Cloning And Expression Analysis Of SmMYB1 Gene In Saussurea Medusa Maxim

Saussurea medusa Maxim,from the family Compositae,is a kind of typical alpine plant growing in the Qinghai-Tibet plateau,which is highly adaptive capabilities to extreme environments.Strong UV radiation is one of the main environmental factors in the Qinghai-Tibet plateau.It has important theoretical significance for revealing the adaptive mechanisms of alpine plants to the environments through studying molecular adaptation strategies of S.medusa to the UV radiation.In this study,S.medusa was used as an experimental material.MYB gene related to anthocyanin synthesis was cloned by RT-PCR with RACE technology,and the function of this gene and its expression pattern under UV radiation were studied.Main results were concluded as follows:1.The length of SmMYB1 cDNA(Gen Bank: MT188153.1)was 1 011 bp encoding 269 amino acids,the sequence of gDNA(Gen Bank: MT188154.1)contained two introns and three extrons.Bioinformatics analysis showed that SmMYB1 protein had more high similarity with MYB in asteraceae contained the[DE]Lx(2)[RK]x(3)Lx(6)Lx(3)R and ANDV motifs,and belonged to the sixth subfamily of Arabidopsis thaliana.The length of SmMYB1 promter(Gen Bank:MT188154.1)was 1407 bp,which contained many light responsive elements.2.qRT-PCR showed that SmMYB1 gene was expressed in roots,stems,leaves and flowers,and the highest expression emerged in the flowers.Under UV radiation stress,the expression of SmMYB1 reached the highest at 4 h,and then decreased gradually.It was speculated that SmMYB1 could regulate anthocyanin synthesis and was involved in the UV responsive pathway.3.The promoter(Gen Bank:MT634229)of SmDFR,a downstream gene of SmMYB1 was cloned.There was the conserved MYB binding elements in the DFR promoter regions of both S.medusa and other Compositae plants,and a MYB binding element(MYBPLANT)in the upstream of SmDFR promoter was also identified.Yeast one-hybrid experiments revealed the binding possibility of SmMYB1 protein and SmDFR promoter.These results suggested that SmMYB1 regulated anthocyanin synthesis by up-regulating SmDFR expression.4.SmHY5(Gen Bank: MW590585),a upstream gene of SmMYB1 was cloned.SmHY5 and HY5 of other Compositae plants and A.thaliana are highly conserved,especially in the b-ZIP domain and the COP1 protein interaction domain.This study provides a foundation for the further study of SmHY5 regulating SmMYB1 in order to reveal how light signal regulated anthocyanin synthesis in S.medusa.