Differentially Expressed Genes Related to Flowering Transition between Once- and Continuous-Flowering Roses.

Roses are the most important cut flower crops and widely used woody ornamental plants in gardens throughout the world, and they are model plants for studying the continuous-flowering trait of woody plants. To analyze the molecular regulation mechanism of continuous flowering, comparative transcriptome data of once- and continuous-flowering roses in our previous study were used to conduct weighted gene co-expression network analysis (WGCNA) to obtain the candidate genes related to flowering transitions. The expression patterns of candidate genes at different developmental stages between Rosa chinensis "Old Blush" (continuous-flowering cultivar) and R. "Huan Die" (once-flowering cultivar) were investigated, and the relationship of the key gene with the endogenous hormone was analyzed. The results showed that the expression trends of VIN3-LIKE 1 ( VIL1 ), FRIGIDA- LIKE 3 ( FRI3 ), APETALA 2- LIKE ( AP2-like ) and CONSTANS-LIKE 2 ( CO-like 2 ) genes were significantly different between "Old Blush" and "Huan Die", and the expression trends of SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 ( SOC1 ) and CO-like 2 were consistent in the flowering transition of "Old Blush" under different environments. The changes in cytokinin and gibberellic acid (GA 3 ) content were different in the two rose cultivars. The overall change trend of the abscisic acid and GA 3 in the flowering transition of "Old Blush" under different environments was consistent. The promoter sequence of CO-like 2 contained a P-box element associated with gibberellin response, as well as binding sites for transcription factors. In a word, we found CO-like 2 associated with continuous flowering and some factors that may synergistically regulate continuous flowering. The results provided a reference for elucidating the molecular regulatory mechanisms of continuous-flowering traits in roses.