Abstract
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 (GA3) content were different in the two rose cultivars. The overall change trend of the abscisic acid and GA3 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.
Highlights
Introduction iationsFlowering transition is one of the most important developmental processes of higher plants, which is controlled by endogenous and external environmental signals
Many studies have shown that the CONSTANS (CO) and FLOWERING LOCUS T(FT) genes are the core regulatory factors in the photoperiod pathway [3–5], and the CO-FT regulation mode is conservative in many species [6]
CO-like 2, SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1), AP2-like, FD, VERNALIZATION INSENSITIVE 3 (VIN3)-LIKE 1 (VIL1), and FRI 3 were the hub genes in modules related to continuous flowering
Summary
Flowering transition is one of the most important developmental processes of higher plants, which is controlled by endogenous and external environmental signals. As for the mechanism of plant flowering transition, the main regulatory pathways have been identified, including the photoperiod pathway, the vernalization pathway, the gibberellin pathway, the autonomous pathway, the aging-dependent pathway, and the temperature pathway [1,2]. Some other endogenous factors, such as glucose metabolism and integrators of flowering, can affect flowering transition [1,2]. Many studies have shown that the CONSTANS (CO) and FLOWERING LOCUS T(FT) genes are the core regulatory factors in the photoperiod pathway [3–5], and the CO-FT regulation mode is conservative in many species [6]. The CCT domain of the CO gene can bind to two CO responsive elements (COREs) at the proximal end of the FT promoter to promote its Licensee MDPI, Basel, Switzerland.
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