Biological Function And Molecular Mechanism Of GmMYB133 In Soybean

CCA1-like MYB transcription factors are the main subfamily of 1R MYB,which harbored SHAQK(Y/F)F sequence in a single MYB domain.Besides the regulation of circadian clock,it also works in plant growth and development,flowering,senescence,hormone signaling and biotic and abiotic stress.GmMYB133 is a CCA1-like MYB transcription factor identified from soybean and participated in the biosynthesis of isoflavone,and its transgenic Arabidopsis showed dwarf and compact plant characteristics.Based on the research background and the previous work in the laboratory,this paper aims to explore function and mechanism of GmMYB133 by phenotype observation,transcriptome sequencing analysis of Arabidopsis and other experiments,the main results are as follows:1.Many light-responsive elements related to circadian clock,hormone-responsive and stress-responsive elements were found in the promoter of GmMYB133.GUS staining of GmMYB133pro::GUS transgenic Arabidopsis indicated that GmMYB133expressed in all tissues except seeds,and the expression level is higher in vascular tissues.The expression of GmMYB133 in light treated soybean showed rhythm fluctuation with~24 hours.2.GmMYB133 transgenic Arabidopsis showed shorter hypocotyls,longer hypocotyls in dark and late flowering.Seed germination rate is higher than WT under salt stress and salt and drought resistance of seedlings are stronger.3.By transcriptome sequencing analysis and real-time quantitative PCR,it was found that overexpression of GmMYB133 in Arabidopsis caused changes in expression of circadian clock and hormone-related genes.Circadian regulators CCA1,LHY and PRR5 were up-regulated,and different fluctuation rhythm occurred in transgenic and WT Arabidopsis,and PRR5 changed significantly in particular.Hormone-related IAA synthesis-related genes expression decreased,degradation-related genes expression increased,and IAA content in GmMYB133 transgenic Arabidopsis was lower.BR synthetic gene DWF4 was down-regulated,and LBO1,a key gene in the synthesis of strigolactones,was up-regulated significantly.Three hormone-related genes with large fold changes in transcriptome sequencing were selected for Y1H experiment.The results showed that selected genes were not the target genes of GmMYB133,and its mechanism needs to be further explored.4.The Y2H cDNA library was established with soybean 50d and 60d embryo,the titer concentration of the library was 5.8×10~7cfu/ml.Nine proteins may interacted with GmMYB133 were screened from yeast cDNA library and mating efficiency was 2.68%.According to NCBI and Phytozome database,the target proteins were Leucine-rich F-box protein,senescence-associated protein,ADP-ribosyltransferase,Regulator of rDNA transcription protein and FBD-associated F-box protein,these studies laid the foundation for further understanding of functional mechanism of GmMYB133.