title: OsGSR1 is involved in crosstalk between gibberellins and brassinosteroids in rice.
abstract: Gibberellins (GAs) and brassinosteroids (BRs), two growth-promoting phytohormones, regulate many common physiological processes. Their interactions at the molecular level remain unclear. Here, we demonstrate that OsGSR1, a member of the GAST (GA-stimulated transcript) gene family, is induced by GA and repressed by BR. RNA interference (RNAi) transgenic rice plants with reduced OsGSR1 expression show phenotypes similar to plants deficient in BR, including short primary roots, erect leaves and reduced fertility. The OsGSR1 RNAi transgenic rice shows a reduced level of endogenous BR, and the dwarf phenotype could be rescued by the application of brassinolide. The yeast two-hybrid assay revealed that OsGSR1 interacts with DIM/DWF1, an enzyme that catalyzes the conversion from 24-methylenecholesterol to campesterol in BR biosynthesis. These results suggest that OsGSR1 activates BR synthesis by directly regulating a BR biosynthetic enzyme at the post-translational level. Furthermore, OsGSR1 RNAi plants show a reduced sensitivity to GA treatment, an increased expression of the GA biosynthetic gene OsGA20ox2, which is feedback inhibited by GA signaling, and an elevated level of endogenous GA: together, these suggest that OsGSR1 is a positive regulator of GA signaling. These results demonstrate that OsGSR1 plays important roles in both BR and GA pathways, and also mediates an interaction between the two signaling pathways.
authors.affiliation: Research Center for Molecular & Developmental Biology, Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.forename: Zhen
authors.initials: Z
authors.lastname: Wang
authors.forename: Yunyuan
authors.initials: Y
authors.lastname: Xu
authors.forename: Se-Hwan
authors.initials: SH
authors.lastname: Joo
authors.forename: Seong-Ki
authors.initials: SK
authors.lastname: Kim
authors.forename: Zhen
authors.initials: Z
authors.lastname: Xue
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Xu
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Wang
authors.forename: Kang
authors.initials: K
authors.lastname: Chong
mesh_terms: D060406:Brassinosteroids; D002777:Cholestanols / Q000378:metabolism*; D002784:Cholesterol / Q000031:analogs & derivatives / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D005875:Gibberellins / Q000378:metabolism* / Q000494:pharmacology; D012275:Oryza / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D010641:Phenotype; D010840:Phytosterols / Q000378:metabolism; D010937:Plant Growth Regulators / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D018749:RNA, Plant / Q000235:genetics; D013260:Steroids, Heterocyclic / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
chemical_list: D060406:Brassinosteroids; D002777:Cholestanols; D005875:Gibberellins; D010840:Phytosterols; D010937:Plant Growth Regulators; D010940:Plant Proteins; D018749:RNA, Plant; D013260:Steroids, Heterocyclic; C021273:campesterol; D002784:Cholesterol; C002537:24-methylenecholesterol; C023623:brassinolide