Brassinosteroids(BRs)are a class of steroid hormones with great potential for use in crop improvement.De-repression is usually one of the key events in hormone signaling.However,how the stability of GSK2,the central n...Brassinosteroids(BRs)are a class of steroid hormones with great potential for use in crop improvement.De-repression is usually one of the key events in hormone signaling.However,how the stability of GSK2,the central negative regulator of BR signaling in rice(Oryza sativa),is regulated by BRs remains elusive.Here,we identify the U-box ubiquitin ligase TUD1 as a GSK2-interacting protein by yeast two-hybrid screening.We show that TUD1 is able to directly interact with GSK2 and ubiquitinate the protein.Phenotypes of the tud1 mutant are highly similar to those of plants with constitutively activated GSK2.Consistent with this finding,GSK2 protein accumulates in the tud1 mutant compared with the wild type.In addition,inhibition of BR synthesis promotes GSK2 accumulation and suppresses TUD1 stability.By contrast,BRs can induce GSK2 degradation but promote TUD1 accumulation.Furthermore,the GSK2 degradation process is largely impaired in tud1 in response to BR.In conclusion,our study demonstrates the role of TUD1 in BR-induced GSK2 degradation,thereby advancing our understanding of a critical step in the BR signaling pathway of rice.展开更多
Grain size is a key agronomic trait that determines the yield in plants.Regulation of grain size by brassinosteroids(BRs)in rice has been widely reported.However,the relationship between the BR signaling pathway and g...Grain size is a key agronomic trait that determines the yield in plants.Regulation of grain size by brassinosteroids(BRs)in rice has been widely reported.However,the relationship between the BR signaling pathway and grain size still requires further study.Here,we isolated a rice mutant,named small grain2(sg2),which displayed smaller grain and a semi-dwarf phenotype.The decreased grain size was caused by repressed cell expansion in spikelet hulls of the sg2 mutant.Using map-based cloning combined with a Mut Map approach,we cloned SG2,which encodes a plant-specific protein with a ribonuclease H-like domain.SG2 is a positive regulator downstream of GLYCOGEN SYNTHASE KINASE2(GSK2)in response to BR signaling,and its mutation causes insensitivity to exogenous BR treatment.Genetical and biochemical analysis showed that GSK2 interacts with and phosphorylates SG2.We further found that BRs enhance the accumulation of SG2 in the nucleus,and subcellular distribution of SG2 is regulated by GSK2 kinase activity.In addition,Oryza sativa OVATE family protein 19(OsOFP19),a negative regulator of grain shape,interacts with SG2 and plays an antagonistic role with SG2 in controlling gene expression and grain size.Our results indicated that SG2 is a new component of GSK2-related BR signaling response and regulates grain size by interacting with Os OFP19.展开更多
基金supported by the Hainan Yazhou Bay Seed Laboratory(B21HJ0215)the National Natural Science Foundation of China(nos.U21A20208,31900177,31901534,31871587)+1 种基金the Central Publicinterest Scientific Institution Basal Research Fund(no.S2022ZD02)D.L.was funded by the China Postdoctoral Science Foundation(2020M670548).
文摘Brassinosteroids(BRs)are a class of steroid hormones with great potential for use in crop improvement.De-repression is usually one of the key events in hormone signaling.However,how the stability of GSK2,the central negative regulator of BR signaling in rice(Oryza sativa),is regulated by BRs remains elusive.Here,we identify the U-box ubiquitin ligase TUD1 as a GSK2-interacting protein by yeast two-hybrid screening.We show that TUD1 is able to directly interact with GSK2 and ubiquitinate the protein.Phenotypes of the tud1 mutant are highly similar to those of plants with constitutively activated GSK2.Consistent with this finding,GSK2 protein accumulates in the tud1 mutant compared with the wild type.In addition,inhibition of BR synthesis promotes GSK2 accumulation and suppresses TUD1 stability.By contrast,BRs can induce GSK2 degradation but promote TUD1 accumulation.Furthermore,the GSK2 degradation process is largely impaired in tud1 in response to BR.In conclusion,our study demonstrates the role of TUD1 in BR-induced GSK2 degradation,thereby advancing our understanding of a critical step in the BR signaling pathway of rice.
基金supported by the Key Laboratory of Biology,Genetics and Breeding of Japonica Rice in Mid-lower Yangtze River,Ministry of Agriculture of China,Jiangsu Collaborative Innovation Center for Modern Crop Production,Jiangsu Plant Gene Engineering Research Center and the grants from the National Natural Science Foundation of China(32172024)Jiangsu Agricultural Science and Technology Innovation Fund(CX19(1002))Natural Science Foundation of Jiangsu Province,Major Project(BK20212010)。
文摘Grain size is a key agronomic trait that determines the yield in plants.Regulation of grain size by brassinosteroids(BRs)in rice has been widely reported.However,the relationship between the BR signaling pathway and grain size still requires further study.Here,we isolated a rice mutant,named small grain2(sg2),which displayed smaller grain and a semi-dwarf phenotype.The decreased grain size was caused by repressed cell expansion in spikelet hulls of the sg2 mutant.Using map-based cloning combined with a Mut Map approach,we cloned SG2,which encodes a plant-specific protein with a ribonuclease H-like domain.SG2 is a positive regulator downstream of GLYCOGEN SYNTHASE KINASE2(GSK2)in response to BR signaling,and its mutation causes insensitivity to exogenous BR treatment.Genetical and biochemical analysis showed that GSK2 interacts with and phosphorylates SG2.We further found that BRs enhance the accumulation of SG2 in the nucleus,and subcellular distribution of SG2 is regulated by GSK2 kinase activity.In addition,Oryza sativa OVATE family protein 19(OsOFP19),a negative regulator of grain shape,interacts with SG2 and plays an antagonistic role with SG2 in controlling gene expression and grain size.Our results indicated that SG2 is a new component of GSK2-related BR signaling response and regulates grain size by interacting with Os OFP19.
