Photoperiod pathway regulates expression of MAF5 and FLC that encode MADS-box transcription factors of the FLC family in Arabidopsis

Abstract

The control of flowering by day length was the first photoperiodic response to be described and is also one of the most characterized in many plants. The circadian clock plays a pivotal role in the photoperiodic flowering pathway. In Arabidopsis, flowering time is controlled by the photoperiod as well as by the gibberellic acid and vernalization/autonomous pathways. FLOWERING LOCUS C (FLC), a MADS box protein, has been shown to be a key floral repressor in the vernalization/autonomous pathways. Although the roles and regulation of floral activators GIGANTEA, CONSTANS, and FLOWERING LOCUS T in the photoperiodic flowering pathway have been well characterized, those of the floral repressors are not well understood. Here, we demonstrate that the MADS AFFECTING FLOWERING 5 (MAF5) gene, one of the FLC family members, shows a diurnal expression pattern in light/dark cycles and that both gain- and loss-of-function mutations in the photoperiod pathway affect the gene expression of MAF5 and FLC. These results highlight the possible roles of MAF5 and FLC in crosstalk between the photoperiod and vernalization/autonomous pathways in Arabidopsis.