紫草LeMYC基因的克隆及表达分析

LeMYC is a novel member of the basic helix-loop-helix (bHLH) family that was cloned from Lithospermum erythrorhizon by using rapid amplification of cDNA ends method. Bioinformatics analyses showed that the predicted LeMYC protein contained a potential bHLH domain and was highly homologous to AtMYC2 from Arabidopsis thaliana. The promoter of LeMYC was further cloned to analyze its expression pattern, and sequence analysis revealed a number of potential regulatory motifs related to tissue-specific gene expression and abiotic and biotic stress responses. Real-time PCR results suggested that LeMYC was significantly induced transiently during the early stage when L. erythrorhizon cells were transferred from a B5 to an M9 medium to form shikonin. Exogenous methyl jasmonate (MeJA), an effective inducer of shikonin accumulation, also remarkably induced the rapid LeMYC expression. By contrast, ibuprofen (IBU), an inhibitor of jasmonate biosynthesis, significantly inhibited LeMYC expression. Tissue-specific expression analysis showed that LeMYC mRNA predominantly accumulated in the roots where shikonin was biosynthesized. These results indicated that LeMYC gene could be a novel member of the bHLH gene family and may have an important function in shikonin formation.