Molecular Characterization of bHLH Transcription Factor Family in Rose (Rosa chinensis Jacq.) under Botrytis cinerea Infection

Abstract

Rose (Rosa chinensis Jacq.) is an important economic ornamental crop and its yield is affected by different biotic and abiotic stresses. Among the biotic stresses, the gray mold disease caused by Botrytis cinerea is a serious threat to rose production. The basic helix-loop-helix (bHLH) is a large transcription factor family involved in several vital plant physiological processes, including growth, development, and stress response. However, no substantial reports exist on bHLH genes in rose. Here, the genome-wide identification, characterization, and expression analysis of the rose bHLH (RcbHLH) genes was carried out. In total, 100 RcbHLHs were identified in the rose genome and mapped onto different rose chromosomes. The gene duplication analysis revealed both tandem and segmental duplications in RcbHLHs. The RcbHLHs among other plant bHLHs were divided into 21 sub-groups on the phylogenetic tree. Additionally, prediction of the different cis-regulatory elements and the gene ontology of the identified RcbHLHs indicated their possible functions in rose plants. The expression analysis of selected RcbHLHs genes in two contrasting rose varieties (A29 = Black Baccara and XS = Sweet Avalanche) under B. cinerea infection provided insights into the involvement of RcbHLHs in rose–B. cinerea interactions. Moreover, this study provided details on the bHLH family genes in rose and their potential roles in rose defense against B. cinerea infection.