The Basic/Helix-Loop-Helix Transcription Factor Family Gene RcbHLH112 Is a Susceptibility Gene in Gray Mould Resistance of Rose (Rosa Chinensis).

The basic/helix-loop-helix () family is a major family of transcription factors in plants. Although it has been reported that plays a defensive role against pathogen infection in plants, there is no comprehensive study on the -related defence response in rose ( sp.). In this study, a genome-wide analysis of family genes () in rose was carried out, including their phylogenetic relationships, gene structure, chromosome localization and collinearity analysis. Via phylogenetic analysis, a total of 121 genes in the rose genome were divided into 21 sub-groups. These are unevenly distributed in all 7 chromosomes of rose. The occurrence of gene duplication events indicates that whole-genome duplication and segmental duplication may play a key role in gene duplication. Ratios of non-synonymous to synonymous mutation frequency (Ka/Ks) analysis showed that the replicated genes mainly underwent purification selection, and their functional differentiation was limited. Gene expression analysis showed that 46 were differentially expressed in rose petals upon infection. It is speculated that these are candidate genes that regulate the response of rose plants to infection. Virus-induced gene silencing (VIGS) confirmed that in rose is a susceptibility factor for infection with . This study provides useful information for further study of the functions of the rose gene family.