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Lutter F, Brenner W, Krajinski-Barth F, Safavi-Rizi V. Nitric oxide and cytokinin cross-talk and their role in plant hypoxia response. PLANT SIGNALING & BEHAVIOR 2024; 19:2329841. [PMID: 38521996 PMCID: PMC10962617 DOI: 10.1080/15592324.2024.2329841] [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: 12/15/2023] [Accepted: 03/07/2024] [Indexed: 03/25/2024]
Abstract
Nitric oxide (NO) and cytokinins (CKs) are known for their crucial contributions to plant development, growth, senescence, and stress response. Despite the importance of both signals in stress responses, their interaction remains largely unexplored. The interplay between NO and CKs emerges as particularly significant not only regarding plant growth and development but also in addressing plant stress response, particularly in the context of extreme weather events leading to yield loss. In this review, we summarize NO and CKs metabolism and signaling. Additionally, we emphasize the crosstalk between NO and CKs, underscoring its potential impact on stress response, with a focus on hypoxia tolerance. Finally, we address the most urgent questions that demand answers and offer recommendations for future research endeavors.
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Affiliation(s)
- Felix Lutter
- Institute of Biology, Department of General and Applied Botany, University of Leipzig, Leipzig, Germany
| | - Wolfram Brenner
- Institute of Biology, Department of General and Applied Botany, University of Leipzig, Leipzig, Germany
| | - Franziska Krajinski-Barth
- Institute of Biology, Department of General and Applied Botany, University of Leipzig, Leipzig, Germany
| | - Vajiheh Safavi-Rizi
- Institute of Biology, Department of General and Applied Botany, University of Leipzig, Leipzig, Germany
- Institute of Biology, Department of Plant physiology, University of Leipzig, Leipzig, Germany
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2
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Mandal S, Ghorai M, Anand U, Samanta D, Kant N, Mishra T, Rahman MH, Jha NK, Jha SK, Lal MK, Tiwari RK, Kumar M, Radha, Prasanth DA, Mane AB, Gopalakrishnan AV, Biswas P, Proćków J, Dey A. Cytokinin and abiotic stress tolerance -What has been accomplished and the way forward? Front Genet 2022; 13:943025. [PMID: 36017502 PMCID: PMC9395584 DOI: 10.3389/fgene.2022.943025] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 06/30/2022] [Indexed: 11/27/2022] Open
Abstract
More than a half-century has passed since it was discovered that phytohormone cytokinin (CK) is essential to drive cytokinesis and proliferation in plant tissue culture. Thereafter, cytokinin has emerged as the primary regulator of the plant cell cycle and numerous developmental processes. Lately, a growing body of evidence suggests that cytokinin has a role in mitigating both abiotic and biotic stress. Cytokinin is essential to defend plants against excessive light exposure and a unique kind of abiotic stress generated by an altered photoperiod. Secondly, cytokinin also exhibits multi-stress resilience under changing environments. Furthermore, cytokinin homeostasis is also affected by several forms of stress. Therefore, the diverse roles of cytokinin in reaction to stress, as well as its interactions with other hormones, are discussed in detail. When it comes to agriculture, understanding the functioning processes of cytokinins under changing environmental conditions can assist in utilizing the phytohormone, to increase productivity. Through this review, we briefly describe the biological role of cytokinin in enhancing the performance of plants growth under abiotic challenges as well as the probable mechanisms underpinning cytokinin-induced stress tolerance. In addition, the article lays forth a strategy for using biotechnological tools to modify genes in the cytokinin pathway to engineer abiotic stress tolerance in plants. The information presented here will assist in better understanding the function of cytokinin in plants and their effective investigation in the cropping system.
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Affiliation(s)
- Sayanti Mandal
- Institute of Bioinformatics and Biotechnology, Savitribai Phule Pune University, Pune, Maharashtra, India
| | - Mimosa Ghorai
- Department of Life Sciences, Presidency University, Kolkata, West Bengal, India
| | - Uttpal Anand
- CytoGene Research & Development LLP, Barabanki, Uttar Pradesh, India
| | - Dipu Samanta
- Department of Botany, Dr. Kanailal Bhattacharyya College, Howrah, West Bengal, India
| | - Nishi Kant
- School of Health and Allied Science, ARKA Jain University, Jamshedpur, Jharkhand, India
| | - Tulika Mishra
- Department of Botany, Deen Dayal Upadhyay Gorakhpur University, Gorakhpur, Uttar Pradesh, India
| | - Md. Habibur Rahman
- Department of Global Medical Science, Wonju College of Medicine, Yonsei University, Wonju, Gangwon-do, South Korea
| | - Niraj Kumar Jha
- Department of Biotechnology, School of Engineering and Technology, Sharda University, Greater Noida, Uttar Pradesh, India
- Department of Biotechnology Engineering and Food Technology, Chandigarh University, Mohali, India
- Department of Biotechnology, School of Applied and Life Sciences (SALS), Uttaranchal University, Dehradun, India
| | - Saurabh Kumar Jha
- Department of Biotechnology, School of Engineering and Technology, Sharda University, Greater Noida, Uttar Pradesh, India
- Department of Biotechnology Engineering and Food Technology, Chandigarh University, Mohali, India
- Department of Biotechnology, School of Applied and Life Sciences (SALS), Uttaranchal University, Dehradun, India
| | - Milan Kumar Lal
- Division of Crop Physiology, Biochemistry and Post Harvest Technology, ICAR-Central Potato Research Institute, Shimla, Himachal Pradesh, India
| | - Rahul Kumar Tiwari
- Division of Crop Physiology, Biochemistry and Post Harvest Technology, ICAR-Central Potato Research Institute, Shimla, Himachal Pradesh, India
| | - Manoj Kumar
- Chemical and Biochemical Processing Division, ICAR-Central Institute for Research on Cotton Technology, Mumbai, Maharashtra, India
| | - Radha
- School of Biological and Environmental Sciences, Shoolini University of Biotechnology and Management Sciences, Solan, Himachal Pradesh, India
| | | | - Abhijit Bhagwan Mane
- Department of Zoology, Dr. Patangrao Kadam Mahavidhyalaya (affiliated to Shivaji University Kolhapur), Ramanandnagar (Burli), Sangli, Maharashtra, India
| | - Abilash Valsala Gopalakrishnan
- Department of Biomedical Sciences, School of Biosciences and Technology, Vellore Institute of Technology (VIT), Vellore, Tamil Nadu, India
| | - Protha Biswas
- Department of Life Sciences, Presidency University, Kolkata, West Bengal, India
| | - Jarosław Proćków
- Department of Plant Biology, Institute of Environmental Biology, Wrocław University of Environmental and Life Sciences, Wrocław, Poland
| | - Abhijit Dey
- Department of Life Sciences, Presidency University, Kolkata, West Bengal, India
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Tregear JW, Richaud F, Collin M, Esbelin J, Parrinello H, Cochard B, Nodichao L, Morcillo F, Adam H, Jouannic S. Micro-RNA-Regulated SQUAMOSA-PROMOTER BINDING PROTEIN-LIKE (SPL) Gene Expression and Cytokinin Accumulation Distinguish Early-Developing Male and Female Inflorescences in Oil Palm (Elaeis guineensis). PLANTS 2022; 11:plants11050685. [PMID: 35270155 PMCID: PMC8912876 DOI: 10.3390/plants11050685] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 02/25/2022] [Accepted: 02/28/2022] [Indexed: 11/16/2022]
Abstract
Sexual differentiation of inflorescences and flowers is important for reproduction and affects crop plant productivity. We report here on a molecular study of the process of sexual differentiation in the immature inflorescence of oil palm (Elaeis guineensis). This species is monoecious and exhibits gender diphasy, producing male and female inflorescences separately on the same plant in alternation. Three main approaches were used: small RNA-seq to characterise and study the expression of miRNA genes; RNA-seq to monitor mRNA accumulation patterns; hormone quantification to assess the role of cytokinins and auxins in inflorescence differentiation. Our study allowed the characterisation of 30 previously unreported palm MIRNA genes. In differential gene and miRNA expression studies, we identified a number of key developmental genes and miRNA-mRNA target modules previously described in relation to their developmental regulatory role in the cereal panicle, notably the miR156/529/535-SQUAMOSA PROMOTER-BINDING PROTEIN-LIKE (SPL) gene regulatory module. Gene enrichment analysis highlighted the importance of hormone-related genes, and this observation was corroborated by the detection of much higher levels of cytokinins in the female inflorescence. Our data illustrate the importance of branching regulation within the developmental window studied, during which the female inflorescence, unlike its male counterpart, produces flower clusters on new successive axes by sympodial growth.
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Affiliation(s)
- James W. Tregear
- DIADE, University of Montpellier, CIRAD, IRD, 34394 Montpellier, France; (M.C.); (J.E.); (F.M.); (H.A.); (S.J.)
- Correspondence:
| | - Frédérique Richaud
- CIRAD, UMR AGAP, 34398 Montpellier, France;
- AGAP, University of Montpellier, CIRAD, INRAE, Institut Agro, 34398 Montpellier, France
| | - Myriam Collin
- DIADE, University of Montpellier, CIRAD, IRD, 34394 Montpellier, France; (M.C.); (J.E.); (F.M.); (H.A.); (S.J.)
| | - Jennifer Esbelin
- DIADE, University of Montpellier, CIRAD, IRD, 34394 Montpellier, France; (M.C.); (J.E.); (F.M.); (H.A.); (S.J.)
| | - Hugues Parrinello
- MGX-Montpellier GenomiX, University of Montpellier, CNRS, INSERM, 34094 Montpellier, France;
| | | | | | - Fabienne Morcillo
- DIADE, University of Montpellier, CIRAD, IRD, 34394 Montpellier, France; (M.C.); (J.E.); (F.M.); (H.A.); (S.J.)
- CIRAD, UMR DIADE, 34394 Montpellier, France
| | - Hélène Adam
- DIADE, University of Montpellier, CIRAD, IRD, 34394 Montpellier, France; (M.C.); (J.E.); (F.M.); (H.A.); (S.J.)
| | - Stefan Jouannic
- DIADE, University of Montpellier, CIRAD, IRD, 34394 Montpellier, France; (M.C.); (J.E.); (F.M.); (H.A.); (S.J.)
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Vylíčilová H, Bryksová M, Matušková V, Doležal K, Plíhalová L, Strnad M. Naturally Occurring and Artificial N9-Cytokinin Conjugates: From Synthesis to Biological Activity and Back. Biomolecules 2020; 10:biom10060832. [PMID: 32485963 PMCID: PMC7356397 DOI: 10.3390/biom10060832] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 05/26/2020] [Accepted: 05/26/2020] [Indexed: 01/18/2023] Open
Abstract
Cytokinins and their sugar or non-sugar conjugates are very active growth-promoting factors in plants, although they occur at very low concentrations. These compounds have been identified in numerous plant species. This review predominantly focuses on 9-substituted adenine-based cytokinin conjugates, both artificial and endogenous, sugar and non-sugar, and their roles in plants. Acquired information about their biological activities, interconversions, and metabolism improves understanding of their mechanisms of action and functions in planta. Although a number of 9-substituted cytokinins occur endogenously, many have also been prepared in laboratories to facilitate the clarification of their physiological roles and the determination of their biological properties. Here, we chart advances in knowledge of 9-substituted cytokinin conjugates from their discovery to current understanding and reciprocal interactions between biological properties and associated structural motifs. Current organic chemistry enables preparation of derivatives with better biological properties, such as improved anti-senescence, strong cell division stimulation, shoot forming, or more persistent stress tolerance compared to endogenous or canonical cytokinins. Many artificial cytokinin conjugates stimulate higher mass production than naturally occurring cytokinins, improve rooting, or simply have high stability or bioavailability. Thus, knowledge of the biosynthesis, metabolism, and activity of 9-substituted cytokinins in various plant species extends the scope for exploiting both natural and artificially prepared cytokinins in plant biotechnology, tissue culture, and agriculture.
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Affiliation(s)
- Hana Vylíčilová
- Department of Chemical Biology and Genetics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Šlechtitelů 27, CZ-783 71 Olomouc, Czech Republic; (H.V.); (M.B.); (V.M.); (K.D.)
| | - Magdaléna Bryksová
- Department of Chemical Biology and Genetics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Šlechtitelů 27, CZ-783 71 Olomouc, Czech Republic; (H.V.); (M.B.); (V.M.); (K.D.)
| | - Vlasta Matušková
- Department of Chemical Biology and Genetics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Šlechtitelů 27, CZ-783 71 Olomouc, Czech Republic; (H.V.); (M.B.); (V.M.); (K.D.)
| | - Karel Doležal
- Department of Chemical Biology and Genetics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Šlechtitelů 27, CZ-783 71 Olomouc, Czech Republic; (H.V.); (M.B.); (V.M.); (K.D.)
- Laboratory of Growth Regulators, Palacký University & Institute of Experimental Botany ASCR, Šlechtitelů 27, CZ-783 71 Olomouc, Czech Republic;
| | - Lucie Plíhalová
- Department of Chemical Biology and Genetics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Šlechtitelů 27, CZ-783 71 Olomouc, Czech Republic; (H.V.); (M.B.); (V.M.); (K.D.)
- Laboratory of Growth Regulators, Palacký University & Institute of Experimental Botany ASCR, Šlechtitelů 27, CZ-783 71 Olomouc, Czech Republic;
- Correspondence:
| | - Miroslav Strnad
- Laboratory of Growth Regulators, Palacký University & Institute of Experimental Botany ASCR, Šlechtitelů 27, CZ-783 71 Olomouc, Czech Republic;
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Sun L, Zhang Q, Wu J, Zhang L, Jiao X, Zhang S, Zhang Z, Sun D, Lu T, Sun Y. Two rice authentic histidine phosphotransfer proteins, OsAHP1 and OsAHP2, mediate cytokinin signaling and stress responses in rice. PLANT PHYSIOLOGY 2014; 165:335-45. [PMID: 24578505 PMCID: PMC4012592 DOI: 10.1104/pp.113.232629] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Cytokinin plays an important role in plant development and stress tolerance. Studies of Arabidopsis (Arabidopsis thaliana) have demonstrated that cytokinin acts through a two-component system that includes a histidine (His) kinase, a His phosphotransfer protein (HP), and a response regulator. Phylogenetic analyses have revealed the conservation of His kinases but lineage-specific expansion of HPs and response regulators in rice (Oryza sativa). However, whether the functions of rice HPs have diverged remains unknown. In this study, two rice authentic HPs (OsAHP1 and OsAHP2) were knocked down simultaneously via RNA interference (RNAi), and the transgenic OsAHP-RNAi plants exhibited phenotypes expected for a deficiency in cytokinin signaling, including dwarfism with reduced internode lengths, enhanced lateral root growth, early leaf senescence, and reduced tiller numbers and fertility under natural conditions. The OsAHP-RNAi seedlings were also hyposensitive to exogenous cytokinin. Furthermore, OsAHP-RNAi seedlings were hypersensitive to salt treatment but resistant to osmotic stress relative to wild-type plants. These results indicate that OsAHPs function as positive regulators of the cytokinin signaling pathway and play different roles in salt and drought tolerance in rice.
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Integration of epigenetic and genetic controls of seed size by cytokinin in Arabidopsis. Proc Natl Acad Sci U S A 2013; 110:15479-84. [PMID: 24003120 DOI: 10.1073/pnas.1305175110] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The development of seeds in flowering plants is placed under complex interactions between maternal tissues, the embryo, and the endosperm. The endosperm plays a major role in the regulation of seed size. In Arabidopsis thaliana, endosperm size depends on the coordination of the genetic pathway HAIKU (IKU) with epigenetic controls comprising genome dosage, DNA methylation, and trimethylated lysine 27 on histone H3 (H3K27me3) deposition. However, the effectors that integrate these pathways have remained unknown. Here, we identify a target of the IKU pathway, the cytokinin oxidase CKX2, that affects cytokinin signaling. CKX2 expression is activated by the IKU transcription factor WRKY10 directly and promotes endosperm growth. CKX2 expression also depends on H3K27me3 deposition, which fluctuates in response to maternal genome dosage imbalance and DNA demethylation of male gametes. Hence, the control of endosperm growth by CKX2 integrates genetic and epigenetic regulations. In angiosperms, cytokinins are highly active in endosperm, and we propose that IKU effectors coordinate environmental and physiological factors, resulting in modulation of seed size.
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7
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Bhargava A, Clabaugh I, To JP, Maxwell BB, Chiang YH, Schaller GE, Loraine A, Kieber JJ. Identification of cytokinin-responsive genes using microarray meta-analysis and RNA-Seq in Arabidopsis. PLANT PHYSIOLOGY 2013; 162:272-94. [PMID: 23524861 PMCID: PMC3641208 DOI: 10.1104/pp.113.217026] [Citation(s) in RCA: 159] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 03/21/2013] [Indexed: 05/17/2023]
Abstract
Cytokinins are N(6)-substituted adenine derivatives that play diverse roles in plant growth and development. We sought to define a robust set of genes regulated by cytokinin as well as to query the response of genes not represented on microarrays. To this end, we performed a meta-analysis of microarray data from a variety of cytokinin-treated samples and used RNA-seq to examine cytokinin-regulated gene expression in Arabidopsis (Arabidopsis thaliana). Microarray meta-analysis using 13 microarray experiments combined with empirically defined filtering criteria identified a set of 226 genes differentially regulated by cytokinin, a subset of which has previously been validated by other methods. RNA-seq validated about 73% of the up-regulated genes identified by this meta-analysis. In silico promoter analysis indicated an overrepresentation of type-B Arabidopsis response regulator binding elements, consistent with the role of type-B Arabidopsis response regulators as primary mediators of cytokinin-responsive gene expression. RNA-seq analysis identified 73 cytokinin-regulated genes that were not represented on the ATH1 microarray. Representative genes were verified using quantitative reverse transcription-polymerase chain reaction and NanoString analysis. Analysis of the genes identified reveals a substantial effect of cytokinin on genes encoding proteins involved in secondary metabolism, particularly those acting in flavonoid and phenylpropanoid biosynthesis, as well as in the regulation of redox state of the cell, particularly a set of glutaredoxin genes. Novel splicing events were found in members of some gene families that are known to play a role in cytokinin signaling or metabolism. The genes identified in this analysis represent a robust set of cytokinin-responsive genes that are useful in the analysis of cytokinin function in plants.
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Garay-Arroyo A, De La Paz Sánchez M, García-Ponce B, Azpeitia E, Álvarez-Buylla ER. Hormone symphony during root growth and development. Dev Dyn 2012; 241:1867-85. [DOI: 10.1002/dvdy.23878] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/17/2012] [Indexed: 01/29/2023] Open
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Arsovski AA, Galstyan A, Guseman JM, Nemhauser JL. Photomorphogenesis. THE ARABIDOPSIS BOOK 2012; 10:e0147. [PMID: 22582028 PMCID: PMC3350170 DOI: 10.1199/tab.0147] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
As photoautotrophs, plants are exquisitely sensitive to their light environment. Light affects many developmental and physiological responses throughout plants' life histories. The focus of this chapter is on light effects during the crucial period of time between seed germination and the development of the first true leaves. During this time, the seedling must determine the appropriate mode of action to best achieve photosynthetic and eventual reproductive success. Light exposure triggers several major developmental and physiological events. These include: growth inhibition and differentiation of the embryonic stem (hypocotyl); maturation of the embryonic leaves (cotyledons); and establishment and activation of the stem cell population in the shoot and root apical meristems. Recent studies have linked a number of photoreceptors, transcription factors, and phytohormones to each of these events.
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Affiliation(s)
- Andrej A. Arsovski
- Department of Biology, University of Washington, Box 351800, Seattle, WA 98195-1800
| | - Anahit Galstyan
- Department of Biology, University of Washington, Box 351800, Seattle, WA 98195-1800
| | - Jessica M. Guseman
- Department of Biology, University of Washington, Box 351800, Seattle, WA 98195-1800
| | - Jennifer L. Nemhauser
- Department of Biology, University of Washington, Box 351800, Seattle, WA 98195-1800
- Address correspondence to
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Cutcliffe JW, Hellmann E, Heyl A, Rashotte AM. CRFs form protein-protein interactions with each other and with members of the cytokinin signalling pathway in Arabidopsis via the CRF domain. JOURNAL OF EXPERIMENTAL BOTANY 2011; 62:4995-5002. [PMID: 21705390 PMCID: PMC3193008 DOI: 10.1093/jxb/err199] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Revised: 05/05/2011] [Accepted: 05/23/2011] [Indexed: 05/19/2023]
Abstract
Cytokinin is a plant hormone essential for growth and development. The elucidation of its signalling pathway as a variant of the bacterial two-component signalling system (TCS) has led to a better understanding of how this hormone is involved in general plant processes. A set of cytokinin-regulated transcription factors known as cytokinin response factors (CRFs) have been described as a potential branch emanating from the TCS, yet little is known about how CRFs actually interact with each other and with members of the TCS pathway. Here the interactions of CRF proteins (CRF1-CRF8) using the yeast two-hybrid system and bimolecular fluorescence complementation in planta assays are described. It was found that CRFs are readily able to form both homo- and heterodimers with each other. The first analysis of CRF versus TCS pathway protein interactions is also provided, which indicates that CRFs (CRF1-CRF8) are able specifically to interact directly with most of the Arabidopsis histidine-phosphotransfer proteins (AHP1-AHP5) further solidifying their link to the cytokinin signalling pathway. In addition, the region of CRF proteins involved in these interactions was mapped and it was determined that the clade-specific CRF domain alone is sufficient for these interactions. This is the first described function for the CRF domain in plants.
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Affiliation(s)
- James W. Cutcliffe
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA
| | - Eva Hellmann
- Institute of Biology/Applied Genetics, Dahlem Centre of Plant Sciences (DCPS), Free University, D-14195 Berlin, Germany
| | - Alexander Heyl
- Institute of Biology/Applied Genetics, Dahlem Centre of Plant Sciences (DCPS), Free University, D-14195 Berlin, Germany
| | - Aaron M. Rashotte
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA
- To whom correspondence should be addressed. E-mail:
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11
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Yevdakova NA, von Schwartzenberg K. Characterisation of a prokaryote-type tRNA-isopentenyltransferase gene from the moss Physcomitrella patens. PLANTA 2007; 226:683-95. [PMID: 17450376 DOI: 10.1007/s00425-007-0516-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2006] [Accepted: 03/16/2007] [Indexed: 05/15/2023]
Abstract
Cytokinins are of critical importance to numerous developmental processes in plants. Two cytokinin biosynthetic pathways have been described; each one uses a different type of isopentenyltransferases (IPTs) as the key enzyme. In the first pathway, adenylate-IPTs (EC 2.5.1.27) prenylate adenylic nucleotides to cytokinin nucleotides, thus catalysing the direct de novo biosynthesis of free cytokinins. In the second pathway, tRNA-IPTs (EC 2.5.1.8) catalyse cytokinin formation by isopentenylation of tRNA, the degradation of which liberates cytokinin nucleotides. Seed plants have been shown to possess both forms of IPTs. Here, we report on the in-silico based identification and on the functional characterisation of an IPT encoding gene (PpIPT1) from the bryophyte Physcomitrella patens. Analysis of the PpIPT1 amino acid sequence revealed high similarities to tRNA-IPTs of other plants. No adenylate-IPT genes were found in the Physcomitrella sequenced transcriptome/genome. PpIPT1 functionally complemented a defective tRNA-IPT gene of Saccharomyces cerevisiae (ScMOD5) in the strain MT-8. Dephosphorylated tRNA hydrolysates from PpIPT1-transformed MT-8 showed cytokinin activity in a moss bioassay and the presence of isopentenyladenosine in HPLC analysis, in contrast to those prepared from untransformed MT-8. A comparison of pro- and eukaryotic homologues revealed two classes of tRNA-IPTs; PpIPT1 belongs to a prokaryotic type with predicted chloroplast targeting. RT-PCR experiments revealed a stronger expression in the cytokinin overproducing mutant oveST25, thus indicating the potential role of PpIPT1 for cytokinin biosynthesis in the evolutionary old land plant Physcomitrella.
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Affiliation(s)
- Natalya A Yevdakova
- Biocenter Klein Flottbek and Botanical Garden, University of Hamburg, Ohnhorst street 18, 22609 Hamburg, Germany
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12
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Dubrovsky JG, Gambetta GA, Hernández-Barrera A, Shishkova S, González I. Lateral root initiation in Arabidopsis: developmental window, spatial patterning, density and predictability. ANNALS OF BOTANY 2006; 97:903-15. [PMID: 16390845 PMCID: PMC2803408 DOI: 10.1093/aob/mcj604] [Citation(s) in RCA: 121] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
BACKGROUND AND AIMS The basic regulatory mechanisms that control lateral root (LR) initiation are still poorly understood. An attempt is made to characterize the pattern and timing of LR initiation, to define a developmental window in which LR initiation takes place and to address the question of whether LR initiation is predictable. METHODS The spatial patterning of LRs and LR primordia (LRPs) on cleared root preparations were characterized. New measures of LR and LRP densities (number of LRs and/or LRPs divided by the length of the root portions where they are present) were introduced and illustrate the shortcomings of the more customarily used measure through a comparative analysis of the mutant aux1-7. The enhancer trap line J0121 was used to monitor LR initiation in time-lapse experiments and a plasmolysis-based method was developed to determine the number of pericycle cells between successive LRPs. KEY RESULTS LRP initiation occurred strictly acropetally and no de novo initiation events were found between already developed LRs or LRPs. However, LRPs did not become LRs in a similar pattern. The longitudinal spacing of lateral organs was variable and the distance between lateral organs was proportional to the number of cells and the time between initiations of successive LRPs. There was a strong tendency towards alternation in LR initiation between the two pericycle cell files adjacent to the protoxylem poles. LR density increased with time due to the emergence of slowly developing LRPs and appears to be unique for individual Arabidopsis accessions. CONCLUSIONS In Arabidopsis there is a narrow developmental window for LR initiation, and no specific cell-count or distance-measuring mechanisms have been found that determine the site of successive initiation events. Nevertheless, the branching density and lateral organ density (density of LRs and LRPs) are accession-specific, and based on the latter density the average distance between successive LRs can be predicted.
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Affiliation(s)
- J G Dubrovsky
- Departamento de Biología Molecular de Plantas, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apartado Postal 510-3, 62250 Cuernavaca, Morelos, Mexico.
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Aloni R, Langhans M, Aloni E, Dreieicher E, Ullrich CI. Root-synthesized cytokinin in Arabidopsis is distributed in the shoot by the transpiration stream. JOURNAL OF EXPERIMENTAL BOTANY 2005; 56:1535-44. [PMID: 15824073 DOI: 10.1093/jxb/eri148] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
To clarify how root-synthesized cytokinins (CKs) are transported to young shoot organs, CK distribution patterns were analysed in free-CK-responsive ARR5::GUS transformants of Arabidopsis thaliana (L.) Heynh. together with free plus bound CKs using specific CK monoclonal antibodies. Plants were subjected to two different growth conditions, completely protected from any air movement, or exposed to gentle wind 3 h before harvesting. In wind-protected plants the strongest ARR5::GUS expression was found in the root cap statocytes, spreading upwards in the vascular cylinder. This pattern in roots was congruent with that found by CK immunolocalization. Shoots of wind-protected plants displayed either no or only low ARR5::GUS expression in the stem vascular bundles, nodal ramifications, and the bases of flower buds; shoot vascular bundles showed patterns of acropetally decreasing staining and the apical parts of buds and leaves were free from ARR5::GUS expression. In wind-exposed plants ARR5::GUS expression was considerably increased in shoots, also in basal-to-apical decreasing gradients. Immunolabelled shoots showed differential staining, with the strongest label in the vascular bundles of stems, leaves, and buds. The fact of the apparent absence of free CK in the buds of wind-protected plants and the typical upward decreasing gradients of free and conjugated CKs suggest that the bulk of the CK is synthesized in the root cap, exported through the xylem and accumulates at sites of highest transpiration where cuticles do not yet exist or do not protect against water loss.
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Affiliation(s)
- Roni Aloni
- Department of Plant Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
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Yonekura-Sakakibara K, Kojima M, Yamaya T, Sakakibara H. Molecular characterization of cytokinin-responsive histidine kinases in maize. Differential ligand preferences and response to cis-zeatin. PLANT PHYSIOLOGY 2004; 134:1654-61. [PMID: 15064375 PMCID: PMC419839 DOI: 10.1104/pp.103.037176] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2003] [Revised: 01/21/2004] [Accepted: 01/21/2004] [Indexed: 05/18/2023]
Abstract
Genes for cytokinin-responsive His-protein kinases (ZmHK1, ZmHK2, and ZmHK3a) were isolated from maize (Zea mays). Heterologous expression of each of the ZmHKs in Escherichia coli having the DeltarcsC and cpslacZ genetic background conferred cytokinin-inducibility of lacZ expression on the bacteria. In the recombinant E. coli system, ZmHK1 and ZmHK3a were more sensitive to free-base cytokinins than to the corresponding nucleosides; isopentenyladenine was most effective for ZmHK1, while ZmHK2 tended to be most sensitive to trans-zeatin and the riboside. In contrast to a known cytokinin receptor of Arabidopsis (AHK4/CRE1/WOL), all ZmHKs responded to cis-zeatin (cZ), which generally is believed to be inactive or only weakly active. In cultured maize cells, expression of ZmRR1, a cytokinin-inducible response regulator, was induced by cZ as well as by trans-zeatin. These results strongly suggest that maize cytokinin receptors differ in ligand preference, and that cZ is an active cytokinin at least in maize.
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Abstract
Cytokinins are plant hormones implicated in diverse and essential processes in plant growth and development, and key genes for the metabolism and actions of cytokinins have recently been identified. Cytokinins are perceived by three histidine kinases--CRE1/WOL/AHK4, AHK2, and AHK3--which initiate intracellular phosphotransfer. The final destination of the transferred phosphoryl groups is response regulators. The type-B Arabidopsis response regulators (ARRs) are DNA-binding transcriptional activators that are required for cytokinin responses. On the other hand, the type-A ARRs act as repressors of cytokinin-activated transcription. How phosphorelay regulate response regulators and how response regulators control downstream events are open questions and discussed in this review.
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Affiliation(s)
- Tatsuo Kakimoto
- Department of Biology, Graduate School of Science, Osaka University, Machikaneyama 1-1, Toyonaka, Osaka 560-0043, Japan.
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