Integration of Light- and Brassinosteroid-Signaling Pathways by a GATA Transcription Factor in Arabidopsis

Luo, Xiao; Lin, Wen Hui; Zhu, Shengwei; Zhu, Jiachen; Sun, Yu; Fan, Xi Ying; Cheng, Maojie; Hao, Yaqi; Oh, Eunkyoo; Tian, Miaomiao; Liu, Lijing; Zhang, Ming; Xie, Qi; Chong, Kang; Wang, Wenfei

doi:10.1016/j.devcel.2010.10.023

Cited by 239 publications

(250 citation statements)

References 53 publications

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“…BR promotes rice leaf bending by increasing the expansion of adaxial cells of the laminar joint, through BZR1 regulation of a pair of helix loop helix/basic helix loop helix (HLH/bHLH) factors (42). Such independent mechanisms for a common function support an adaptive value for BR regulation of plant architecture, perhaps to optimally position photosynthetic organs according to environmental or endogenous conditions in addition to coregulation of other photosynthetic aspects such as expression of photosynthetic genes and stomata formation (31,(43)(44)(45). Detailed analyses of the architecture of BR mutants in other species will advance our understanding of the evolution of BR's role in plant architecture.…”

Section: Discussionmentioning

confidence: 99%

Brassinosteroids regulate organ boundary formation in the shoot apical meristem of Arabidopsis

Gendron

Liu

Fan

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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Spatiotemporal control of the formation of organ primordia and organ boundaries from the stem cell niche in the shoot apical meristem (SAM) determines the patterning and architecture of plants, but the underlying signaling mechanisms remain poorly understood. Here we show that brassinosteroids (BRs) play a key role in organ boundary formation by repressing organ boundary identity genes. BR-hypersensitive mutants display organ-fusion phenotypes, whereas BR-insensitive mutants show enhanced organ boundaries. The BR-activated transcription factor BZR1 directly represses the CUP-SHAPED COTYLEDON (CUC) family of organ boundary identity genes. In WT plants, BZR1 accumulates at high levels in the nuclei of central meristem and organ primordia but at a low level in organ boundary cells to allow CUC gene expression. Activation of BR signaling represses CUC gene expression and causes organ fusion phenotypes. This study uncovers a role for BR in the spatiotemporal control of organ boundary formation and morphogenesis in the SAM.hormone | steroid

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Section: Discussionmentioning

confidence: 99%

Brassinosteroids regulate organ boundary formation in the shoot apical meristem of Arabidopsis

Gendron

Liu

Fan

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

165

159

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“…Studies have detailed the mechanisms involved in hypocotyl cell elongation regulated by light, phytohormones, and transcription factors (Wang et al, 2002;Niwa et al, 2009;Luo et al, 2010;Fan et al, 2012). In addition, a recent study showed that pectin-dependent cell wall homeostasis is important for BR regulation of hypocotyl growth (Wolf et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Arabidopsis MICROTUBULE DESTABILIZING PROTEIN40 Is Involved in Brassinosteroid Regulation of Hypocotyl Elongation

et al. 2012

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The brassinosteroid (BR) phytohormones play crucial roles in regulating plant cell growth and morphogenesis, particularly in hypocotyl cell elongation. The microtubule cytoskeleton is also known to participate in the regulation of hypocotyl elongation. However, it is unclear if BR regulation of hypocotyl elongation involves the microtubule cytoskeleton. In this study, we demonstrate that BRs mediate hypocotyl cell elongation by influencing the orientation and stability of cortical microtubules. Further analysis identified the previously undiscovered Arabidopsis thaliana MICROTUBULE DESTABILIZING PROTEIN40 (MDP40) as a positive regulator of hypocotyl cell elongation. BRASSINAZOLE-RESISTANT1, a key transcription factor in the BR signaling pathway, directly targets and upregulates MDP40. Overexpression of MDP40 partially rescued the shorter hypocotyl phenotype in BR-deficient mutant de-etiolated-2 seedlings. Reorientation of the cortical microtubules in the cells of MDP40 RNA interference transgenic lines was less sensitive to BR. These findings demonstrate that MDP40 is a key regulator in BR regulation of cortical microtubule reorientation and mediates hypocotyl growth. This study reveals a mechanism involving BR regulation of microtubules through MDP40 to mediate hypocotyl cell elongation.

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“…This regulation is especially relevant late in the night, when PIF4 transcription is upregulated and the protein is stable. Although BES1 and BZR1 were reported to not be significantly affected by light (Luo et al 2010), the active nonphosphorylated forms of the PIF4 and BES1/BZR1 factors overlap only during late night, BES1/BZR1 coactivator function thus having a relevant role in timing PIF4 transcriptional activity and in rhythmic hypocotyl growth. These results confirm a main function of the PIFs and BES1/BZR1 factors in cell elongation and highlight a role of these two families of bHLH factors as main integrators of light, BR, and GA signals by means of PHYB-and BIN2-induced destabilization and inactive complex formation with the DELLAs.…”

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confidence: 99%

BR-dependent phosphorylation modulates PIF4 transcriptional activity and shapes diurnal hypocotyl growth

et al. 2014

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Signaling by the hormones brassinosteroid (BR) and gibberellin (GA) is critical to normal plant growth and development and is required for hypocotyl elongation in response to dark and elevated temperatures. Active BR signaling is essential for GA promotion of hypocotyl growth and suppresses the dwarf phenotype of GA mutants. Cross-talk between these hormones occurs downstream from the DELLAs, as GA-induced destabilization of these GA signaling repressors is not affected by BRs. Here we show that the light-regulated PIF4 (phytochromeinteracting factor 4) factor is a phosphorylation target of the BR signaling kinase BRASSINOSTEROID-INSENSITIVE 2 (BIN2), which marks this transcriptional regulator for proteasome degradation. Expression of a mutated PIF41A protein lacking a conserved BIN2 phosphorylation consensus causes a severe elongated phenotype and strongly up-regulated expression of the gene targets. However, PIF41A is not able to suppress the dwarf phenotype of the bin2-1 mutant with constitutive activation of this kinase. PIFs were shown to be required for the constitutive BR response of bes1-D and bzr1-1D mutants, these factors acting in an interdependent manner to promote cell elongation. Here, we show that bes1-D seedlings are still repressed by the inhibitor BRZ in the light and that expression of the nonphosphorylatable PIF41A protein makes this mutant fully insensitive to brassinazole (BRZ). PIF41A is preferentially stabilized at dawn, coinciding with the diurnal time of maximal growth. These results uncover a main role of BRs in antagonizing light signaling by inhibiting BIN2-mediated destabilization of the PIF4 factor. This regulation plays a prevalent role in timing hypocotyl elongation to late night, before light activation of phytochrome B (PHYB) and accumulation of DELLAs restricts PIF4 transcriptional activity.

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Integration of Light- and Brassinosteroid-Signaling Pathways by a GATA Transcription Factor in Arabidopsis

Cited by 239 publications

References 53 publications

Brassinosteroids regulate organ boundary formation in the shoot apical meristem of Arabidopsis

Brassinosteroids regulate organ boundary formation in the shoot apical meristem of Arabidopsis

Arabidopsis MICROTUBULE DESTABILIZING PROTEIN40 Is Involved in Brassinosteroid Regulation of Hypocotyl Elongation

BR-dependent phosphorylation modulates PIF4 transcriptional activity and shapes diurnal hypocotyl growth

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