angelini R, Tavazza M, Nardini A, Tavladoraki P. A Solanum lycopersicum polyamine oxidase contributes to the control of plant growth, xylem differentiation, and drought stress tolerance. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024; 119:960-981. [PMID: 38761363 DOI: 10.1111/tpj.16809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 04/26/2024] [Accepted: 05/03/2024] [Indexed: 05/20/2024]
Abstract
Polyamines are involved in several plant physiological processes. In Arabidopsis thaliana, five FAD-dependent polyamine oxidases (AtPAO1 to AtPAO5) contribute to polyamine homeostasis. AtPAO5 catalyzes the back-conversion of thermospermine (T-Spm) to spermidine and plays a role in plant development, xylem differentiation, and abiotic stress tolerance. In the present study, to verify whether T-Spm metabolism can be exploited as a new route to improve stress tolerance in crops and to investigate the underlying mechanisms, tomato (Solanum lycopersicum) AtPAO5 homologs were identified (SlPAO2, SlPAO3, and SlPAO4) and CRISPR/Cas9-mediated loss-of-function slpao3 mutants were obtained. Morphological, molecular, and physiological analyses showed that slpao3 mutants display increased T-Spm levels and exhibit changes in growth parameters, number and size of xylem elements, and expression levels of auxin- and gibberellin-related genes compared to wild-type plants. The slpao3 mutants are also characterized by improved tolerance to drought stress, which can be attributed to a diminished xylem hydraulic conductivity that limits water loss, as well as to a reduced vulnerability to embolism. Altogether, this study evidences conservation, though with some significant variations, of the T-Spm-mediated regulatory mechanisms controlling plant growth and differentiation across different plant species and highlights the T-Spm role in improving stress tolerance while not constraining growth.
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Affiliation(s)
- Riccardo D'Incà
- Department of Science, University Roma Tre, 00146, Rome, Italy
| | | | - Martina Tomasella
- Dipartimento di Scienze della Vita, Università di Trieste, Trieste, Italy
| | - Raffaela Tavazza
- Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), BIOAG-BIOTEC C.R. Casaccia, Rome, Italy
| | - Alberto Macone
- Department of Biochemical Sciences 'A. Rossi Fanelli', Sapienza University of Rome, Rome, Italy
| | - Alessio Incocciati
- Department of Biochemical Sciences 'A. Rossi Fanelli', Sapienza University of Rome, Rome, Italy
| | | | - Fabio Polticelli
- Department of Science, University Roma Tre, 00146, Rome, Italy
- National Institute of Nuclear Physics, Roma Tre Section, 00146, Rome, Italy
| | | | - Alessandra Cona
- Department of Science, University Roma Tre, 00146, Rome, Italy
- Istituto Nazionale Biostrutture e Biosistemi (INBB), Rome, Italy
| | - Riccardo Angelini
- Department of Science, University Roma Tre, 00146, Rome, Italy
- Istituto Nazionale Biostrutture e Biosistemi (INBB), Rome, Italy
- NBFC, National Biodiversity Future Center, Palermo, Italy
| | - Mario Tavazza
- Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), BIOAG-BIOTEC C.R. Casaccia, Rome, Italy
| | - Andrea Nardini
- Dipartimento di Scienze della Vita, Università di Trieste, Trieste, Italy
| | - Paraskevi Tavladoraki
- Department of Science, University Roma Tre, 00146, Rome, Italy
- Istituto Nazionale Biostrutture e Biosistemi (INBB), Rome, Italy
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Zang Y, Pei Y, Cong X, Ran F, Liu L, Wang C, Wang D, Min Y. Single-cell RNA-sequencing profiles reveal the developmental landscape of the Manihot esculenta Crantz leaves. PLANT PHYSIOLOGY 2023; 194:456-474. [PMID: 37706525 PMCID: PMC10756766 DOI: 10.1093/plphys/kiad500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 06/26/2023] [Accepted: 07/05/2023] [Indexed: 09/15/2023]
Abstract
Cassava (Manihot esculenta Crantz) is an important crop with a high photosynthetic rate and high yield. It is classified as a C3-C4 plant based on its photosynthetic and structural characteristics. To investigate the structural and photosynthetic characteristics of cassava leaves at the cellular level, we created a single-cell transcriptome atlas of cassava leaves. A total of 11,177 high-quality leaf cells were divided into 15 cell clusters. Based on leaf cell marker genes, we identified 3 major tissues of cassava leaves, which were mesophyll, epidermis, and vascular tissue, and analyzed their distinctive properties and metabolic activity. To supplement the genes for identifying the types of leaf cells, we screened 120 candidate marker genes. We constructed a leaf cell development trajectory map and discovered 6 genes related to cell differentiation fate. The structural and photosynthetic properties of cassava leaves analyzed at the single cellular level provide a theoretical foundation for further enhancing cassava yield and nutrition.
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Affiliation(s)
- Yuwei Zang
- Department of Biotechnology, School of Life Sciences, Hainan University, Haikou, Hainan 570228, China
| | - Yechun Pei
- Department of Biotechnology, School of Life Sciences, Hainan University, Haikou, Hainan 570228, China
- Laboratory of Biopharmaceuticals and Molecular Pharmacology, School of Pharmaceutical Sciences, Hainan University, Haikou, Hainan 570228, China
| | - Xinli Cong
- Department of Biotechnology, School of Life Sciences, Hainan University, Haikou, Hainan 570228, China
- Laboratory of Biopharmaceuticals and Molecular Pharmacology, School of Pharmaceutical Sciences, Hainan University, Haikou, Hainan 570228, China
| | - Fangfang Ran
- Department of Biotechnology, School of Life Sciences, Hainan University, Haikou, Hainan 570228, China
| | - Liangwang Liu
- Department of Biotechnology, School of Life Sciences, Hainan University, Haikou, Hainan 570228, China
| | - Changyi Wang
- Department of Biotechnology, School of Life Sciences, Hainan University, Haikou, Hainan 570228, China
| | - Dayong Wang
- Laboratory of Biopharmaceuticals and Molecular Pharmacology, School of Pharmaceutical Sciences, Hainan University, Haikou, Hainan 570228, China
| | - Yi Min
- Department of Biotechnology, School of Life Sciences, Hainan University, Haikou, Hainan 570228, China
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Du J, Wang Y, Chen W, Xu M, Zhou R, Shou H, Chen J. High-resolution anatomical and spatial transcriptome analyses reveal two types of meristematic cell pools within the secondary vascular tissue of poplar stem. MOLECULAR PLANT 2023; 16:809-828. [PMID: 36895162 DOI: 10.1016/j.molp.2023.03.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Revised: 02/12/2023] [Accepted: 03/06/2023] [Indexed: 05/04/2023]
Abstract
The secondary vascular tissue emanating from meristems is central to understanding how vascular plants such as forest trees evolve, grow, and regulate secondary radial growth. However, the overall molecular characterization of meristem origins and developmental trajectories from primary to secondary vascular tissues in woody tree stems is technically challenging. In this study, we combined high-resolution anatomic analysis with a spatial transcriptome (ST) technique to define features of meristematic cells in a developmental gradient from primary to secondary vascular tissues in poplar stems. The tissue-specific gene expression of meristems and derived vascular tissue types were accordingly mapped to specific anatomical domains. Pseudotime analyses were used to track the origins and changes of meristems throughout the development from primary to secondary vascular tissues. Surprisingly, two types of meristematic-like cell pools within secondary vascular tissues were inferred based on high-resolution microscopy combined with ST, and the results were confirmed by in situ hybridization of, transgenic trees, and single-cell sequencing. The rectangle shape procambium-like (PCL) cells develop from procambium meristematic cells and are located within the phloem domain to produce phloem cells, whereas fusiform shape cambium zone (CZ) meristematic cells develop from fusiform metacambium meristematic cells and are located inside the CZ to produce xylem cells. The gene expression atlas and transcriptional networks spanning the primary transition to secondary vascular tissues generated in this work provide new resources for studying the regulation of meristem activities and the evolution of vascular plants. A web server (https://pgx.zju.edu.cn/stRNAPal/) was also established to facilitate the use of ST RNA-seq data.
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Affiliation(s)
- Juan Du
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, 866 Yu Hangtang Road, Hangzhou, Zhejiang 310058, China.
| | - Yichen Wang
- Hangzhou Botanical Garden, Taoyuanling Road, Hangzhou, Zhejiang 310013, China
| | - Wenfan Chen
- Institute of Quantitative Biology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Mingling Xu
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, 866 Yu Hangtang Road, Hangzhou, Zhejiang 310058, China
| | - Ruhong Zhou
- MOE Key Laboratory of Biosystems Homeostasis & Protection, College of Life Sciences, Zhejiang University, 866 Yu Hangtang Road, Hangzhou, Zhejiang 310058, China; Institute of Quantitative Biology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Huixia Shou
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, 866 Yu Hangtang Road, Hangzhou, Zhejiang 310058, China
| | - Jun Chen
- MOE Key Laboratory of Biosystems Homeostasis & Protection, College of Life Sciences, Zhejiang University, 866 Yu Hangtang Road, Hangzhou, Zhejiang 310058, China.
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Song J, Wang Y, Pan Y, Pang J, Zhang X, Fan J, Zhang Y. The influence of nitrogen availability on anatomical and physiological responses of Populus alba × P. glandulosa to drought stress. BMC PLANT BIOLOGY 2019; 19:63. [PMID: 30736746 PMCID: PMC6368793 DOI: 10.1186/s12870-019-1667-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 01/31/2019] [Indexed: 05/08/2023]
Abstract
BACKGROUND Drought and nitrogen (N) deficiency are two major limiting factors for forest productivity in many ecosystems. Elucidating the mechanisms underlying the influence of soil N availability on drought responses of tree species is crucial to improve tree growth under drought. RESULTS The root proliferation under drought was enhanced by adequate N application. Vessel frequency in xylem increased upon drought, with more significant increase under adequate N conditions compared with that under low N conditions, possibly leading to increased hydraulic safety. Nitrogen application under drought increased indole acetic acid (IAA), which contributed to the adaptive changes of xylem. Nitrogen application increased leaf abscisic acid (ABA) concentration, therefore regulated stomata adjustment, and promoted intrinsic water use efficiency (WUEi). Moreover, N application promoted antioxidant defense in leaves by showing increased level of free proline and carotenoid, which improved drought tolerance and growth performance of poplars. CONCLUSIONS Anatomical and physiological responses of Populus to drought were suppressed by N deficiency. Adequate N application promoted adaptive changes of root and xylem under drought and increased hydraulic safety. Nitrogen addition under drought also increased leaf ABA level which may regulate stomata adjustment and promote WUEi. Moreover, nitrogen application improved antioxidant defense in leaves with increased levels of antioxidants. These positive regulations improved drought tolerance and growth performance of poplars.
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Affiliation(s)
- Junyu Song
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Forestry, Northwest A&F University, Yangling, 712100 Shaanxi China
| | - Yang Wang
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Forestry, Northwest A&F University, Yangling, 712100 Shaanxi China
| | - Yuehan Pan
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Forestry, Northwest A&F University, Yangling, 712100 Shaanxi China
| | - Jiayin Pang
- The UWA Institute of Agriculture, and the School of Agriculture and Environment, The University of Western Australia, Perth, WA 6001 Australia
| | - Xin Zhang
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Forestry, Northwest A&F University, Yangling, 712100 Shaanxi China
| | - Junfeng Fan
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Forestry, Northwest A&F University, Yangling, 712100 Shaanxi China
| | - Yi Zhang
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Forestry, Northwest A&F University, Yangling, 712100 Shaanxi China
- School of Biological Science, The University of Western Australia, Perth, WA 6001 Australia
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Hellmann E, Ko D, Ruonala R, Helariutta Y. Plant Vascular Tissues-Connecting Tissue Comes in All Shapes. PLANTS (BASEL, SWITZERLAND) 2018; 7:E109. [PMID: 30551673 PMCID: PMC6313914 DOI: 10.3390/plants7040109] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 11/23/2018] [Accepted: 12/07/2018] [Indexed: 12/23/2022]
Abstract
For centuries, humans have grown and used structures based on vascular tissues in plants. One could imagine that life would have developed differently without wood as a resource for building material, paper, heating energy, or fuel and without edible tubers as a food source. In this review, we will summarise the status of research on Arabidopsis thaliana vascular development and subsequently focus on how this knowledge has been applied and expanded in research on the wood of trees and storage organs of crop plants. We will conclude with an outlook on interesting open questions and exciting new research opportunities in this growing and important field.
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Affiliation(s)
- Eva Hellmann
- The Sainsbury Laboratory, University of Cambridge, Cambridge CB2 1LR, UK.
| | - Donghwi Ko
- The Sainsbury Laboratory, University of Cambridge, Cambridge CB2 1LR, UK.
| | - Raili Ruonala
- The Sainsbury Laboratory, University of Cambridge, Cambridge CB2 1LR, UK.
- Institute of Biotechnology, Department of Biological and Environmental Sciences, University of Helsinki, FI-00014 Helsinki, Finland.
| | - Ykä Helariutta
- The Sainsbury Laboratory, University of Cambridge, Cambridge CB2 1LR, UK.
- Institute of Biotechnology, Department of Biological and Environmental Sciences, University of Helsinki, FI-00014 Helsinki, Finland.
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Abstract
Themospermine is a structural isomer of spermine and is present in some bacteria and most of plants. An Arabidopsis mutant, acaulis5 (acl5), that is defective in the biosynthesis of thermospermine displays excessive proliferation of xylem vessels with dwarfed growth. Recent studies using acl5 and its suppressor mutants that recover the growth without thermospermine have revealed that thermospermine plays a key role in the negative control of the proliferation of xylem vessels through enhancing translation of specific mRNAs that contain a conserved upstream open-reading-frame (uORF) in the 5' leader region.
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Affiliation(s)
- Taku Takahashi
- Division of Earth, Life, and Molecular Sciences, Graduate School of Natural Science and Technology, Okayama University, Tsushimanaka 3-1-1, kita-ku, 700-8530, Okayama, Japan.
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Patel J, Ariyaratne M, Ahmed S, Ge L, Phuntumart V, Kalinoski A, Morris PF. Dual functioning of plant arginases provides a third route for putrescine synthesis. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2017; 262:62-73. [PMID: 28716421 DOI: 10.1016/j.plantsci.2017.05.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 05/04/2017] [Accepted: 05/25/2017] [Indexed: 05/19/2023]
Abstract
Two biosynthetic routes are known for putrescine, an essential plant metabolite. Ornithine decarboxylase (ODC) converts ornithine directly to putrescine, while a second route for putrescine biosynthesis utilizes arginine decarboxylase (ADC) to convert arginine to agmatine, and two additional enzymes, agmatine iminohydrolase (AIH) and N-carbamoyl putrescine aminohydrolase (NLP1) to complete this pathway. Here we show that plants can use ADC and arginase/agmatinase (ARGAH) as a third route for putrescine synthesis. Transformation of Arabidopsis thaliana ADC2, and any of the arginases from A. thaliana (ARGAH1, or ARGHA2) or the soybean gene Glyma.03g028000 (GmARGAH) into a yeast strain deficient in ODC, fully complemented the mutant phenotype. In vitro assays using purified recombinant enzymes of AtADC1 and AtARGAH2 were used to show that these enzymes can function in concert to convert arginine to agmatine and putrescine. Transient expression analysis of the soybean genes (Glyma.06g007500, ADC; Glyma.03g028000 GmARGAH) and the A. thaliana ADC2 and ARGAH genes in leaves of Nicotiana benthamiana, showed that these proteins are localized to the chloroplast. Experimental support for this pathway also comes from the fact that expression of AtARGAH, but not AtAIH or AtNLP1, is co-regulated with AtADC2 in response to drought, oxidative stress, wounding, and methyl jasmonate treatments. Based on the high affinity of ARGAH2 for agmatine, its co-localization with ADC2, and typically low arginine levels in many plant tissues, we propose that these two enzymes can be major contributors to putrescine synthesis in many A. thaliana stress responses.
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Affiliation(s)
- Jigar Patel
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403, United States
| | - Menaka Ariyaratne
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403, United States
| | - Sheaza Ahmed
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403, United States
| | - Lingxiao Ge
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403, United States
| | - Vipaporn Phuntumart
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403, United States
| | - Andrea Kalinoski
- Department of Surgery, University of Toledo, 3000 Arlington Ave, Toledo, OH 43614, United States
| | - Paul F Morris
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403, United States.
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Alabdallah O, Ahou A, Mancuso N, Pompili V, Macone A, Pashkoulov D, Stano P, Cona A, Angelini R, Tavladoraki P. The Arabidopsis polyamine oxidase/dehydrogenase 5 interferes with cytokinin and auxin signaling pathways to control xylem differentiation. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:997-1012. [PMID: 28199662 DOI: 10.1093/jxb/erw510] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In plants, the polyamines putrescine, spermidine, spermine (Spm), and thermospermine (Therm-Spm) participate in several physiological processes. In particular, Therm-Spm is involved in the control of xylem differentiation, having an auxin antagonizing effect. Polyamine oxidases (PAOs) are FAD-dependent enzymes involved in polyamine catabolism. In Arabidopsis, five PAOs are present, among which AtPAO5 catalyzes the back-conversion of Spm, Therm-Spm, and N1-acetyl-Spm to spermidine. In the present study, it is shown that two loss-of-function atpao5 mutants and a 35S::AtPAO5 Arabidopsis transgenic line present phenotypical differences from the wild-type plants with regard to stem and root elongation, differences that are accompanied by changes in polyamine levels and the number of xylem vessels. It is additionally shown that cytokinin treatment, which up-regulates AtPAO5 expression in roots, differentially affects protoxylem differentiation in 35S::AtPAO5, atpao5, and wild-type roots. Together with these findings, Therm-Spm biosynthetic genes, as well as auxin-, xylem-, and cytokinin-related genes (such as ACL5, SAMDC4, PIN1, PIN6, VND6, VND7, ATHB8, PHB, CNA, PXY, XTH3, XCP1, and AHP6) are shown to be differentially expressed in the various genotypes. These data suggest that AtPAO5, being involved in the control of Therm-Spm homeostasis, participates in the tightly controlled interplay between auxin and cytokinins that is necessary for proper xylem differentiation.
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Affiliation(s)
| | - Abdellah Ahou
- Department of Sciences, University 'ROMA TRE', Rome, Italy
| | | | | | - Alberto Macone
- Department of Biochemical Sciences 'A. Rossi Fanelli', University of Rome 'La Sapienza', Rome, Italy
| | - Dimitre Pashkoulov
- Società Agricola Floramiata Servizi srl, 53025 Piancastagnaio, Siena, Italy
| | - Pasquale Stano
- Department of Sciences, University 'ROMA TRE', Rome, Italy
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Chemical control of xylem differentiation by thermospermine, xylemin, and auxin. Sci Rep 2016; 6:21487. [PMID: 26879262 PMCID: PMC4754900 DOI: 10.1038/srep21487] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 01/25/2016] [Indexed: 12/14/2022] Open
Abstract
The xylem conducts water and minerals from the root to the shoot and provides mechanical strength to the plant body. The vascular precursor cells of the procambium differentiate to form continuous vascular strands, from which xylem and phloem cells are generated in the proper spatiotemporal pattern. Procambium formation and xylem differentiation are directed by auxin. In angiosperms, thermospermine, a structural isomer of spermine, suppresses xylem differentiation by limiting auxin signalling. However, the process of auxin-inducible xylem differentiation has not been fully elucidated and remains difficult to manipulate. Here, we found that an antagonist of spermidine can act as an inhibitor of thermospermine biosynthesis and results in excessive xylem differentiation, which is a phenocopy of a thermospermine-deficient mutant acaulis5 in Arabidopsis thaliana. We named this compound xylemin owing to its xylem-inducing effect. Application of a combination of xylemin and thermospermine to wild-type seedlings negates the effect of xylemin, whereas co-treatment with xylemin and a synthetic proauxin, which undergoes hydrolysis to release active auxin, has a synergistic inductive effect on xylem differentiation. Thus, xylemin may serve as a useful transformative chemical tool not only for the study of thermospermine function in various plant species but also for the control of xylem induction and woody biomass production.
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Fujita M, Shinozaki K. Identification of polyamine transporters in plants: paraquat transport provides crucial clues. PLANT & CELL PHYSIOLOGY 2014; 55:855-61. [PMID: 24590488 DOI: 10.1093/pcp/pcu032] [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] [Indexed: 05/21/2023]
Abstract
Polyamine (PA) transport as well as PA biosynthesis, degradation and conjugation plays a vital role in the regulation of intracellular PA levels, which are essential for cell growth. Generally, PA uptake activity is elevated in rapidly proliferating cells. Previous studies showed that PA uptake in plant cells occurred via energy-dependent, protein-mediated transport systems. Numerous lines of evidence suggest that paraquat (PQ), one of the most widely used herbicides, is transported by the PA transport system in diverse organisms including plants. The PA/PQ transport interactions are proposed to be due to specific structural similarities between PA and PQ. The understanding of PA transport mechanisms has progressed in parallel with that of PQ transport, but the molecular identity of the plant PA/PQ transporter has remained an enigma. Recently, independent studies identified the L-type amino acid transporter (LAT) family transmembrane proteins as transporters of both PA and PQ. Arabidopsis LAT family proteins showed different subcellular localization properties, which suggested that these transporters were involved in intracellular PA trafficking and PA uptake across the plasma membrane. The identification of plant PA transporters is an important step in understanding the mechanism of PA homeostasis in plant cells. In this review, we highlight recent advances in the study of PA transport systems that are linked to the understanding of PQ translocation.
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Affiliation(s)
- Miki Fujita
- Gene Discovery Research Group, RIKEN Center for Sustainable Resource Science, 3-1-1 Koyadai, Tsukuba, Ibaraki, 305-0074 Japan
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11
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Abstract
Polyamines are ubiquitous and essential components of mammalian cells. They have multiple functions including critical roles in nucleic acid and protein synthesis, gene expression, protein function, protection from oxidative damage, the regulation of ion channels, and maintenance of the structure of cellular macromolecules. It is essential to maintain a correct level of polyamines, and this amount is tightly regulated at the levels of transport, synthesis, and degradation. Catabolic pathways generate reactive aldehydes including acrolein and hydrogen peroxide via a number of oxidases. These metabolites, particularly those from spermine, can cause significant toxicity with damage to proteins, DNA, and other cellular components. Their production can be increased as a result of infection or cell damage that releases free polyamines and activates the oxidative catabolic pathways. Since polyamines also have an important physiological role in protection from oxidative damage, the reduction in polyamine content may exacerbate the toxic potential of these agents. Increases in polyamine catabolism have been implicated in the development of diseases including stroke, other neurological diseases, renal failure, liver disease, and cancer. These results provide new opportunities for the early diagnosis, prevention, and treatment of disease.
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Affiliation(s)
- Anthony E Pegg
- Department of Cellular and Molecular Physiology, Milton S. Hershey Medical Center, Pennsylvania State University College of Medicine , Hershey, Pennsylvania 17033, United States
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12
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Milhinhos A, Prestele J, Bollhöner B, Matos A, Vera-Sirera F, Rambla JL, Ljung K, Carbonell J, Blázquez MA, Tuominen H, Miguel CM. Thermospermine levels are controlled by an auxin-dependent feedback loop mechanism in Populus xylem. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 75:685-98. [PMID: 23647338 DOI: 10.1111/tpj.12231] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 04/29/2013] [Accepted: 05/01/2013] [Indexed: 05/03/2023]
Abstract
Polyamines are small polycationic amines that are widespread in living organisms. Thermospermine, synthesized by thermospermine synthase ACAULIS5 (ACL5), was recently shown to be an endogenous plant polyamine. Thermospermine is critical for proper vascular development and xylem cell specification, but it is not known how thermospermine homeostasis is controlled in the xylem. We present data in the Populus model system supporting the existence of a negative feedback control of thermospermine levels in stem xylem tissues, the main site of thermospermine biosynthesis. While over-expression of the ACL5 homologue in Populus, POPACAULIS5, resulted in strong up-regulation of ACL5 expression and thermospermine accumulation in leaves, the corresponding levels in the secondary xylem tissues of the stem were similar or lower than those in the wild-type. POPACAULIS5 over-expression had a negative effect on accumulation of indole-3-acetic acid, while exogenous auxin had a positive effect on POPACAULIS5 expression, thus promoting thermospermine accumulation. Further, over-expression of POPACAULIS5 negatively affected expression of the class III homeodomain leucine zipper (HD-Zip III) transcription factor gene PttHB8, a homologue of AtHB8, while up-regulation of PttHB8 positively affected POPACAULIS5 expression. These results indicate that excessive accumulation of thermospermine is prevented by a negative feedback control of POPACAULIS5 transcript levels through suppression of indole-3-acetic acid levels, and that PttHB8 is involved in the control of POPACAULIS5 expression. We propose that this negative feedback loop functions to maintain steady-state levels of thermospermine, which is required for proper xylem development, and that it is dependent on the presence of high concentrations of endogenous indole-3-acetic acid, such as those present in the secondary xylem tissues.
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Affiliation(s)
- Ana Milhinhos
- Instituto de Biologia Experimental e Tecnológica, Apartado 12, 2781-901, Oeiras, Portugal
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