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Chen Y, Aung K, Rolčík J, Walicki K, Friml J, Brandizzi F. Inter-regulation of the unfolded protein response and auxin signaling. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2014; 77:97-107. [PMID: 24180465 PMCID: PMC3981873 DOI: 10.1111/tpj.12373] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Revised: 10/17/2013] [Accepted: 10/21/2013] [Indexed: 05/03/2023]
Abstract
The unfolded protein response (UPR) is a signaling network triggered by overload of protein-folding demand in the endoplasmic reticulum (ER), a condition termed ER stress. The UPR is critical for growth and development; nonetheless, connections between the UPR and other cellular regulatory processes remain largely unknown. Here, we identify a link between the UPR and the phytohormone auxin, a master regulator of plant physiology. We show that ER stress triggers down-regulation of auxin receptors and transporters in Arabidopsis thaliana. We also demonstrate that an Arabidopsis mutant of a conserved ER stress sensor IRE1 exhibits defects in the auxin response and levels. These data not only support that the plant IRE1 is required for auxin homeostasis, they also reveal a species-specific feature of IRE1 in multicellular eukaryotes. Furthermore, by establishing that UPR activation is reduced in mutants of ER-localized auxin transporters, including PIN5, we define a long-neglected biological significance of ER-based auxin regulation. We further examine the functional relationship of IRE1 and PIN5 by showing that an ire1 pin5 triple mutant enhances defects of UPR activation and auxin homeostasis in ire1 or pin5. Our results imply that the plant UPR has evolved a hormone-dependent strategy for coordinating ER function with physiological processes.
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Affiliation(s)
- Yani Chen
- Michigan State University/Department of Energy Plant Research Laboratory and Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA
| | - Kyaw Aung
- Michigan State University/Department of Energy Plant Research Laboratory and Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA
| | - Jakub Rolčík
- Laboratory of Growth Regulators, Faculty of Science, Palacký University and Institute of Experimental Botany AS CR, Šlechtitelů 11, 78371 Olomouc, Czech Republic
| | - Kathryn Walicki
- Michigan State University/Department of Energy Plant Research Laboratory and Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA
| | - Jiří Friml
- Department of Functional Genomics and Proteomics, Central European Institute of Technology (CEITEC), Masaryk University, 62500 Brno, Czech Republic
- Institute of Science and Technology Austria (IST Austria), 3400 Klosterneuburg, Austria
| | - Federica Brandizzi
- Michigan State University/Department of Energy Plant Research Laboratory and Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA
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102
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Choi CM, Gray WM, Mooney S, Hellmann H. Composition, roles, and regulation of cullin-based ubiquitin e3 ligases. THE ARABIDOPSIS BOOK 2014; 12:e0175. [PMID: 25505853 PMCID: PMC4262284 DOI: 10.1199/tab.0175] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Due to their sessile nature, plants depend on flexible regulatory systems that allow them to adequately regulate developmental and physiological processes in context with environmental cues. The ubiquitin proteasome pathway, which targets a great number of proteins for degradation, is cellular tool that provides the necessary flexibility to accomplish this task. Ubiquitin E3 ligases provide the needed specificity to the pathway by selectively binding to particular substrates and facilitating their ubiquitylation. The largest group of E3 ligases known in plants is represented by CULLIN-REALLY INTERESTING NEW GENE (RING) E3 ligases (CRLs). In recent years, a great amount of knowledge has been generated to reveal the critical roles of these enzymes across all aspects of plant life. This review provides an overview of the different classes of CRLs in plants, their specific complex compositions, the variety of biological processes they control, and the regulatory steps that can affect their activities.
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Affiliation(s)
| | | | | | - Hanjo Hellmann
- Washington State University, Pullman, Washington
- Address correspondence to
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103
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Wang YL, Li Q, Xie J, Zhu M, Sun WJ, He L, Wang Q. Involvement of the single Cul4 gene of Chinese mitten crab Eriocheir sinensis in spermatogenesis. Gene 2013; 536:9-17. [PMID: 24334119 DOI: 10.1016/j.gene.2013.11.099] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2013] [Revised: 11/13/2013] [Accepted: 11/13/2013] [Indexed: 12/21/2022]
Abstract
The Cullin-RING finger ligases (CRLs) are involved in the ubiquitin-mediated degradation of cell cycle regulators and play an important role in gametogenesis. Cullin 4 (CUL4) is a conserved core component of a new class of ubiquitin E3 ligase, and participates in the proteolysis of several regulatory proteins through the ubiquitin-proteasome pathway. The mammals encode two paralogs of CUL4, CUL4A and CUL4B, and the two Cul4 genes are functionally redundant. However, Drosophila or other metazoans only contain one Cul4 gene. Here we cloned the Cul4 gene and confirmed that there is only one protein of CUL4 in Eriocheir sinensis, a full length Cul4 comprised of 2777 nucleotides, an open-reading frame of 2373bp encoding 790 amino acid residues. The expression level of Cul4 mRNAs, as demonstrated by quantitative real-time PCR, varied significantly during testis development, with the greatest transcript levels found at an early stage. Localization analysis using antibodies against CUL4A/4B in the reproductive system showed that EsCUL4 mainly distribute in spermatogonia and primary spermatocytes, and gradually reduced during the development and maturation of sperm. The results indicated that a single CUL4 protein may play a role in spermatogenesis in E. sinensis.
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Affiliation(s)
- Yuan-Li Wang
- School of Life Science, East China Normal University, Shanghai, China
| | - Qing Li
- School of Life Science, East China Normal University, Shanghai, China
| | - Jing Xie
- School of Life Science, East China Normal University, Shanghai, China
| | - Ming Zhu
- School of Life Science, East China Normal University, Shanghai, China
| | - Wen-Juan Sun
- School of Life Science, East China Normal University, Shanghai, China
| | - Lin He
- School of Life Science, East China Normal University, Shanghai, China.
| | - Qun Wang
- School of Life Science, East China Normal University, Shanghai, China.
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104
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Peer WA. From perception to attenuation: auxin signalling and responses. CURRENT OPINION IN PLANT BIOLOGY 2013; 16:561-8. [PMID: 24004572 DOI: 10.1016/j.pbi.2013.08.003] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Revised: 08/09/2013] [Accepted: 08/14/2013] [Indexed: 05/10/2023]
Abstract
The plant hormone auxin is essential for growth, development, and responses to environmental factors. Recently, Auxin Binding Protein 1 was shown to mediate non-transcriptional auxin signalling at the cell periphery. This has provoked reexamination of the paradigm that all auxin perception is intracellular and is mediated by the TIR1/AFB-Aux/IAA co-receptors for which auxin functions as a concentration-dependent molecular glue. Further, another F-box protein, SKP2a, was shown to bind auxin in the same way as TIR1/AFB, which provides a link to the role of auxin in the cell cycle. New work on auxin signalling and homeostasis include D6 PROTEIN KINASE activation of PINFORMED (PIN) auxin carriers, ROP-GTPase mediation of PIN localization, endoplasmic reticulum localization PIN and PIN-LIKES auxin carriers, and auxin biosynthesis and metabolism.
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Affiliation(s)
- Wendy Ann Peer
- Department of Environmental Science and Technology, University of Maryland, 5138 Plant Science Building, College Park, MD 20742, USA; Department of Plant Science and Landscape Architecture, University of Maryland, 5138 Plant Science Building, College Park, MD 20742, USA.
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105
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Franciosini A, Lombardi B, Iafrate S, Pecce V, Mele G, Lupacchini L, Rinaldi G, Kondou Y, Gusmaroli G, Aki S, Tsuge T, Deng XW, Matsui M, Vittorioso P, Costantino P, Serino G. The Arabidopsis COP9 SIGNALOSOME INTERACTING F-BOX KELCH 1 protein forms an SCF ubiquitin ligase and regulates hypocotyl elongation. MOLECULAR PLANT 2013; 6:1616-29. [PMID: 23475998 DOI: 10.1093/mp/sst045] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The regulation of protein turnover by the ubiquitin proteasome system (UPS) is a major posttranslational mechanism in eukaryotes. One of the key components of the UPS, the COP9 signalosome (CSN), regulates 'cullin-ring' E3 ubiquitin ligases. In plants, CSN participates in diverse cellular and developmental processes, ranging from light signaling to cell cycle control. In this work, we isolated a new plant-specific CSN-interacting F-box protein, which we denominated CFK1 (COP9 INTERACTING F-BOX KELCH 1). We show that, in Arabidopsis thaliana, CFK1 is a component of a functional ubiquitin ligase complex. We also show that CFK1 stability is regulated by CSN and by proteasome-dependent proteolysis, and that light induces accumulation of the CFK1 transcript in the hypocotyl. Analysis of CFK1 knockdown, mutant, and overexpressing seedlings indicates that CFK1 promotes hypocotyl elongation by increasing cell size. Reduction of CSN levels enhances the short hypocotyl phenotype of CFK1-depleted seedlings, while complete loss of CSN activity suppresses the long-hypocotyl phenotype of CFK1-overexpressing seedlings. We propose that CFK1 (and its regulation by CSN) is a novel component of the cellular mechanisms controlling hypocotyl elongation.
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Affiliation(s)
- Anna Franciosini
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Italy
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106
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Turner M, Nizampatnam NR, Baron M, Coppin S, Damodaran S, Adhikari S, Arunachalam SP, Yu O, Subramanian S. Ectopic expression of miR160 results in auxin hypersensitivity, cytokinin hyposensitivity, and inhibition of symbiotic nodule development in soybean. PLANT PHYSIOLOGY 2013; 162:2042-55. [PMID: 23796794 PMCID: PMC3729781 DOI: 10.1104/pp.113.220699] [Citation(s) in RCA: 124] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 06/22/2013] [Indexed: 05/18/2023]
Abstract
Symbiotic root nodules in leguminous plants result from interaction between the plant and nitrogen-fixing rhizobia bacteria. There are two major types of legume nodules, determinate and indeterminate. Determinate nodules do not have a persistent meristem, while indeterminate nodules have a persistent meristem. Auxin is thought to play a role in the development of both these types of nodules. However, inhibition of rootward auxin transport at the site of nodule initiation is crucial for the development of indeterminate nodules but not determinate nodules. Using the synthetic auxin-responsive DR5 promoter in soybean (Glycine max), we show that there is relatively low auxin activity during determinate nodule initiation and that it is restricted to the nodule periphery subsequently during development. To examine if and what role auxin plays in determinate nodule development, we generated soybean composite plants with altered sensitivity to auxin. We overexpressed microRNA393 to silence the auxin receptor gene family, and these roots were hyposensitive to auxin. These roots nodulated normally, suggesting that only minimal/reduced auxin signaling is required for determinate nodule development. We overexpressed microRNA160 to silence a set of repressor auxin response factor transcription factors, and these roots were hypersensitive to auxin. These roots were not impaired in epidermal responses to rhizobia but had significantly reduced nodule primordium formation, suggesting that auxin hypersensitivity inhibits nodule development. These roots were also hyposensitive to cytokinin and had attenuated expression of key nodulation-associated transcription factors known to be regulated by cytokinin. We propose a regulatory feedback loop involving auxin and cytokinin during nodulation.
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Affiliation(s)
| | | | - Mathieu Baron
- Department of Plant Science (M.T., N.R.N., M.B., S.C., S.D., S.A., S.P.A., S.S.) and Department of Biology and Microbiology (S.S.), South Dakota State University, Brookings, South Dakota 57007
- Ecole Nationale Supérieure Agronomique, BP32607 Auzeville-Tolosane, France (M.B., S.C.); and
- Donald Danforth Plant Science Center, St. Louis, Missouri 63132 (O.Y.)
| | - Stéphanie Coppin
- Department of Plant Science (M.T., N.R.N., M.B., S.C., S.D., S.A., S.P.A., S.S.) and Department of Biology and Microbiology (S.S.), South Dakota State University, Brookings, South Dakota 57007
- Ecole Nationale Supérieure Agronomique, BP32607 Auzeville-Tolosane, France (M.B., S.C.); and
- Donald Danforth Plant Science Center, St. Louis, Missouri 63132 (O.Y.)
| | - Suresh Damodaran
- Department of Plant Science (M.T., N.R.N., M.B., S.C., S.D., S.A., S.P.A., S.S.) and Department of Biology and Microbiology (S.S.), South Dakota State University, Brookings, South Dakota 57007
- Ecole Nationale Supérieure Agronomique, BP32607 Auzeville-Tolosane, France (M.B., S.C.); and
- Donald Danforth Plant Science Center, St. Louis, Missouri 63132 (O.Y.)
| | - Sajag Adhikari
- Department of Plant Science (M.T., N.R.N., M.B., S.C., S.D., S.A., S.P.A., S.S.) and Department of Biology and Microbiology (S.S.), South Dakota State University, Brookings, South Dakota 57007
- Ecole Nationale Supérieure Agronomique, BP32607 Auzeville-Tolosane, France (M.B., S.C.); and
- Donald Danforth Plant Science Center, St. Louis, Missouri 63132 (O.Y.)
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107
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Huang H, Quint M, Gray WM. The eta7/csn3-3 auxin response mutant of Arabidopsis defines a novel function for the CSN3 subunit of the COP9 signalosome. PLoS One 2013; 8:e66578. [PMID: 23762492 PMCID: PMC3676356 DOI: 10.1371/journal.pone.0066578] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Accepted: 05/07/2013] [Indexed: 12/02/2022] Open
Abstract
The COP9 signalosome (CSN) is an eight subunit protein complex conserved in all higher eukaryotes. In Arabidopsis thaliana, the CSN regulates auxin response by removing the ubiquitin-like protein NEDD8/RUB1 from the CUL1 subunit of the SCF(TIR1/AFB) ubiquitin-ligase (deneddylation). Previously described null mutations in any CSN subunit result in the pleiotropic cop/det/fus phenotype and cause seedling lethality, hampering the study of CSN functions in plant development. In a genetic screen to identify enhancers of the auxin response defects conferred by the tir1-1 mutation, we identified a viable csn mutant of subunit 3 (CSN3), designated eta7/csn3-3. In addition to enhancing tir1-1 mutant phenotypes, the csn3-3 mutation alone confers several phenotypes indicative of impaired auxin signaling including auxin resistant root growth and diminished auxin responsive gene expression. Unexpectedly however, csn3-3 plants are not defective in either the CSN-mediated deneddylation of CUL1 or in SCF(TIR1)-mediated degradation of Aux/IAA proteins. These findings suggest that csn3-3 is an atypical csn mutant that defines a novel CSN or CSN3-specific function. Consistent with this possibility, we observe dramatic differences in double mutant interactions between csn3-3 and other auxin signaling mutants compared to another weak csn mutant, csn1-10. Lastly, unlike other csn mutants, assembly of the CSN holocomplex is unaffected in csn3-3 plants. However, we detected a small CSN3-containing protein complex that is altered in csn3-3 plants. We hypothesize that in addition to its role in the CSN as a cullin deneddylase, CSN3 functions in a distinct protein complex that is required for proper auxin signaling.
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Affiliation(s)
- He Huang
- Department of Plant Biology, University of Minnesota, St. Paul, Minnesota, United States of America
| | - Marcel Quint
- Department of Plant Biology, University of Minnesota, St. Paul, Minnesota, United States of America
| | - William M. Gray
- Department of Plant Biology, University of Minnesota, St. Paul, Minnesota, United States of America
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108
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Golenberg EM, West NW. Hormonal interactions and gene regulation can link monoecy and environmental plasticity to the evolution of dioecy in plants. AMERICAN JOURNAL OF BOTANY 2013; 100:1022-37. [PMID: 23538873 DOI: 10.3732/ajb.1200544] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Most models for dioecy in flowering plants assume that dioecy arises directly from hermaphroditism through a series of independent feminizing and masculinizing mutations that become chromosomally linked. However, dioecy appears to evolve most frequently through monoecious grades. The major genetic models do not explain the evolution of unisexual flowers in monoecious and submonoecious populations, nor do they account for environmentally induced sexual plasticity. In this review, we explore the roles of environmental stress and hormones on sex determination, and propose a model that can explain the evolution of dioecy through monoecy, and the mechanisms of environmental sex determination. Environmental stresses elicit hormones that allow plants to mediate the negative effects of the stresses. Many of these same hormones are involved in the regulation of floral developmental genes. Recent studies have elucidated the mechanisms whereby these hormones interact and can act as switchpoints in regulatory pathways. Consequently, differential concentrations of plant hormones can regulate whole developmental pathways, providing a mechanism for differential development within isogenic individuals such as seen in monoecious plants. Sex-determining genes in such systems will evolve to generate clusters of coexpressed suites. Coexpression rather than coinheritance of gender-specific genes will define the sexual developmental fate. Therefore, selection for gender type will drive evolution of the regulatory sequences of such genes rather than their synteny. Subsequent mutations to hyper- or hyposensitive alleles within the hormone response pathway can result in segregating dioecious populations. Simultaneously, such developmental systems will remain sensitive to external stimuli that modify hormone responses.
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Affiliation(s)
- Edward M Golenberg
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA.
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109
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Milhinhos A, Miguel CM. Hormone interactions in xylem development: a matter of signals. PLANT CELL REPORTS 2013; 32:867-83. [PMID: 23532297 DOI: 10.1007/s00299-013-1420-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2012] [Revised: 03/03/2013] [Accepted: 03/08/2013] [Indexed: 05/21/2023]
Abstract
Xylem provides long-distance transport of water and nutrients as well as structural support in plants. The development of the xylem tissues is modulated by several internal signals. In the last decades, the bloom of genetic and genomic tools has led to increased understanding of the molecular mechanisms underlying the function of the traditional plant hormones in xylem specification and differentiation. Critical functions have been assigned to novel signaling molecules, such as thermospermine. These signals do not function independently, but interact in a manner we are only now beginning to understand. We review the current knowledge of hormone signaling pathways and their crosstalk in cambial cell initiation and maintenance, and in xylem specification and differentiation.
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Affiliation(s)
- Ana Milhinhos
- Instituto de Biologia Experimental e Tecnológica, Apartado 12, 2781-901 Oeiras, Portugal.
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110
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Esteve-Bruna D, Pérez-Pérez JM, Ponce MR, Micol JL. incurvata13, a novel allele of AUXIN RESISTANT6, reveals a specific role for auxin and the SCF complex in Arabidopsis embryogenesis, vascular specification, and leaf flatness. PLANT PHYSIOLOGY 2013; 161:1303-20. [PMID: 23319550 PMCID: PMC3585598 DOI: 10.1104/pp.112.207779] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Auxin plays a pivotal role in plant development by modulating the activity of SCF ubiquitin ligase complexes. Here, we positionally cloned Arabidopsis (Arabidopsis thaliana) incurvata13 (icu13), a mutation that causes leaf hyponasty and reduces leaf venation pattern complexity and auxin responsiveness. We found that icu13 is a novel recessive allele of AUXIN RESISTANT6 (AXR6), which encodes CULLIN1, an invariable component of the SCF complex. Consistent with a role for auxin in vascular specification, the vascular defects in the icu13 mutant were accompanied by reduced expression of auxin transport and auxin perception markers in provascular cells. This observation is consistent with the expression pattern of AXR6, which we found to be restricted to vascular precursors and hydathodes in wild-type leaf primordia. AXR1, RELATED TO UBIQUITIN1-CONJUGATING ENZYME1, CONSTITUTIVE PHOTOMORPHOGENIC9 SIGNALOSOME5A, and CULLIN-ASSOCIATED NEDD8-DISSOCIATED1 participate in the covalent modification of CULLIN1 by RELATED TO UBIQUITIN. Hypomorphic alleles of these genes also display simple venation patterns, and their double mutant combinations with icu13 exhibited a synergistic, rootless phenotype reminiscent of that caused by loss of function of MONOPTEROS (MP), which forms an auxin-signaling module with BODENLOS (BDL). The phenotypes of double mutant combinations of icu13 with either a gain-of-function allele of BDL or a loss-of-function allele of MP were synergistic. In addition, a BDL:green fluorescent protein fusion protein accumulated in icu13, and BDL loss of function or MP overexpression suppressed the phenotype of icu13. Our results demonstrate that the MP-BDL module is required not only for root specification in embryogenesis and vascular postembryonic development but also for leaf flatness.
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111
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A comprehensive analysis of interaction and localization of Arabidopsis SKP1-like (ASK) and F-box (FBX) proteins. PLoS One 2012; 7:e50009. [PMID: 23166809 PMCID: PMC3499479 DOI: 10.1371/journal.pone.0050009] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Accepted: 10/15/2012] [Indexed: 11/20/2022] Open
Abstract
F-Box (FBX) proteins are encoded by a multigene family present in major lineages of eukaryotes. A number of FBX proteins are shown to be subunits of SCF complex, a type of E3 ligases composed of SKP1, CULLIN, FBX and RBX1 proteins. The Arabidopsis SKP-LIKE (ASK) proteins are also members of a family and some of them interact with FBX proteins directly. To clarify how FBX and ASK proteins combine, we carried out a large-scale interaction analysis between FBX and ASK proteins using yeast two-hybrid assay (Y2H) in Arabidopsis thaliana. FBX proteins randomly chosen from those proteins that interacted with more than one ASK protein were further analyzed for their subcellular localization and in vivo interaction with ASK proteins. Furthermore, the expression profiles of FBX and ASK genes were compared. This work reveals that FBX proteins had a preference for interacting with ASK proteins depending on the domains they contain such as the FBX-associated (FBA) domain, the Kelch domain and leucine rich repeat (LRR). In addition, it was found that a single FBX protein could form multiple SCF complexes by interacting with several ASK proteins in many cases. Furthermore, it was suggested that the variation of SCF complexes were especially abundant in tissues related to male gametophyte and seed development. More than half of the FBX proteins studied did not interact with any of the ASK proteins, implying the necessity for certain regulations for their interaction in vivo and/or distinct roles from subunits of the SCF complex.
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112
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Sepúlveda-García E, Rocha-Sosa M. The Arabidopsis F-box protein AtFBS1 interacts with 14-3-3 proteins. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2012; 195:36-47. [PMID: 22920997 DOI: 10.1016/j.plantsci.2012.06.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 06/14/2012] [Accepted: 06/16/2012] [Indexed: 05/24/2023]
Abstract
AtFBS1 is an F-box protein whose transcript accumulates in response to biotic and abiotic stresses. Previous evidence suggests that a postranscriptional event regulates AtFBS1 expression [1]. We now found that AtFBS1 interacts with 14-3-3 proteins through its amino-terminus and the F-box motif. Deletion of any of these regions abolishes the interaction between AtFBS1 and 14-3-3 proteins. On the other hand, the treatment with the proteasome inhibitor MG132 or the deletion of the F-box from AtFBS1 increases β-glucuronidase (GUS) activity in plants containing a translational fusion of AtFBS1 with the GUS reporter gene, indicating that AtFBS1 is degraded by the 26S proteasome. MG132 treatment of seedlings containing a gene fusion between AtFBS1 and the TAP (Tandem Affinity Purification) cassette causes an increase in the half-life of the protein. In an attempt to understand the role of 14-3-3 interactions, we treated Arabidopsis seedlings with 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranosyl 5'-monophosphate (AICAR), an inhibitor of 14-3-3 client interactions. We observed an increase in AtFBS1-TAP stability as a consequence of AICAR treatment. Based on these data we propose that 14-3-3 proteins promote the dimerization of SCF(AtFBS1). This also may enhance the AtFBS1 autoubiquitination activity and its degradation by the 26S proteasome. AICAR also affects Cullin1 (CUL1) modification by RUB1, which would provide an additional element to the effect of this compound on AtFBS1 stability.
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Affiliation(s)
- Edgar Sepúlveda-García
- Departamento de Biología Molecular de Plantas, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo Postal 510-3, Cuernavaca, Mor, 62250, Mexico.
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113
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Hong MJ, Kim DY, Kang SY, Kim DS, Kim JB, Seo YW. Wheat F-box protein recruits proteins and regulates their abundance during wheat spike development. Mol Biol Rep 2012; 39:9681-96. [PMID: 22729884 DOI: 10.1007/s11033-012-1833-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Accepted: 06/10/2012] [Indexed: 10/28/2022]
Abstract
F-box proteins, components of the Skp1-Cullin1-F-box (SCF) protein E3 ubiquitin ligase complex, serve as the variable component responsible for substrate recognition and recruitment in SCF-mediated proteolysis. F-box proteins interact with Skp1 through the F-box motif and with ubiquitination substrates through C-terminal protein interaction domains. F-box proteins regulate plant development, various hormonal signal transduction processes, circadian rhythm, and cell cycle control. We isolated an F-box protein gene from wheat spikes at the onset of flowering. The Triticum aestivum cyclin F-box domain (TaCFBD) gene showed elevated expression levels during early inflorescence development and under cold stress treatment. TaCFBD green fluorescent protein signals were localized in the cytoplasm and plasma membrane. We used yeast two-hybrid screening to identify proteins that potentially interact with TaCFBD. Fructose bisphosphate aldolase, aspartic protease, VHS, glycine-rich RNA-binding protein, and the 26S proteasome non-ATPase regulatory subunit were positive candidate proteins. The bimolecular fluorescence complementation assay revealed the interaction of TaCFBD with partner proteins in the plasma membranes of tobacco cells. Our results suggest that the TaCFBD protein acts as an adaptor between target substrates and the SCF complex and provides substrate specificity to the SCF of ubiquitin ligase complexes.
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Affiliation(s)
- Min Jeong Hong
- Division of Biotechnology, Korea University, Anam-Dong, Seongbuk-Gu, Seoul 136-701, Republic of Korea
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114
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Arase F, Nishitani H, Egusa M, Nishimoto N, Sakurai S, Sakamoto N, Kaminaka H. IAA8 involved in lateral root formation interacts with the TIR1 auxin receptor and ARF transcription factors in Arabidopsis. PLoS One 2012; 7:e43414. [PMID: 22912871 PMCID: PMC3422273 DOI: 10.1371/journal.pone.0043414] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Accepted: 07/20/2012] [Indexed: 11/18/2022] Open
Abstract
The expression of auxin-responsive genes is regulated by the TIR1/AFB auxin receptor-dependent degradation of Aux/IAA transcriptional repressors, which interact with auxin-responsive factors (ARFs). Most of the 29 Aux/IAA genes present in Arabidopsis have not been functionally characterized to date. IAA8 appears to have a distinct function from the other Aux/IAA genes, due to its unique transcriptional response to auxin and the stability of its encoded protein. In this study, we characterized the function of Arabidopsis IAA8 in various developmental processes governed by auxin and in the transcriptional regulation of the auxin response. Transgenic plants expressing estrogen-inducible IAA8 (XVE::IAA8) exhibited significantly fewer lateral roots than the wild type, and an IAA8 loss-of-function mutant exhibited significantly more. Ectopic overexpression of IAA8 resulted in abnormal gravitropism. The strong induction of early auxin-responsive marker genes by auxin treatment was delayed by IAA8 overexpression. GFP-fusion analysis revealed that IAA8 localized not only to the nucleus, but, in contrast to other Aux/IAAs, also to the cytosol. Furthermore, we demonstrated that IAA8 interacts with TIR1, in an auxin-dependent fashion, and with ARF proteins, both in yeast and in planta. Taken together, our results show that IAA8 is involved in lateral root formation, and that this process is regulated through the interaction with the TIR1 auxin receptor and ARF transcription factors in the nucleus.
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Affiliation(s)
- Fumi Arase
- Laboratory of Plant Molecular Biology, Faculty of Agriculture, Tottori University, Tottori, Japan
| | - Hiroko Nishitani
- Laboratory of Plant Molecular Biology, Faculty of Agriculture, Tottori University, Tottori, Japan
| | - Mayumi Egusa
- Laboratory of Plant Molecular Biology, Faculty of Agriculture, Tottori University, Tottori, Japan
| | - Nami Nishimoto
- Laboratory of Plant Molecular Biology, Faculty of Agriculture, Tottori University, Tottori, Japan
| | - Sumiko Sakurai
- Laboratory of Plant Molecular Biology, Faculty of Agriculture, Tottori University, Tottori, Japan
| | - Naho Sakamoto
- Laboratory of Plant Molecular Biology, Faculty of Agriculture, Tottori University, Tottori, Japan
| | - Hironori Kaminaka
- Laboratory of Plant Molecular Biology, Faculty of Agriculture, Tottori University, Tottori, Japan
- * E-mail:
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115
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Hu Y, Yang L, Na X, You J, Hu W, Liang X, Liu J, Mao L, Wang X, Wang H, Bi Y. Narciclasine inhibits the responses of Arabidopsis roots to auxin. PLANTA 2012; 236:597-612. [PMID: 22476291 DOI: 10.1007/s00425-012-1632-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Accepted: 03/22/2012] [Indexed: 05/31/2023]
Abstract
The plant hormone auxin plays a central role in the regulation of plant growth and development, as well as in responses to environmental stimuli. Narciclasine (NCS, an Amaryllidaceae alkaloid) isolated from Narcissus tazetta bulbs has a broad range of inhibitory effects on plants. In this study, the role of NCS in responses to auxin in Arabidopsis thaliana roots was investigated. We demonstrated the inhibitory effects of NCS on auxin-inducible lateral root formation, root hair formation, primary root growth, and the expression of primary auxin-inducible genes in Arabidopsis roots using DR5::GUS reporter gene, native auxin promoters (IAA12::GUS, IAA13::GUS), and quantitative reverse transcription PCR analysis. Results also showed that NCS did not affect the expression of cytokinin-inducible ARR5::GUS reporter gene. NCS relieved the auxin-enhanced degradation of the Aux/IAA repressor modulated by the SCFTIR1 ubiquitin-proteasome pathway. In addition, NCS did not alter the auxin-stimulated interaction between IAA7/AXR2 (Aux/IAA proteins) and the F-box protein TIR1 activity of the proteasome. Taken together, these results suggest that NCS acts on the auxin signaling pathway upstream of TIR1, which modulates Aux/IAA protein degradation, and thereby affects the auxin-mediated responses in Arabidopsis roots.
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Affiliation(s)
- Yanfeng Hu
- School of Life Sciences, Lanzhou University, Lanzhou, 730000, People's Republic of China
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116
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Yang X, Liu X, Lv W, Li L, Shi Q, Yang J, Zhang M. Reduced expression of BjRCE1 gene modulated by nuclear-cytoplasmic incompatibility alters auxin response in cytoplasmic male-sterile Brassica juncea. PLoS One 2012; 7:e38821. [PMID: 22719957 PMCID: PMC3377708 DOI: 10.1371/journal.pone.0038821] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Accepted: 05/11/2012] [Indexed: 11/30/2022] Open
Abstract
The signal from organelle to nucleus, namely retrograde regulation of nuclear gene expression, was largely unknown. Due to the nuclear-cytoplasmic incompatibility in cytoplasmic male-sterile (CMS) plants, we employed CMS Brassica juncea to investigate the retrograde regulation of nuclear gene expression in this study. We studied how reduced BjRCE1 gene expression caused by the nuclear-cytoplasmic incompatibility altered the auxin response in CMS of B. juncea. We isolated the BjRCE1 gene that was located in the nucleus from B. juncea. Over-expression of BjRCE1 enhanced auxin response in transgenic Arabidopsis. The expression of BjRCE1 was significantly reduced in CMS compared with its maintainer fertile (MF) line of B. juncea. There were fewer lateral roots in CMS than MF under normal and treatment of indole-3-acetic acid (IAA) conditions. Expression patterns of several auxin-related genes together with their phenotypes indicated a reduced auxin response in CMS compared to MF. The phenotypes of auxin response and auxin-related gene expression pattern could be mimicked by inhibiting mitochondrial function in MF. Taken together, we proposed reduced expression of BjRCE1 gene modulated by nuclear-cytoplasmic incompatibility alters auxin response in CMS B. juncea. This may be an important mechanism of retrograde regulation of nuclear gene expression in plants.
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Affiliation(s)
- Xiaodong Yang
- Laboratory of Germplasm Innovation and Molecular Breeding, Institute of Vegetable Science, Zhejiang University, Hangzhou, People’s Republic of China
- Key Laboratory of Horticultural Plant Growth, Development & Quality Improvement, Ministry of Agriculture, Hangzhou, People’s Republic of China
| | - Xunyan Liu
- College of Life and Environment Sciences, Hangzhou Normal University, Hangzhou, People’s Republic of China
| | - Wenhui Lv
- Laboratory of Germplasm Innovation and Molecular Breeding, Institute of Vegetable Science, Zhejiang University, Hangzhou, People’s Republic of China
- Key Laboratory of Horticultural Plant Growth, Development & Quality Improvement, Ministry of Agriculture, Hangzhou, People’s Republic of China
| | - Lu Li
- Laboratory of Germplasm Innovation and Molecular Breeding, Institute of Vegetable Science, Zhejiang University, Hangzhou, People’s Republic of China
- Key Laboratory of Horticultural Plant Growth, Development & Quality Improvement, Ministry of Agriculture, Hangzhou, People’s Republic of China
| | - Qianqian Shi
- Laboratory of Germplasm Innovation and Molecular Breeding, Institute of Vegetable Science, Zhejiang University, Hangzhou, People’s Republic of China
- Key Laboratory of Horticultural Plant Growth, Development & Quality Improvement, Ministry of Agriculture, Hangzhou, People’s Republic of China
| | - Jinghua Yang
- Laboratory of Germplasm Innovation and Molecular Breeding, Institute of Vegetable Science, Zhejiang University, Hangzhou, People’s Republic of China
- Key Laboratory of Horticultural Plant Growth, Development & Quality Improvement, Ministry of Agriculture, Hangzhou, People’s Republic of China
| | - Mingfang Zhang
- Laboratory of Germplasm Innovation and Molecular Breeding, Institute of Vegetable Science, Zhejiang University, Hangzhou, People’s Republic of China
- Key Laboratory of Horticultural Plant Growth, Development & Quality Improvement, Ministry of Agriculture, Hangzhou, People’s Republic of China
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117
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Chen H, Li Z, Xiong L. A plant microRNA regulates the adaptation of roots to drought stress. FEBS Lett 2012; 586:1742-7. [PMID: 22613571 DOI: 10.1016/j.febslet.2012.05.013] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Revised: 05/08/2012] [Accepted: 05/08/2012] [Indexed: 12/30/2022]
Abstract
Plants tend to restrict their horizontal root proliferation in response to drought stress, an adaptive response mediated by the phytohormone abscisic acid (ABA) in antagonism with auxin through unknown mechanisms. Here, we found that stress-regulated miR393-guided cleavage of the transcripts encoding two auxin receptors, TIR1 and AFB2, was required for inhibition of lateral root growth by ABA or osmotic stress. Unlike in the control plants, the lateral root growth of seedlings expressing miR393-resistant TIR1 or AFB2 was no longer inhibited by ABA or osmotic stress. Our results indicate that miR393-mediated attenuation of auxin signaling modulates root adaptation to drought stress.
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Affiliation(s)
- Hao Chen
- Donald Danforth Plant Science Center, St. Louis, MO 63132, USA
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118
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Stratmann JW, Gusmaroli G. Many jobs for one good cop - the COP9 signalosome guards development and defense. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2012; 185-186:50-64. [PMID: 22325866 DOI: 10.1016/j.plantsci.2011.10.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 10/10/2011] [Accepted: 10/11/2011] [Indexed: 05/08/2023]
Abstract
The COP9 signalosome (CSN) is a multiprotein complex that regulates the activity of CULLIN-RING E3 ubiquitin ligases (CRLs). CRLs ubiquitinate substrate proteins and thus target them for proteasomal degradation. This post-translational modification of proteins is arguably as important as reversible protein phosphorylation. The number of putative CRLs that recognize specific substrate proteins is vast, and known CRL substrates are involved in many cellular plant processes such as hormone signaling, the cell cycle, and regulation of growth, development, and defenses. By controlling the activity of CRLs, the CSN may integrate and fine-tune all of these processes. Recent research has unraveled in great mechanistic detail how the two multiprotein complexes CSN and CRL interact. As a consequence of CSN pleiotropy, complete loss of CSN function results in seedling lethality. However, recent work on plants that exhibit a partial loss of CSN function, has uncovered a role of the CSN during later life stages in processes such as development and defenses against pathogens and herbivorous insects. Not all aspects of development and defense are affected equally by CSN silencing, probably due to the differential participation and importance of CSN-regulated CRLs in these processes. This review will provide an overview of the highly complex regulation of CRL activity by CSN, and the many roles of the CSN in plant development and defense.
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Affiliation(s)
- Johannes W Stratmann
- University of South Carolina, Department of Biological Sciences, Columbia, SC 29208, USA.
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119
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Capron D, Mouzeyar S, Boulaflous A, Girousse C, Rustenholz C, Laugier C, Paux E, Bouzidi MF. Transcriptional profile analysis of E3 ligase and hormone-related genes expressed during wheat grain development. BMC PLANT BIOLOGY 2012; 12:35. [PMID: 22416807 PMCID: PMC3405487 DOI: 10.1186/1471-2229-12-35] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Accepted: 03/14/2012] [Indexed: 05/23/2023]
Abstract
BACKGROUND Wheat grains are an important source of food, stock feed and raw materials for industry, but current production levels cannot meet world needs. Elucidation of the molecular mechanisms underlying wheat grain development will contribute valuable information to improving wheat cultivation. One of the most important mechanisms implicated in plant developmental processes is the ubiquitin-proteasome system (UPS). Among the different roles of the UPS, it is clear that it is essential to hormone signaling. In particular, E3 ubiquitin ligases of the UPS have been shown to play critical roles in hormone perception and signal transduction. RESULTS A NimbleGen microarray containing 39,179 UniGenes was used to study the kinetics of gene expression during wheat grain development from the early stages of cell division to the mid-grain filling stage. By comparing 11 consecutive time-points, 9284 differentially expressed genes were identified and annotated during this study. A comparison of the temporal profiles of these genes revealed dynamic transcript accumulation profiles with major reprogramming events that occurred during the time intervals of 80-120 and 220-240°Cdays. The list of the genes expressed differentially during these transitions were identified and annotated. Emphasis was placed on E3 ligase and hormone-related genes. In total, 173 E3 ligase coding genes and 126 hormone-related genes were differentially expressed during the cell division and grain filling stages, with each family displaying a different expression profile. CONCLUSIONS The differential expression of genes involved in the UPS and plant hormone pathways suggests that phytohormones and UPS crosstalk might play a critical role in the wheat grain developmental process. Some E3 ligase and hormone-related genes seem to be up- or down-regulated during the early and late stages of the grain development.
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Affiliation(s)
- Delphine Capron
- Université Blaise Pascal, UMR 1095 GDEC, 24 avenue des Landais, F-63177 Aubière, France
| | - Said Mouzeyar
- Université Blaise Pascal, UMR 1095 GDEC, 24 avenue des Landais, F-63177 Aubière, France
| | - Aurélia Boulaflous
- Université Blaise Pascal, UMR 1095 GDEC, 24 avenue des Landais, F-63177 Aubière, France
| | - Christine Girousse
- INRA, UMR 1095 GDEC, 234 avenue du Brézet, F-63100 Clermont-Ferrand, France
| | - Camille Rustenholz
- INRA, UMR 1095 GDEC, 234 avenue du Brézet, F-63100 Clermont-Ferrand, France
| | - Christel Laugier
- INRA, UMR 1095 GDEC, 234 avenue du Brézet, F-63100 Clermont-Ferrand, France
| | - Etienne Paux
- INRA, UMR 1095 GDEC, 234 avenue du Brézet, F-63100 Clermont-Ferrand, France
| | - Mohamed Fouad Bouzidi
- Université Blaise Pascal, UMR 1095 GDEC, 24 avenue des Landais, F-63177 Aubière, France
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120
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Shan X, Yan J, Xie D. Comparison of phytohormone signaling mechanisms. CURRENT OPINION IN PLANT BIOLOGY 2012; 15:84-91. [PMID: 22001935 DOI: 10.1016/j.pbi.2011.09.006] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Revised: 09/15/2011] [Accepted: 09/20/2011] [Indexed: 05/31/2023]
Abstract
Plant hormones are crucial signaling molecules that coordinate all aspects of plant growth, development and defense. A great deal of attention has been attracted from biologists to study the molecular mechanisms for perception and signal transduction of plant hormones during the last two decades. Tremendous progress has been made in identifying receptors and key signaling components of plant hormones. The holistic picture of hormone signaling pathways is extremely complicated, this review will give a general overview of perception and signal transduction mechanisms of auxin, gibberellin, cytokinin, abscisic acid, ethylene, brassinosteroid, and jasmonate.
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Affiliation(s)
- Xiaoyi Shan
- School of Life Sciences, Tsinghua University, Beijing 100084, China
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121
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Functional diversification of the Tubby-like protein gene families (TULPs) during eukaryotic evolution. BIOCATALYSIS AND AGRICULTURAL BIOTECHNOLOGY 2012. [DOI: 10.1016/j.bcab.2011.08.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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122
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Walcher CL, Nemhauser JL. Bipartite promoter element required for auxin response. PLANT PHYSIOLOGY 2012; 158:273-82. [PMID: 22100645 PMCID: PMC3252081 DOI: 10.1104/pp.111.187559] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Accepted: 11/16/2011] [Indexed: 05/19/2023]
Abstract
Multiple mechanisms have been described for coordination of responses to the plant hormones auxin and brassinosteroids (Zhang et al., 2009). One unexplained phenomenon is the reliance of the auxin transcriptional response on a functional brassinosteroid pathway. In this study, we used luciferase reporters to interrogate the promoter of SMALL AUXIN-UP RNA15 (SAUR15), a well-characterized auxin and brassinosteroid early response gene in Arabidopsis (Arabidopsis thaliana). After identifying a minimal region sufficient for auxin response, we targeted predicted cis-regulatory elements contained within this sequence and found a critical subset required for hormone response. Specifically, reporter sensitivity to auxin treatment required two elements: a Hormone Up at Dawn (HUD)-type E-box and an AuxRE-related TGTCT element. Reporter response to brassinosteroid treatment relied on the same two elements. Consistent with these findings, the transcription factors BRASSINOSTEROID INSENSITIVE1-EMS SUPPESSOR1 and MONOPTEROS (MP)/ AUXIN RESPONSE FACTOR5 (ARF5) showed enhanced binding to the critical promoter region containing these elements. Treatment with auxin or brassinosteroids could enhance binding of either transcription factor, and brassinosteroid enhancement of MP/ARF5 binding required an intact HUD element. Conservation of clustered HUD elements and AuxRE-related sequences in promoters of putative SAUR15 orthologs in a number of flowering plant species, in combination with evidence for statistically significant clustering of these elements across all Arabidopsis promoters, provided further evidence of the functional importance of coordinated transcription factor binding.
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123
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Khan GA, Declerck M, Sorin C, Hartmann C, Crespi M, Lelandais-Brière C. MicroRNAs as regulators of root development and architecture. PLANT MOLECULAR BIOLOGY 2011; 77:47-58. [PMID: 21607657 DOI: 10.1007/s11103-011-9793-x] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2010] [Accepted: 05/09/2011] [Indexed: 05/18/2023]
Abstract
MicroRNAs (miRNAs) are post-transcriptional regulators of growth and development in both plants and animals. In plants, roots play essential roles in their anchorage to the soil as well as in nutrient and water uptake. In this review, we present recent advances made in the identification of miRNAs involved in embryonic root development, radial patterning, vascular tissue differentiation and formation of lateral organs (i.e., lateral and adventitious roots and symbiotic nitrogen-fixing nodules in legumes). Certain mi/siRNAs target members of the Auxin Response Factors family involved in auxin homeostasis and signalling and participate in complex regulatory loops at several crucial stages of root development. Other miRNAs target and restrict the action of various transcription factors that control root-related processes in several species. Finally, because abiotic stresses, which include nutrient or water deficiencies, generally modulate root growth and branching, we summarise the action of certain miRNAs in response to these stresses that may be involved in the adaptation of the root system architecture to the soil environment.
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Affiliation(s)
- Ghazanfar A Khan
- Institut des Sciences du Végétal, Centre National de la Recherche Scientifique (C.N.R.S.), 91198 Gif-sur-Yvette Cedex, France
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124
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Greenham K, Santner A, Castillejo C, Mooney S, Sairanen I, Ljung K, Estelle M. The AFB4 auxin receptor is a negative regulator of auxin signaling in seedlings. Curr Biol 2011; 21:520-5. [PMID: 21396817 DOI: 10.1016/j.cub.2011.02.029] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Revised: 01/21/2011] [Accepted: 02/19/2011] [Indexed: 11/30/2022]
Abstract
The plant hormone auxin is perceived by a family of F box proteins called the TIR1/auxin-signaling F box proteins (AFBs). Phylogenetic studies reveal that these proteins fall into four clades in flowering plants called TIR1, AFB2, AFB4, and AFB6. Genetic studies indicate that members of the TIR1 and AFB2 groups act as positive regulators of auxin signaling. In this report, we demonstrate a unique role for the AFB4 clade. Both AFB4 and AFB5 function as auxin receptors based on in vitro assays. However, unlike other members of the family, loss of AFB4 results in a range of growth defects that are consistent with auxin hypersensitivity, including increased hypocotyl and petiole elongation and increased numbers of lateral roots. Indeed, qRT-PCR experiments show that afb4-2 is hypersensitive to indole-3-acetic acid (IAA) in the hypocotyl, indicating that AFB4 is a negative regulator of auxin response. Furthermore, we show that AFB4 has a particularly important role in the response of seedlings to elevated temperature. Finally, we provide evidence that the AFB4 clade is the major target of the picloram family of auxinic herbicides. These results reveal a previously unknown aspect of auxin receptor function.
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Affiliation(s)
- Katie Greenham
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093, USA
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125
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Dai L, Xu L, Huang D, Li X, Luo K, Guan C. ASK1 physically interacts with COI1 and is required for male fertility in Arabidopsis. ACTA ACUST UNITED AC 2011; 45:631-6. [PMID: 18762895 DOI: 10.1007/bf02879751] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2001] [Indexed: 11/24/2022]
Abstract
Jasmonates are a new class of plant hormones that play important roles in plant development and plant defense. The COI1 gene was previously shown to be required for jasmonate-regulated plant fertility and defense. We demonstrated for the first time that COI1 interacts with the Arabidopsis SKP1-LIKE1 (ASK1) to form a complex that is required for jasmonate action in planta. Functional analysis by antisense strategy showed that ASK1 is involved in male fertility.
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126
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Mazzucotelli E, Belloni S, Marone D, De Leonardis A, Guerra D, Di Fonzo N, Cattivelli L, Mastrangelo A. The e3 ubiquitin ligase gene family in plants: regulation by degradation. Curr Genomics 2011; 7:509-22. [PMID: 18369404 DOI: 10.2174/138920206779315728] [Citation(s) in RCA: 175] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2006] [Revised: 10/19/2006] [Accepted: 10/22/2006] [Indexed: 02/02/2023] Open
Abstract
The regulation of protein expression and activity has been for long time considered only in terms of transcription/translation efficiency. In the last years, the discovery of post-transcriptional and post-translational regulation mechanisms pointed out that the key factor in determining transcript/protein amount is the synthesis/degradation ratio, together with post-translational modifications of proteins. Polyubiquitinaytion marks target proteins directed to degradation mediated by 26S-proteasome. Recent functional genomics studies pointed out that about 5% of Arabidopsis genome codes for proteins of ubiquitination pathway. The most of them (more than one thousand genes) correspond to E3 ubiquitin ligases that specifically recognise target proteins. The huge size of this gene family, whose members are involved in regulation of a number of biological processes including hormonal control of vegetative growth, plant reproduction, light response, biotic and abiotic stress tolerance and DNA repair, indicates a major role for protein degradation in control of plant life.
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Affiliation(s)
- E Mazzucotelli
- C.R.A.-Experimental Institute for Cereal Research, Section of Foggia, S.S. 16 km 675, 71100 Foggia, Italy
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127
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Ren Z, Li Z, Miao Q, Yang Y, Deng W, Hao Y. The auxin receptor homologue in Solanum lycopersicum stimulates tomato fruit set and leaf morphogenesis. JOURNAL OF EXPERIMENTAL BOTANY 2011; 62:2815-26. [PMID: 21266497 DOI: 10.1093/jxb/erq455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
TIR1 and its homologues act as auxin receptors and play a crucial role in auxin-mediated plant development. While the functions of auxin receptor genes have been widely studied in Arabidopsis thaliana, there has been no report on the consequences of TIR1 overexpression in plants that regulate fruit development. Here a putative tomato auxin receptor gene, homologous to Arabidopsis AtTIR1, is reported. This gene, designated as Solanum lycopersicum TIR1 (SlTIR1), was found to be expressed in all the parts of floral buds and flowers at anthesis stages. From bud to anthesis, SlTIR1 expression increases slightly in sepal tissue and decreases dramatically in stamen. From anthesis to post-anthesis when fruit set is expected to occur, the expression of SlTIR1 declines in the ovary and sepal. Overexpression of SlTIR1 results in a pleiotropic phenotype including parthenocarpic fruit formation and leaf morphology. Furthermore, SlTIR1 overexpression altered transcript levels of a number of auxin-responsive genes. The present data demonstrate that the tomato SlTIR1 gene plays an important role at the stages of flower-to-fruit transition and leaf formation.
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MESH Headings
- Amino Acid Sequence
- Base Sequence
- Cell Nucleus/metabolism
- DNA, Complementary/isolation & purification
- Flowers/genetics
- Flowers/growth & development
- Fruit/genetics
- Fruit/growth & development
- Gene Expression Profiling
- Gene Expression Regulation, Developmental
- Gene Expression Regulation, Plant
- Genome, Plant/genetics
- Solanum lycopersicum/genetics
- Solanum lycopersicum/growth & development
- Models, Biological
- Molecular Sequence Data
- Morphogenesis/genetics
- Organ Specificity/genetics
- Parthenogenesis/genetics
- Phenotype
- Phylogeny
- Plant Leaves/anatomy & histology
- Plant Leaves/genetics
- Plant Leaves/growth & development
- Plant Proteins/chemistry
- Plant Proteins/genetics
- Plant Proteins/metabolism
- Plants, Genetically Modified
- Protein Transport
- Receptors, Cell Surface/chemistry
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/metabolism
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Transcription, Genetic
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Affiliation(s)
- Zhenxin Ren
- Genetic Engineering Research Center, Bioengineering College, Chongqing University, Key Lab of Functional Gene and New Regulation Technologies under Chongqing Municipal Education Commission, Chongqing, 400030, PR China
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128
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An E3 ligase complex regulates SET-domain polycomb group protein activity in Arabidopsis thaliana. Proc Natl Acad Sci U S A 2011; 108:8036-41. [PMID: 21518870 DOI: 10.1073/pnas.1104232108] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Transcriptional repression via methylation of histone H3 lysine 27 (H3K27) by the polycomb repressive complex 2 (PRC2) is conserved in higher eukaryotes. The Arabidopsis PRC2 controls homeotic gene expression, flowering time, and gene imprinting. Although downstream target genes and the regulatory mechanism of PRC2 are well understood, much less is known about the significance of posttranslational regulation of PRC2 protein activity. Here, we show the posttranslational regulation of CURLY LEAF (CLF) SET-domain polycomb group (PcG) protein by the F-box protein, UPWARD CURLY LEAF1 (UCL1). Overexpression of UCL1 generates mutant phenotypes similar to those observed in plants with a loss-of-function mutation in the CLF gene. Leaf curling and early flowering phenotypes of UCL1 overexpression mutants, like clf mutants, are rescued by mutations in the AGAMOUS and FLOWERING LOCUS T genes, which is consistent with UCL1 and CLF functioning in the same genetic pathway. Overexpression of UCL1 reduces the level of CLF protein and alters expression and H3K27 methylation of CLF-target genes in transgenic plants, suggesting that UCL1 negatively regulates CLF. Interaction of UCL1 with CLF was detected in plant nuclei and in the yeast two-hybrid system. The UCL1 F-box binds in vivo to components of the E3 ligase complex, which ubiquitylate proteins that are subsequently degraded via the ubiquitin-26S proteasome pathway. Taken together, these results demonstrate the posttranslational regulation of the CLF SET-domain PcG activity by the UCL1 F-box protein in the E3 ligase complex.
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129
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Lozano-Durán R, Rosas-Díaz T, Gusmaroli G, Luna AP, Taconnat L, Deng XW, Bejarano ER. Geminiviruses subvert ubiquitination by altering CSN-mediated derubylation of SCF E3 ligase complexes and inhibit jasmonate signaling in Arabidopsis thaliana. THE PLANT CELL 2011; 23:1014-32. [PMID: 21441437 PMCID: PMC3082251 DOI: 10.1105/tpc.110.080267] [Citation(s) in RCA: 155] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2010] [Revised: 02/15/2011] [Accepted: 03/04/2011] [Indexed: 05/19/2023]
Abstract
Viruses must create a suitable cell environment and elude defense mechanisms, which likely involves interactions with host proteins and subsequent interference with or usurpation of cellular machinery. Here, we describe a novel strategy used by plant DNA viruses (Geminiviruses) to redirect ubiquitination by interfering with the activity of the CSN (COP9 signalosome) complex. We show that geminiviral C2 protein interacts with CSN5, and its expression in transgenic plants compromises CSN activity on CUL1. Several responses regulated by the CUL1-based SCF ubiquitin E3 ligases (including responses to jasmonates, auxins, gibberellins, ethylene, and abscisic acid) are altered in these plants. Impairment of SCF function is confirmed by stabilization of yellow fluorescent protein-GAI, a substrate of the SCF(SLY1). Transcriptomic analysis of these transgenic plants highlights the response to jasmonates as the main SCF-dependent process affected by C2. Exogenous jasmonate treatment of Arabidopsis thaliana plants disrupts geminivirus infection, suggesting that the suppression of the jasmonate response might be crucial for infection. Our findings suggest that C2 affects the activity of SCFs, most likely through interference with the CSN. As SCFs are key regulators of many cellular processes, the capability of viruses to selectively interfere with or hijack the activity of these complexes might define a novel and powerful strategy in viral infections.
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Affiliation(s)
- Rosa Lozano-Durán
- Instituto de Hortofruticultura Subtropical y Mediterranea, Universidad de Málaga-Consejo Superior de Investigaciones Científicas, Departamento de Biología Celular y Genética, Universidad de Málaga, Campus de Teatinos, E-29071 Malaga, Spain
| | - Tabata Rosas-Díaz
- Instituto de Hortofruticultura Subtropical y Mediterranea, Universidad de Málaga-Consejo Superior de Investigaciones Científicas, Departamento de Biología Celular y Genética, Universidad de Málaga, Campus de Teatinos, E-29071 Malaga, Spain
| | - Giuliana Gusmaroli
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520-8104
| | - Ana P. Luna
- Instituto de Hortofruticultura Subtropical y Mediterranea, Universidad de Málaga-Consejo Superior de Investigaciones Científicas, Departamento de Biología Celular y Genética, Universidad de Málaga, Campus de Teatinos, E-29071 Malaga, Spain
| | - Ludivine Taconnat
- Unité Mixte de Recherche, Institut National de la Recherche Agronomique 1165, Centre National de la Recherche Scientifique 8114, UEVE, 91057 Evry, France
| | - Xing Wang Deng
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520-8104
| | - Eduardo R. Bejarano
- Instituto de Hortofruticultura Subtropical y Mediterranea, Universidad de Málaga-Consejo Superior de Investigaciones Científicas, Departamento de Biología Celular y Genética, Universidad de Málaga, Campus de Teatinos, E-29071 Malaga, Spain
- Address correspondence to
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130
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Kanke M, Nishimura K, Kanemaki M, Kakimoto T, Takahashi TS, Nakagawa T, Masukata H. Auxin-inducible protein depletion system in fission yeast. BMC Cell Biol 2011; 12:8. [PMID: 21314938 PMCID: PMC3048574 DOI: 10.1186/1471-2121-12-8] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2010] [Accepted: 02/11/2011] [Indexed: 01/03/2023] Open
Abstract
Background Inducible inactivation of a protein is a powerful approach for analysis of its function within cells. Fission yeast is a useful model for studying the fundamental mechanisms such as chromosome maintenance and cell cycle. However, previously published strategies for protein-depletion are successful only for some proteins in some specific conditions and still do not achieve efficient depletion to cause acute phenotypes such as immediate cell cycle arrest. The aim of this work was to construct a useful and powerful protein-depletion system in Shizosaccaromyces pombe. Results We constructed an auxin-inducible degron (AID) system, which utilizes auxin-dependent poly-ubiquitination of Aux/IAA proteins by SCFTIR1 in plants, in fission yeast. Although expression of a plant F-box protein, TIR1, decreased Mcm4-aid, a component of the MCM complex essential for DNA replication tagged with Aux/IAA peptide, depletion did not result in an evident growth defect. We successfully improved degradation efficiency of Mcm4-aid by fusion of TIR1 with fission yeast Skp1, a conserved F-box-interacting component of SCF (improved-AID system; i-AID), and the cells showed severe defect in growth. The i-AID system induced degradation of Mcm4-aid in the chromatin-bound MCM complex as well as those in soluble fractions. The i-AID system in conjunction with transcription repression (off-AID system), we achieved more efficient depletion of other proteins including Pol1 and Cdc45, causing early S phase arrest. Conclusion Improvement of the AID system allowed us to construct conditional null mutants of S. pombe. We propose that the off-AID system is the powerful method for in vivo protein-depletion in fission yeast.
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Affiliation(s)
- Mai Kanke
- Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
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131
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Activity-dormancy transition in the cambial meristem involves stage-specific modulation of auxin response in hybrid aspen. Proc Natl Acad Sci U S A 2011; 108:3418-23. [PMID: 21289280 DOI: 10.1073/pnas.1011506108] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The molecular basis of short-day-induced growth cessation and dormancy in the meristems of perennial plants (e.g., forest trees growing in temperate and high-latitude regions) is poorly understood. Using global transcript profiling, we show distinct stage-specific alterations in auxin responsiveness of the transcriptome in the stem tissues during short-day-induced growth cessation and both the transition to and establishment of dormancy in the cambial meristem of hybrid aspen trees. This stage-specific modulation of auxin signaling appears to be controlled via distinct mechanisms. Whereas the induction of growth cessation in the cambium could involve induction of repressor auxin response factors (ARFs) and down-regulation of activator ARFs, dormancy is associated with perturbation of the activity of the SKP-Cullin-F-box(TIR) (SCF(TIR)) complex, leading to potential stabilization of repressor auxin (AUX)/indole-3-acetic acid (IAA) proteins. Although the role of hormones, such as abscisic acid (ABA) and gibberellic acid (GA), in growth cessation and dormancy is well established, our data now implicate auxin in this process. Importantly, in contrast to most developmental processes in which regulation by auxin involves changes in cellular auxin contents, day-length-regulated induction of cambial growth cessation and dormancy involves changes in auxin responses rather than auxin content.
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132
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Bishopp A, Benková E, Helariutta Y. Sending mixed messages: auxin-cytokinin crosstalk in roots. CURRENT OPINION IN PLANT BIOLOGY 2011; 14:10-6. [PMID: 20926335 DOI: 10.1016/j.pbi.2010.08.014] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2010] [Accepted: 08/30/2010] [Indexed: 05/20/2023]
Abstract
Despite their relatively simple appearance, roots are incredibly complex organs that are highly adapted to differing environments. Many aspects of root development are co-ordinated by subtle spatial differences in the concentrations of the phytohormones auxin and cytokinin. Events from the formation of a root during embryogenesis to the determination of the network of lateral roots are controlled by interactions between these hormones. Recently, interactions have been defined where auxin signaling promotes the expression of cytokinin signaling inhibitors, cytokinin signaling promotes the expression of auxin signaling inhibitors and finally where cytokinin signaling regulates the complex network of auxin transport proteins to position zones of high auxin signaling. We are witnessing a period of discovery in which we are beginning to understand how these hormonal pathways communicate to regulate root formation.
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Affiliation(s)
- Anthony Bishopp
- Institute of Biotechnology/Department of Biosciences, University of Helsinki, FIN-00014, Finland
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133
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Nibau C, Gibbs DJ, Bunting KA, Moody LA, Smiles EJ, Tubby JA, Bradshaw SJ, Coates JC. ARABIDILLO proteins have a novel and conserved domain structure important for the regulation of their stability. PLANT MOLECULAR BIOLOGY 2011; 75:77-92. [PMID: 21052782 DOI: 10.1007/s11103-010-9709-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Accepted: 10/20/2010] [Indexed: 05/10/2023]
Abstract
ARABIDILLO proteins are F-box-Armadillo (ARM) proteins that regulate root branching in Arabidopsis. Many F-box proteins in plants, yeast and mammals are unstable. In plants, the mechanism for this instability has not been fully investigated. Here, we show that a conserved family of plant ARABIDILLO-related proteins has a unique domain structure consisting of an F-box and leucine-rich repeats (LRRs) followed by ARM-repeats. The LRRs are similar to those found in other plant and animal F-box proteins, including cell cycle proteins and hormone receptors. We demonstrate that the LRRs are required for ARABIDILLO1 function in vivo. ARABIDILLO1 protein is unstable: we show that ARABIDILLO1 protein is associated with ubiquitin and is turned over by the proteasome. Both the F-box and LRR regions of ARABIDILLO1 appear to enable this turnover to occur. Application of known lateral root-regulating signals has no effect on ARABIDILLO1 stability. In addition, plants that lack or overexpress ARABIDILLO proteins respond normally to known lateral root-regulating signals. Thus, we suggest that the signal(s) regulating ARABIDILLO stability in vivo may be either highly specific or novel. The structural conservation between ARABIDILLOs and other plant and animal F-box proteins suggests that the stability of other F-box proteins may be controlled by similar mechanisms.
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Affiliation(s)
- Cândida Nibau
- School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK
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134
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Abstract
The posttranslational addition of ubiquitin (Ub) helps control the half-life, localization, and action of many intracellular plant proteins. A primary function is the degradation of ubiquitylated proteins by the 26S proteasome, which in turn plays important housekeeping and regulatory roles by removing aberrant polypeptides and various normal short-lived regulators. Strikingly, both genetic and genomic studies reveal that Ub conjugation is extraordinarily complex in plants, with more than 1500 Ub-protein ligases (or E3s) possible that could direct the final transfer of the Ub moiety to an equally large number of targets. The cullin-RING ligases (CRLs) are a highly polymorphic E3 collection composed of a cullin backbone onto which binds carriers of activated Ub and a diverse assortment of adaptors that recruit appropriate substrates for ubiquitylation. Here, we review our current understanding of the organization and structure of CRLs in plants and their dynamics, substrates, potential functions, and evolution. The importance of CRLs is exemplified by their ability to serve as sensors of hormones and light; their essential participation in various signaling pathways; their control of the cell cycle, transcription, the stress response, self-incompatibility, and pathogen defense; and their dramatically divergent evolutionary histories in many plant lineages. Given both their organizational complexities and their critical influences, CRLs likely impact most, if not all, aspects of plant biology.
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Affiliation(s)
- Zhihua Hua
- Department of Genetics, University of Wisconsin, Madison, Wisconsin 53706-1574, USA.
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135
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Del Bianco M, Kepinski S. Context, specificity, and self-organization in auxin response. Cold Spring Harb Perspect Biol 2011; 3:a001578. [PMID: 21047914 DOI: 10.1101/cshperspect.a001578] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Auxin is a simple molecule with a remarkable ability to control plant growth, differentiation, and morphogenesis. The mechanistic basis for this versatility appears to stem from the highly complex nature of the networks regulating auxin metabolism, transport and response. These heavily feedback-regulated and inter-dependent mechanisms are complicated in structure and complex in operation giving rise to a system with self-organizing properties capable of generating highly context-specific responses to auxin as a single, generic signal.
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Affiliation(s)
- Marta Del Bianco
- University of Leeds, Faculty of Biological Sciences, Leeds, LS2 9JT, United Kingdom
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136
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Uppalapati SR, Ishiga Y, Ryu CM, Ishiga T, Wang K, Noël LD, Parker JE, Mysore KS. SGT1 contributes to coronatine signaling and Pseudomonas syringae pv. tomato disease symptom development in tomato and Arabidopsis. THE NEW PHYTOLOGIST 2011; 189:83-93. [PMID: 20854394 DOI: 10.1111/j.1469-8137.2010.03470.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
• Pseudomonas syringae pv. tomato DC3000 (Pst DC3000) causes an economically important bacterial speck disease on tomato and produces symptoms with necrotic lesions surrounded by chlorosis. The chlorosis is mainly attributed to a jasmonic acid (JA)-isoleucine analogue, coronatine (COR), produced by Pst DC3000. However, the molecular processes underlying lesion development and COR-induced chlorosis are poorly understood. • In this study, we took advantage of a chlorotic phenotype elicited by COR on Nicotiana benthamiana leaves and virus-induced gene silencing (VIGS) as a rapid reverse genetic screening tool and identified a role for SGT1 (suppressor of G2 allele of skp1) in COR-induced chlorosis. • Silencing of SGT1 in tomato resulted in reduction of disease-associated symptoms (cell death and chlorosis), suggesting a molecular connection between COR-induced chlorosis and cell death. In Arabidopsis, AtSGT1b but not AtSGT1a was required for COR responses, including root growth inhibition and Pst DC3000 symptom (water soaked lesion) development. Notably, overexpression of AtSGT1b did not alter Pst DC3000 symptoms or sensitivity to COR. • Taken together, our results demonstrate that SGT1/SGT1b is required for COR-induced chlorosis and subsequent necrotic disease development in tomato and Arabidopsis. SGT1 is therefore a component of the COR/JA-mediated signal transduction pathway.
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137
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Abstract
The history of plant biology is inexorably intertwined with the conception and discovery of auxin, followed by the many decades of research to comprehend its action during growth and development. Growth responses to auxin are complex and require the coordination of auxin production, transport, and perception. In this overview of past auxin research, we limit our discourse to the mechanism of auxin action. We attempt to trace the almost epic voyage from the birth of the hormonal concept in plants to the recent crystallographic studies that resolved the TIR1-auxin receptor complex, the first structural model of a plant hormone receptor. The century-long endeavor is a beautiful illustration of the power of scientific reasoning and human intuition, but it also brings to light the fact that decisive progress is made when new technologies emerge and disciplines unite.
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Affiliation(s)
- Steffen Abel
- Department of Molecular Signal Processing, Leibniz-Institute of Plant Biochemistry, D-06120 Halle (Saale), Germany.
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138
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Yang XY, Chen WP, Rendahl AK, Hegeman AD, Gray WM, Cohen JD. Measuring the turnover rates of Arabidopsis proteins using deuterium oxide: an auxin signaling case study. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 63:680-695. [PMID: 20525007 DOI: 10.1111/j.1365-313x.2010.04266.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Rapid environmental responses in plants rely on endogenous signaling mechanisms, which in many cases are mediated by changes in protein turnover rates. It is therefore necessary to develop methods for measuring protein dynamics that monitor large sets of plant proteins to begin to apply a systems biology approach to the study of plant behavior. The use of stable isotope labeling strategies that are adaptable to proteomic methods is particularly attractive for this purpose. Here, we explore one example of such methods that is particularly suitable for plants at the seedling stage, where measurement of amino acid and protein turnover rates is accomplished using a heavy water labeling strategy. The method is backed by microarray evaluation to define its feasibility for specific experimental approaches, and the CULLIN-ASSOCIATED AND NEDDYLATION DISSOCIATED 1 (CAND1) and TRANSPORT INHIBITOR RESPONSE 1 (TIR1) proteins are used to illustrate the potential utility in understanding hormonal signaling regulation. These studies provide insight not only into the potential utility of the method, but also address possible areas of concern regarding the use of heavy water labeling during plant growth. These considerations suggest a prescription for specific experimental designs that minimize interference resulting from the induction of treatment-specific gene expression in the results obtained.
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Affiliation(s)
- Xiao-Yuan Yang
- Department of Plant Biology, University of Minnesota, St. Paul, MN 55108, USA
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139
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Calderon-Villalobos LI, Tan X, Zheng N, Estelle M. Auxin perception--structural insights. Cold Spring Harb Perspect Biol 2010; 2:a005546. [PMID: 20504967 DOI: 10.1101/cshperspect.a005546] [Citation(s) in RCA: 117] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The identity of the auxin receptor(s) and the mechanism of auxin perception has been a subject of intense interest since the discovery of auxin almost a century ago. The development of genetic approaches to the study of plant hormone signaling led to the discovery that auxin acts by promoting degradation of transcriptional repressors called Aux/IAA proteins. This process requires a ubiquitin protein ligase (E3) called SCF(TIR1) and related SCF complexes. Surprisingly, auxin works by directly binding to TIR1, the F-box protein subunit of this SCF. Structural studies demonstrate that auxin acts like a "molecular glue," to stabilize the interaction between TIR1 and the Aux/IAA substrate. These exciting results solve an old problem in plant biology and reveal new mechanisms for E3 regulation and hormone perception.
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140
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Knepper C, Day B. From perception to activation: the molecular-genetic and biochemical landscape of disease resistance signaling in plants. THE ARABIDOPSIS BOOK 2010; 8:e012. [PMID: 22303251 PMCID: PMC3244959 DOI: 10.1199/tab.0124] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
More than 60 years ago, H.H. Flor proposed the "Gene-for-Gene" hypothesis, which described the genetic relationship between host plants and pathogens. In the decades that followed Flor's seminal work, our understanding of the plant-pathogen interaction has evolved into a sophisticated model, detailing the molecular genetic and biochemical processes that control host-range, disease resistance signaling and susceptibility. The interaction between plants and microbes is an intimate exchange of signals that has evolved for millennia, resulting in the modification and adaptation of pathogen virulence strategies and host recognition elements. In total, plants have evolved mechanisms to combat the ever-changing landscape of biotic interactions bombarding their environment, while in parallel, plant pathogens have co-evolved mechanisms to sense and adapt to these changes. On average, the typical plant is susceptible to attack by dozens of microbial pathogens, yet in most cases, remains resistant to many of these challenges. The sum of research in our field has revealed that these interactions are regulated by multiple layers of intimately linked signaling networks. As an evolved model of Flor's initial observations, the current paradigm in host-pathogen interactions is that pathogen effector molecules, in large part, drive the recognition, activation and subsequent physiological responses in plants that give rise to resistance and susceptibility. In this Chapter, we will discuss our current understanding of the association between plants and microbial pathogens, detailing the pressures placed on both host and microbe to either maintain disease resistance, or induce susceptibility and disease. From recognition to transcriptional reprogramming, we will review current data and literature that has advanced the classical model of the Gene-for-Gene hypothesis to our current understanding of basal and effector triggered immunity.
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Affiliation(s)
- Caleb Knepper
- Michigan State University. Program in Genetics. East Lansing, MI 48824. USA
- Michigan State University. Department of Energy Plant Research Laboratory. East Lansing, MI 48824. USA
| | - Brad Day
- Michigan State University. Program in Genetics. East Lansing, MI 48824. USA
- Michigan State University. Department of Plant Pathology. East Lansing, MI 48824. USA
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141
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Zhou Y, Ni M. SHORT HYPOCOTYL UNDER BLUE1 truncations and mutations alter its association with a signaling protein complex in Arabidopsis. THE PLANT CELL 2010; 22:703-15. [PMID: 20354198 PMCID: PMC2861450 DOI: 10.1105/tpc.109.071407] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Revised: 02/25/2010] [Accepted: 03/17/2010] [Indexed: 05/20/2023]
Abstract
Higher plants monitor their ambient light signals through red/far-red absorbing phytochromes and blue/UV-A light absorbing cryptochromes. Subsequent signaling cascades alter gene expression and initiate morphogenic responses. We previously isolated SHORT HYPOCOTYL UNDER BLUE1 (SHB1), a putative transcriptional coactivator in light signaling. SHB1 is homologous to the SYG1 protein family and contains an N-terminal SPX domain and a C-terminal EXS domain. Overaccumulation of the SPX domain caused a long hypocotyl phenotype similar to that of shb1-D under red, far-red, or blue light. By contrast, overaccumulation of the C-terminal EXS domain led to a short hypocotyl phenotype similar to that of shb1 under blue light. The N-terminal SPX domain was associated with a smaller protein complex than the native protein complex associated with endogenous SHB1. By contrast, the EXS domain was associated with a slightly smaller protein complex than the native protein complex, but it largely displaced endogenous SHB1 from its native protein complex. In addition, all six missense mutations that we identified from a suppressor screen were clustered within or close to the SPX domain, and these mutations impaired the assembly of the SHB1-containing protein complex. We propose that both SPX and EXS domains likely anchor SHB1 to a protein complex, and the SPX domain is critical for SHB1 signaling.
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Affiliation(s)
| | - Min Ni
- Department of Plant Biology, University of Minnesota, St. Paul, Minnesota 55108
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142
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Santner A, Estelle M. The ubiquitin-proteasome system regulates plant hormone signaling. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 61:1029-40. [PMID: 20409276 PMCID: PMC3066055 DOI: 10.1111/j.1365-313x.2010.04112.x] [Citation(s) in RCA: 265] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Plants utilize the ubiquitin-proteasome system (UPS) to modulate nearly every aspect of growth and development. Ubiquitin is covalently attached to target proteins through the action of three enzymes known as E1, E2, and E3. The ultimate outcome of this post-translational modification depends on the nature of the ubiquitin linkage and the extent of polyubiquitination. In most cases, ubiquitination results in degradation of the target protein in the 26S proteasome. During the last 10 years it has become clear that the UPS plays a prominent regulatory role in hormone biology. E3 ubiquitin ligases in particular actively participate in hormone perception, de-repression of hormone signaling pathways, degradation of hormone specific transcription factors, and regulation of hormone biosynthesis. It is certain that additional functions will be discovered as more of the nearly 1200 potential E3s in plants are elucidated.
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Affiliation(s)
- Aaron Santner
- Molecular Kinetics, Inc., 6201 La Pas Trail, Suite 160, Indianapolis, IN 46268, USA
| | - Mark Estelle
- University of California San Diego, Section of Cell and Developmental Biology, 9500 Gilman Drive, La Jolla, CA 9209, USA
- For correspondence (fax +858 534 7108; )
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143
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Dohmann EMN, Nill C, Schwechheimer C. DELLA proteins restrain germination and elongation growth in Arabidopsis thaliana COP9 signalosome mutants. Eur J Cell Biol 2010; 89:163-8. [PMID: 20083325 DOI: 10.1016/j.ejcb.2009.12.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
The COP9 signalosome (CSN) is an evolutionarily conserved multiprotein complex with an essential role in the development of higher eukaryotes. CSN deconjugates the ubiquitin-related modifier NEDD8 from the cullin subunit of cullin-RING type E3 ubiquitin ligases (CRLs), and CSN-mediated cullin deneddylation is required for full CRL activity. Although several plant E3 CRL functions have been shown to be compromised in Arabidopsis csn mutants, none of these functions have so far been shown to limit growth in these mutants. Here, we examine the role of CSN in the context of the E3 ubiquitin ligase SCF(SLEEPY1 (SLY1)), which promotes gibberellic acid (GA)-dependent responses in Arabidopsis thaliana. We show that csn mutants are impaired in GA- and SCF(SLY1)-dependent germination and elongation growth, and we show that these defects correlate with an accumulation and reduced turnover of an SCF(SLY1)-degradation target, the DELLA protein REPRESSOR-OF-ga1-3 (RGA). Genetic interaction studies between csn mutants and loss-of-function alleles of RGA and its functional homologue GIBBERELLIC ACID INSENSITIVE (GAI) further reveal that RGA and GAI repress defects of germination in strong csn mutants. In addition, we find that these two DELLA proteins are largely responsible for the elongation defects of a weak csn5 mutant allele. We thus conclude that an impairment of SCF(SLY1) is at least in part causative for the germination and elongation defects of csn mutants, and suggest that DELLA proteins are major growth repressors in these mutants.
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Affiliation(s)
- Esther Mirjam Natascha Dohmann
- Department of Developmental Genetics, Center for Plant Molecular Biology, Tübingen University, Auf der Morgenstelle 5, 72076 Tübingen, Germany
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Abstract
Plant hormones control most aspects of the plant life cycle by regulating genome expression. Expression of auxin-responsive genes involves interactions among auxin-responsive DNA sequence elements, transcription factors and trans-acting transcriptional repressors. Transcriptional output from these auxin signaling complexes is regulated by proteasome-mediated degradation that is triggered by interaction with auxin receptor-E3 ubiquitin ligases such SCF(TIR1). Auxin signaling components are conserved throughout land plant evolution and have proliferated and specialized to control specific developmental processes.
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Affiliation(s)
- Elisabeth J Chapman
- Division of Biology, University of California, San Diego, La Jolla, California 92093-0116, USA.
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145
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Felten J, Kohler A, Morin E, Bhalerao RP, Palme K, Martin F, Ditengou FA, Legué V. The ectomycorrhizal fungus Laccaria bicolor stimulates lateral root formation in poplar and Arabidopsis through auxin transport and signaling. PLANT PHYSIOLOGY 2009; 151:1991-2005. [PMID: 19854859 PMCID: PMC2785963 DOI: 10.1104/pp.109.147231] [Citation(s) in RCA: 149] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2009] [Accepted: 10/16/2009] [Indexed: 05/18/2023]
Abstract
The early phase of the interaction between tree roots and ectomycorrhizal fungi, prior to symbiosis establishment, is accompanied by a stimulation of lateral root (LR) development. We aimed to identify gene networks that regulate LR development during the early signal exchanges between poplar (Populus tremula x Populus alba) and the ectomycorrhizal fungus Laccaria bicolor with a focus on auxin transport and signaling pathways. Our data demonstrated that increased LR development in poplar and Arabidopsis (Arabidopsis thaliana) interacting with L. bicolor is not dependent on the ability of the plant to form ectomycorrhizae. LR stimulation paralleled an increase in auxin accumulation at root apices. Blocking plant polar auxin transport with 1-naphthylphthalamic acid inhibited LR development and auxin accumulation. An oligoarray-based transcript profile of poplar roots exposed to molecules released by L. bicolor revealed the differential expression of 2,945 genes, including several components of polar auxin transport (PtaPIN and PtaAUX genes), auxin conjugation (PtaGH3 genes), and auxin signaling (PtaIAA genes). Transcripts of PtaPIN9, the homolog of Arabidopsis AtPIN2, and several PtaIAAs accumulated specifically during the early interaction phase. Expression of these rapidly induced genes was repressed by 1-naphthylphthalamic acid. Accordingly, LR stimulation upon contact with L. bicolor in Arabidopsis transgenic plants defective in homologs of these genes was decreased or absent. Furthermore, in Arabidopsis pin2, the root apical auxin increase during contact with the fungus was modified. We propose a model in which fungus-induced auxin accumulation at the root apex stimulates LR formation through a mechanism involving PtaPIN9-dependent auxin redistribution together with PtaIAA-based auxin signaling.
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Affiliation(s)
| | | | | | | | | | | | | | - Valérie Legué
- INRA and Nancy Université, UMR INRA/Nancy Université 1136 Interactions Arbres/Micro-organismes, Institut Fédératif de Recherche 110 “Genomique, Ecophysiologie, et Ecologie Fonctionnelles,” INRA Nancy, F–54280 Champenoux, France (J.F., A.K., E.M., F.M., V.L.); Umeå Plant Science Center, Department of Plant Physiology, Umeå University, SE–901 87 Umeå, Sweden (R.P.B.); and Institutes of Biology II and Biology III, Faculty of Biology, Albert-Ludwigs-Universität Freiburg, D–79104 Freiburg, Germany (K.P., F.A.D.)
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146
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Abstract
BACKGROUND Cullins are proteins involved in ubiquitination through their participation in multisubunit ubiquitin ligase complexes. In this study, I use comparative genomic data to establish the pattern of emergence and diversification of cullins in eukaryotes. RESULTS The available data indicate that there were three cullin genes before the unikont/bikont split, which I have called Culalpha, Culbeta and Culgamma. Fungal species have quite strictly conserved these three ancestral genes, with only occasional lineage-specific duplications. On the contrary, several additional genes appeared in the animal or plant lineages. For example, the human genes Cul1, Cul2, Cul5, Cul7 and Parc all derive from the ancestral Culalpha gene. These results, together with the available functional data, suggest that three different types of ubiquitin ligase cullin-containing complexes were already present in early eukaryotic evolution: 1) SCF-like complexes with Culalpha proteins; 2) Culbeta/BTB complexes; and, 3) Complexes containing Culgamma and DDB1-like proteins. Complexes containing elongins have arisen more recently and perhaps twice independently in animals and fungi. CONCLUSION Most of the known types of cullin-containing ubiquitin ligase complexes are ancient. The available data suggest that, since the origin of eukaryotes, complex diversity has been mostly generated by combining closely related subunits, while radical innovations, giving rise to novel types of complexes, have been scarce. However, several protist groups not examined so far contain highly divergent cullins, indicating that additional types of complexes may exist.
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Affiliation(s)
- Ignacio Marín
- Instituto de Biomedicina de Valencia, Consejo Superior de Investigaciones Científicas, Valencia, Spain.
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147
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An auxin-based degron system for the rapid depletion of proteins in nonplant cells. Nat Methods 2009; 6:917-22. [PMID: 19915560 DOI: 10.1038/nmeth.1401] [Citation(s) in RCA: 1115] [Impact Index Per Article: 74.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2009] [Accepted: 10/02/2009] [Indexed: 12/21/2022]
Abstract
Plants have evolved a unique system in which the plant hormone auxin directly induces rapid degradation of the AUX/IAA family of transcription repressors by a specific form of the SCF E3 ubiquitin ligase. Other eukaryotes lack the auxin response but share the SCF degradation pathway, allowing us to transplant the auxin-inducible degron (AID) system into nonplant cells and use a small molecule to conditionally control protein stability. The AID system allowed rapid and reversible degradation of target proteins in response to auxin and enabled us to generate efficient conditional mutants of essential proteins in yeast as well as cell lines derived from chicken, mouse, hamster, monkey and human cells, thus offering a powerful tool to control protein expression and study protein function.
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148
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Chung HS, Niu Y, Browse J, Howe GA. Top hits in contemporary JAZ: an update on jasmonate signaling. PHYTOCHEMISTRY 2009; 70:1547-59. [PMID: 19800644 PMCID: PMC3271379 DOI: 10.1016/j.phytochem.2009.08.022] [Citation(s) in RCA: 132] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2009] [Revised: 08/06/2009] [Accepted: 08/24/2009] [Indexed: 05/19/2023]
Abstract
The phytohormone jasmonate (JA) regulates a wide range of growth, developmental, and defense-related processes during the plant life cycle. Identification of the JAZ family of proteins that repress JA responses has facilitated rapid progress in understanding how this lipid-derived hormone controls gene expression. Recent analysis of JAZ proteins has provided insight into the nature of the JA receptor, the chemical specificity of signal perception, and cross-talk between JA and other hormone response pathways. Functional diversification of JAZ proteins by alternative splicing, together with the ability of JAZ proteins to homo- and heterodimerize, provide mechanisms to enhance combinatorial diversity and versatility in gene regulation by JA.
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Affiliation(s)
- Hoo Sun Chung
- DOE Plant Research Laboratory, Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824-1312
| | - Yajie Niu
- Institute of Biological Chemistry, Washington State University, Pullman, WA 99164-6340
| | - John Browse
- Institute of Biological Chemistry, Washington State University, Pullman, WA 99164-6340
| | - Gregg A. Howe
- DOE Plant Research Laboratory, Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824-1312
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149
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Niu Y, Wu GZ, Ye R, Lin WH, Shi QM, Xue LJ, Xu XD, Li Y, Du YG, Xue HW. Global analysis of gene expression profiles in Brassica napus developing seeds reveals a conserved lipid metabolism regulation with Arabidopsis thaliana. MOLECULAR PLANT 2009; 2:1107-22. [PMID: 19825684 DOI: 10.1093/mp/ssp042] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
In order to study Brassica napus fatty acid (FA) metabolism and relevant regulatory networks, a systematic identification of fatty acid (FA) biosynthesis-related genes was conducted. Following gene identification, gene expression profiles during B. napus seed development and FA metabolism were performed by cDNA chip hybridization (>8000 EST clones from seed). The results showed that FA biosynthesis and regulation, and carbon flux, were conserved between B. napus and Arabidopsis. However, a more critical role of starch metabolism was detected for B. napus seed FA metabolism and storage-component accumulation when compared with Arabidopsis. In addition, a crucial stage for the transition of seed-to-sink tissue was 17-21 d after flowering (DAF), whereas FA biosynthesis-related genes were highly expressed primarily at 21 DAF. Hormone (auxin and jasmonate) signaling is found to be important for FA metabolism. This study helps to reveal the global regulatory network of FA metabolism in developing B. napus seeds.
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Affiliation(s)
- Ya Niu
- National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Science (SIBS), Chinese Academy of Sciences, 300 Fenglin Road, 200032 Shanghai, China
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150
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Chang LC, Guo CL, Lin YS, Fu H, Wang CS, Jauh GY. Pollen-Specific SKP1-Like Proteins are Components of Functional SCF Complexes and Essential for Lily Pollen Tube Elongation. ACTA ACUST UNITED AC 2009; 50:1558-72. [DOI: 10.1093/pcp/pcp100] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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