Basic helix-loop-helix gene family: Genome wide identification, phylogeny, and expression in Moso bamboo

Studies have shown that basic helix-loop-helix (bHLH) transcription factors play important roles in plant growth and survival, and response to various biotic/abiotic stresses. We identified a total of 448 bHLH genes. These genes were classified into 21 bHLH subfamilies, and most genes in a given subfamily had similar gene structures and conserved motifs. We identified 176 homologous pairs in the three species. We calculated Ka, Ks, and Ka/Ks to analyze the replication relationships among the three species. Multiple sequence analysis revealed that the PebHLH genes had the distinct bHLH structure. The gene ontology annotation analysis showed that the PebHLH genes had many molecular functions. Promoter cis-element analysis revealed that most of the PebHLH genes contained cis-elements that can respond to various biotic/abiotic stress-related events. The tissue expression patterns of the PebHLH genes indicated that most members were expressed in leaves, roots, and stems. Quantitative real-time PCR analysis showed that 21 selected PebHLH genes were differentially regulated after abscisic acid, drought, and methyl jasmonate treatments. This study has laid the basis for studying the functions of AtbHLH, OsbHLH, and PebHLH genes, and will contribute to future studies of the functions of bHLH genes in other plant species.