Genome-wide Analysis of the bHLH Transcription Factor Family and Functional Identification of bHLH Genes Related to Puerarin Biosynthesis in Pueraria lobata var. thomsonii (Benth.)

Abstract

Plant basic helix-loop-helix (bHLH) transcription factors are involved in diverse biological process. Several bHLH transcription factors have been functionally characterized in various crop species. However, no systematic and comprehensively identification of bHLH members has been in Pueraria lobata var. thomsonii (Benth.) (P. thomsonii), a traditional Chinese herb that is an excellent source of puerarin. Phylogenetic analysis showed that 219 bHLH genes were identified in the P. thomsonii and classified into 13 subfamilies. All the PlbHLH genes were distributed on the 11 chromosomes unevenly and the number of PlbHLH genes on each chromosome varied from 12 to 44. Both of tandem and segmental duplications were key factors driving bHLH gene family expansion in P. thomsonii. The gene structure analysis indicated that 20 conserved motifs were found in PlbHLH gene family, 185 PlbHLH members contain more than two introns, and genes within the same subfamily appeared to share similar intron-exon gene structures. The Ka/Ks analysis indicated PlbHLH gene family undergo purifying selection during evolution. The hierarchical clustering analysis indicated that 41 PlbHLHs showed root-specific expression patterns, and seven of them exhibited up-regulated expression pattern after MeJA treatment within 24 h. Using qRT-PCR validation, five puarian synthesis genes had a similar expression pattern with the seven PlbHLH genes in response to MeJA within 24 h. Together, our study provided a good foundation for further research into the regulatory mechanism of the seven candidate PlbHLH proteins for pueraria biosynthesis in P. thomsonii.

Genome-wide Identification of the BHLH Family in Chenopodium Quinoa

“…It has been found that bHLH proteins are involved in plant growth, development, and metabolism processes, but more importantly, in stress responses. To date, the bHLH genes in wheat, mulberry trees, Clerodendrum japonicum, and many other plant species [18][19][20] have been systematically identified and analyzed, but there is no report about the analysis of bHLH genes in Chenopodium quinoa.…”