Study On The Transcription Factor OsMADS57 Regulating Gibberellin Catabolism And Plant Height In Rice

Rice?Oryza sativa?,one of the dominant grain crops in the world,is also an important monocotyledon model plant.Plant height is an important agronomic trait that determines grain yield.Although many semi-dwarf and dwarf-related genes involved in plant height development have been identified,the precise mechanism underlying plant height development remains unclear.In plants,MADS-box family proteins are important transcription factors,which not only control the development of floral organs but regulate the development of roots,stems and leaves as well as the stress response.OsMADS57,mainly expressed in leaves,is reported to regulate bud growth and cold adaption in rice.However,the function of OsMADS57 in plant height development remains unknown.Therefore,exploring the function of OsMADS57 in plant height development and its regulation mechanism is of great significance for enriching the function of the MADS-box gene family.In this study,rice T-DNA insertion mutants were used as the experimental materials to study the biological function of OsMADS57in regulating rice plant height development.The main work is as follows:?1?osmads57 mutant plants showed the semi-dwarf phenotype and retarded elongation of the uppermost internode.The mutant plants showed a semi-dwarf phenotype at seedling stage as well as at maturity,and the length of the uppermost internode at maturity was significantly reduced,which resulted in a severe panicle enclosure phenotype in mutant plants.Accordingly,the cell length was also greatly reduced in the uppermost internode in mutant plants.In addition,the mutants also showed delayed flowering,reduced seed setting rate and seed germination rate.?2?osmads57 mutant plants had increased sensitivity to gibberellic acid?GA₃?.Under GA₃ treatment,the mutant plants were more sensitive to GA₃ than wild type.Moreover,the transcription of OsMADS57 was induced by paclobutrazol?PAC?but inhibited by GA₃.?3?osmads57 mutant plants accumulated lower levels of GA₃ than wild type.Compared to that in wild type,the GA₃ content was significant reduced in mutant plants.In addition,OsMADS57 affected the transcription of genes involved in gibberellin?GA?metabolism,and the transcription of the GA biosynthetic genes in mutant plants were down-regulated.?4?OsMADS57 protein directly bound to the promoter sequences of OsGA2ox3and EUI1 to regulate the transcription of OsGA2ox3 and EUI1,encoding GA deactivating enzymes.Through luciferases?LUC?activity assay,we found that the LUC activity was significantly reduced when OsGA2ox3_Pro:LUC or EUI1_Pro:LUC was coexpressed with 35S:OsMADS57 in rice protoplasts,indicating that OsMADS57protein inhibits the transcription of OsGA2ox3 and EUI1.Electrophoretic mobility shift assay?EMSA?also showed that OsMADS57 protein directly bound to the promoter sequences of OsGA2ox3 and EUI1 to regulate their expression.?5?OsMADS57 affected the transcription of genes involved in plant height development.RNA sequencing?RNA-seq?and quantitative polymerase chain reaction?Q-PCR?analysis showed that the transcription of multiple expansin genes was down-regulated in mutant plants,and the transcript levels of genes involved in plant height development were also changed greatly.Together,these results indicated that OsMADS57 regulates the expression of genes involved in GA catabolism,thereby affecting GA content and plant height development in rice.Our study not only reveals the molecular mechanism by which OsMADS57regulates the plant height development,but provides a theoretical guidance for the cultivation of desirable plant architecture.