Identification And Characterization Of Soybean CCA1-like MYB Transcription Factor And Its Function Analysis Under Abiotic Stress

Soybean(Glycine max(Linn.)Merr.)is an important edible bean with high nutritional and economic value.It is widely cultivated around the world.However,drought,saline-alkali and other stresses greatly limit the production of soybean,so it is of great significance to explore stress-related regulatory factors and improve the adaptability of varieties through biotechnology.CCA1-like MYB transcription factor is a major subfamily of 1R MYB,which is characterized by a highly conserved SHAQK(Y/F)F sequence in a single MYB domain.In addition to participating in the regulation of the circadian clock,it also plays an important role in plant growth and development,flowering,senescence,hormone signal transmission,and biological and abiotic stress.In this study,we identified 6candidate genes from 54 CCA1-like MYB transcription factors in soybean,and screened a CCA1-like MYB transcription factor GmRVE8 a,which participates in the regulation of circadian clock and abiotic stress,and conducted further functional analysis.The main research results are as follows:1.Real-time quantitative PCR detection showed that the expression of GmRVE8 a,GmMYB127 and GmMYB128 among the 6 candidate MYB transcription factors showed rhythmic fluctuations with a period of about 24 h when the soybean was exposed to continuous light for 72 h.Under different abiotic stress treatments,the expression of 6 MYB transcription factors all changed significantly in different degrees.2.Phenotyping of GmRVE8 a transgenic Arabidopsis showed shorter petioles,later flowering and larger branch angles.The wild-type and GmRVE8 a overexpression lines were treated with salt stress and drought stress respectively.It was found that the germination rate and green seedling rate of the GmRVE8 a overexpression lines were not significantly different from that of the wild-type under salt and drought stress conditions,but the growth of the overexpression lines was better than that of the wild type;under soil salt stress and drought stress,the GmRVE8 a overexpression lines showed higher tolerance,that is,the overexpression of GmRVE8 a improves the tolerance of plants to salt stress and drought stress at the seedling stage.3.Through soybean hairy root transformation,the composite plants with overexpression and RNAi root were obtained.After salt stress treatment on the composite plants,it was found that the overexpression composite plants had the strongest tolerance to salt stress,followed by the wild type,and the RNAi composite plant had the worst tolerance.In other words,the overexpression of GmRVE8 a in roots could improve the tolerance of composite plants to salt stress.4.We constructed an overexpression vector of GmRVE8 a,and obtained GmRVE8 a transgenic soybean positive plants of T0 generation through Agrobacterium-mediated soybean genetic transformation technology,which provides a basis for further research.