A CAPRICE gene of Rosa rugosa (RrCPC) suppresses the trichome formation of Arabidopsis

Rosa rugosa is a spice plant with important economic value in the world. Its stem is densely covered with thorns. Its anatomical structure, as a special form of epidermal hair with developed secondary structure, has always gained attention. However, the molecular mechanism of its developmental regulation remains to be studied. In this research, rose prickle types were first investigated and classified, and R. rugosa 'Zizhi' with only non-glandular prickles excavated. The number of prickles on the primary, secondary, and tertiary branches of R. rugosa 'Zizhi' were gradually decreased and corresponding tissues were used for transcriptome sequencing. 4588 differentially expressed genes were identified and GO enriched terms of 'highly intensified response to stimulus', 'cell periphery', and 'nucleic acid binding transcription factor activity', as well as KEGG enriched pathway of 'plant hormone signal transduction', were closely related to the development of rose prickles. CAPRICE (RrCPC) gene which upregulated with the decreasing prickle number was decided as a candidate gene involved in the prickle development of R. rugosa. RrCPC ectopic expression significantly inhibited trichomes in different organs of Arabidopsis by down-regulation of GL2 and other endogenous genes. It indicated that overexpression of RrCPC posed a significant competitive inhibition on the MBW complex. Meanwhile, consistent enrichment GO terms shared by rose and Arabidopsis suggested that regulation genes involved in prickle development may be overlapped with that of trichome. These results revealed that RrCPC was a negative regulator of the trichomes but its correlation with number of R. rugosa prickle was ambiguous. This study proved the wide difference in physiological structure of prickles and trichomes, and provided a potential gene for further genetic analysis of R. rugosa prickle formation.