Characterization of the REVEILLE family in Rosaceae and role of PbLHY in flowering time regulation

Abstract

Background: The circadian clock integrates endogenous and exogenous signals and regulates various physiological processes in plants. REVEILLE (RVE) proteins play critical roles in circadian clock system, especially CCA1 (CIRCADIAN CLOCK ASSOCIATED 1) and LHY (LATE ELONGATED HYPOCOTYL), which also participate in flowering regulation. However, little is known about the evolution and function of the RVE family in Rosaceae species, especially in Pyrus bretschneideri. Results: In this study, we performed a genome-wide analysis and identified 51 RVE genes in seven Rosaceae species. The RVE family members were classified into two groups based on phylogenetic analysis. Dispersed duplication events and purifying selection were the main drivers of evolution in the RVE family. Moreover, the expression patterns of ten PbRVE genes were diverse in P. bretschneideri tissues. All PbRVE genes showed diurnal rhythms under light/dark cycles in P. bretschneideri leaves. Four PbRVE genes also displayed robust rhythms under constant light conditions. PbLHY, the gene with the highest homology to AtCCA1 and AtLHY in P. bretschneideri, is localized in the nucleus. Ectopic overexpression of PbLHY in Arabidopsis delayed flowering time and repressed the expression of flowering time-related genes. Conclusion: These results contribute to improving the understanding and functional research of RVE genes in P. bretschneideri.