CAPRICE family genes control flowering time through both promoting and repressing CONSTANS and FLOWERING LOCUS T expression

CAPRICE (CPC) and six additional CPC family genes encode R3-type MYB transcription factors involved in epidermal cell fate determination, including Arabidopsis root hair and trichome differentiation. Previously, we reported that the CPC and CPC family genes TRIPTYCHON (TRY) and CAPRICE LIKE MYB3 (CPL3) also affect flowering time. The cpl3 mutant plants flower earlier, with fewer but larger leaves, than do wild type plants, and mutations in CPC or TRY delay flowering in the cpl3 mutant. In this study, we examined flowering time, leaf number, and fresh weight for CPC family gene double and triple mutants. Mutation in ENHANCER OF TRY AND CPC1 (ETC1) shortened the flowering time of the cpl3 single mutant. Mutation in ETC2 significantly reduced fresh weight in the cpl3 mutant. Expression levels of the flowering-related genes CONSTANS (CO) and FLOWERING LOCUS T (FT) were higher in the cpl3 mutant than in wild type plants. The high expression levels of CO and FT in cpl3 were significantly reduced by mutations in CPC, TRY, ETC1, or ETC2. Our results suggest that CPC family genes antagonistically regulate flowering time through CO and FT expression.