Identification and Expression Analysis of bHLH Transcription Factor Family Genes in Purple Potato

The bHLH transcription factor family was known as the second largest transcription factor family, which plays important roles in the process of plant growth and development, the regulation of anthocyanin biosynthesis pathway, adversity stress and etc. In order to discover the bHLH genes related to the synthesis of anthocyanins, bHLH genes were screened based on the transcriptome sequencing data of purple potato, and the sequence of bHLH were analyzed by bioinformatics method, and the expression and function of bHLH genes were analyzed and predicted at different stages. Then the expression levels of five bHLH genes related to anthocyanin synthesis at different developmental stages were analyzed by RT-qPCR. The results showed that 103 bHLH genes in purple potatoes were screened, and the sizes of encoded proteins size was ranged from 129 aa to 699 aa, and the isoelectric point was ranged from 4.65 to 9.75, belonging to hydrophilic proteins. There was a highly conserved H5-E9-R12 sequence（His5-Glu9-Arg12） in the basic region, which was composed of 15 basic amino acids. There were highly conserved leucine（L）, arginine（R）and valine（V）in two helical regions. Two conservative motifs were predicted, and the longest motif contained 35 amino acids. In different developmental stages, 36 bHLH genes were down-regulated expression, and 67 bHLH genes were up-regulated expression trend, of which 41 bHLH genes were differentially expressed during the three developmental stages; 103 bHLH genes of purple potato were divided into 13 sub-families clustering with bHLH family Arabidopsis thaliana; GO enrichment analysis revealed that 103 bHLH genes were widely involved in 72 functions such as anthocyanin biosynthesis, defense response, growth and development, among which five bHLH genes might be involved in the synthesis of anthocyanins and flavonoids. The results of RT-qPCR were consistent with sequencing expression trends.