Brassinosteroids Regulate Grain Filling in Rice

Wu, Chuanyin; Trieu, Anthony; Radhakrishnan, Parthiban; Kwok, Shing F.; Harris, Sam; Zhang, Ke; Wang, Jiulin; Wan, Jianmin; Zhai, Huqu; Takatsuto, Suguru; Matsumoto, Shogo; Fujioka, Shozo; Feldmann, Kenneth A.; Pennell, Roger I.

doi:10.1105/tpc.107.055087

Cited by 340 publications

(278 citation statements)

References 69 publications

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“…Furthermore, many studies have shown important roles of BR in specific developmental processes. For example, overexpression of BR biosynthetic gene increases grain filling and rice yield (Wu et al, 2008). One of the most sensitive BR responses in rice is lamina joint inclination (Wada et al, 1981).…”

Section: Introductionmentioning

confidence: 99%

Antagonistic HLH/bHLH Transcription Factors Mediate Brassinosteroid Regulation of Cell Elongation and Plant Development in Rice andArabidopsis

et al. 2009

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In rice (Oryza sativa), brassinosteroids (BRs) induce cell elongation at the adaxial side of the lamina joint to promote leaf bending. We identified a rice mutant (ili1-D) showing an increased lamina inclination phenotype similar to that caused by BR treatment. The ili1-D mutant overexpresses an HLH protein homologous to Arabidopsis thaliana Paclobutrazol Resistance1 (PRE1) and the human Inhibitor of DNA binding proteins. Overexpression and RNA interference suppression of ILI1 increase and reduce, respectively, rice laminar inclination, confirming a positive role of ILI1 in leaf bending. ILI1 and PRE1 interact with basic helix-loop-helix (bHLH) protein IBH1 (ILI1 binding bHLH), whose overexpression causes erect leaf in rice and dwarfism in Arabidopsis. Overexpression of ILI1 or PRE1 increases cell elongation and suppresses dwarf phenotypes caused by overexpression of IBH1 in Arabidopsis. Thus, ILI1 and PRE1 may inactivate inhibitory bHLH transcription factors through heterodimerization. BR increases the RNA levels of ILI1 and PRE1 but represses IBH1 through the transcription factor BZR1. The spatial and temporal expression patterns support roles of ILI1 in laminar joint bending and PRE1/At IBH1 in the transition from growth of young organs to growth arrest. These results demonstrate a conserved mechanism of BR regulation of plant development through a pair of antagonizing HLH/bHLH transcription factors that act downstream of BZR1 in Arabidopsis and rice.

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Section: Introductionmentioning

confidence: 99%

Antagonistic HLH/bHLH Transcription Factors Mediate Brassinosteroid Regulation of Cell Elongation and Plant Development in Rice andArabidopsis

et al. 2009

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“…In addition, the BR signaling-defective mutant d61-7, the weakest mutant of rice BRASSINOSTEROID INSENSITIVE1 (OsBRI1, a protein kinase severing as rice BR receptor), and transgenic rice plants with suppressed expression of OsBZR1 (a transcription factor involved in BR signaling pathway), showed erect leaves [13][14][15]. Conversely, transgenic rice plants overexpressing sterol C-22 hydroxylase, which catalyzes a rate-limiting step in BR biosynthesis, showed a slightly sprawling phenotype with increased leaf angles [16,17]. These results indicate the critical effects of BR, both biosynthesis and signaling, in regulating leaf inclination.…”

Section: Introductionmentioning

confidence: 99%

Rice leaf inclination2, a VIN3-like protein, regulates leaf angle through modulating cell division of the collar

et al. 2010

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As an important agronomic trait, inclination of leaves is crucial for crop architecture and grain yields. To understand the molecular mechanism controlling rice leaf angles, one rice leaf inclination2 (lc2, three alleles) mutant was identified and functionally characterized. Compared to wild-type plants, lc2 mutants have enlarged leaf angles due to increased cell division in the adaxial epidermis of lamina joint. The LC2 gene was isolated through positional cloning, and encodes a vernalization insensitive 3-like protein. Complementary expression of LC2 reversed the enlarged leaf angles of lc2 plants, confirming its role in controlling leaf inclination. LC2 is mainly expressed in the lamina joint during leaf development, and particularly, is induced by the phytohormones abscisic acid, gibberellic acid, auxin, and brassinosteroids. LC2 is localized in the nucleus and defects of LC2 result in altered expression of cell division and hormone-responsive genes, indicating an important role of LC2 in regulating leaf inclination and mediating hormone effects.

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“…BRs are essential for the elongation of stems and roots and the differentiation of vascular bundles, as well as for senescence, stress response, photomorphogenesis, and tropisms (Mitchell et al, 1970;Clouse, 1996;Li and Chory, 1999;Li et al, 2005). Recently, it has been shown that biomass production and grain yield can be enhanced by controlling the level of endogenous BR in rice (Oryza sativa) plants (Sakamoto et al, 2006;Wu et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

RAV-Like1Maintains Brassinosteroid Homeostasis via the Coordinated Activation ofBRI1and Biosynthetic Genes in Rice

et al. 2010

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Temporal and spatial variation in the levels of and sensitivity to hormones are essential for the development of higher organisms. Traditionally, end-product feedback regulation has been considered as the key mechanism for the achievement of cellular homeostasis. Brassinosteroids (BRs) are plant steroid hormones that are perceived by the cell surface receptor kinase Brassinosteroid Insensitive1. Binding of these hormones to the receptor activates BR signaling and eventually suppresses BR synthesis. This report shows that RAVL1 regulates the expression of the BR receptor. Furthermore, RAVL1 is also required for the expression of the BR biosynthetic genes D2, D11, and BRD1 that are subject to BR negative feedback. Activation by RAVL1 was coordinated via E-box cis-elements in the promoters of the receptor and biosynthetic genes. Also, RAVL1 is necessary for the response of these genes to changes in cellular BR homeostasis. Genetic evidence is presented to strengthen the observation that the primary action of RAVL1 mediates the expression of genes involved in BR signaling and biosynthesis. This study thus describes a regulatory circuit modulating the homeostasis of BR in which RAVL1 ensures the basal activity of both the signaling and the biosynthetic pathways.

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Brassinosteroids Regulate Grain Filling in Rice

Cited by 340 publications

References 69 publications

Antagonistic HLH/bHLH Transcription Factors Mediate Brassinosteroid Regulation of Cell Elongation and Plant Development in Rice andArabidopsis

Antagonistic HLH/bHLH Transcription Factors Mediate Brassinosteroid Regulation of Cell Elongation and Plant Development in Rice andArabidopsis

Rice leaf inclination2, a VIN3-like protein, regulates leaf angle through modulating cell division of the collar

RAV-Like1Maintains Brassinosteroid Homeostasis via the Coordinated Activation ofBRI1and Biosynthetic Genes in Rice

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