Cloning and functional analysis of GhMYB6 gene related to cotton Verticillium wilt resistance

【Objective】To clone GhMYB6 gene of MYB family in upland cotton and analyze its function in response to cotton Verticillium wilt,so as to provide reference for exploring cotton genes related to disease-resistance and disease-resistant cotton breeding.【Method】Based on data of cotton transcriptome,the gene GhMYB6 in response to Verticillium wilt infection was screened and cloned,and its sequences was analyzed by bioinformatics. Its expression patterns induced by Verticillium wilt were detected by real-time fluorescence quantitative PCR(qRT-PCR). Biological function of cotton resistance to Verticillium wilt was preliminarily verified by virus-induced gene silencing(VIGS) technology.【Result】GhMYB6 open reading frame(ORF) was 258 bp,encoding 85 amino acid residues,with a theoretical point(pI) of 9.34,fat coefficient of 73.41,average hydrophobicity of-0.793,relative molecular mass of 9.86 kD,instability index of 73.41,indicating that it encoded non-transmembrane,alkaline,hydrophilic protein located in the nucleus,with a SANT domain in the 11^th -63^rd amino acids. Protein GhMYB6 and Gossypium raimondii GrMYB6 were clustered in the same small branch,indicating a close relationship between the two. After V991 infection,relative expression of GhMYB6 was extremely significantly down-regulated compared that of control(uninfected treatment,CK) (P<0.01) at 6 and 12 h,significantly up-regulated(P<0.05,the same below) at 72 h and no significant difference between it and CK was found at 24 and 48 h(P>0.05).After inhibiting GhMYB6 gene expression by VIGS technology,compared with the negative control plant TRV:00,wilting and leaf yellowing of GhMYB6 gene silenced plants was more serious,the disease index was significantly higher,stem brow-ning was more serious,and the number of fungal hyphae in stem segments was higher.【Conclusion】GhMYB6 gene responds to Verticillium dahliae V991 infection. After inhibiting GhMYB6 gene expression,cotton is more sensitive to Verticillium wilt and the resistance is significantly reduced,so it is speculated that GhMYB6 is a positive regulator of cotton Verticillium wilt resistance.