CaVIL1, a plant homeodomain gene that promotes flowering in pepper

CaVIL1 is a homolog of VIL1, a regulator of vernalization response in Arabidopsis and acts as a flowering promoter in pepper which does not respond to vernalization and photoperiod. As part of our goal to study the genetic and molecular basis of transition to flowering in pepper, we isolated the late-flowering mutant E-2698. Aside from late flowering, multiple pleiotropic alterations of the shoot structure, such as enlarged and distorted leaves, weak apical dominance, and reduced angle of the lateral branches were observed, indicating a broad role for the mutated gene in pepper development. Genetic mapping and sequence analyses revealed that the disrupted gene in E-2698 is the pepper homolog of VERNALIZATION INSENSITIVE 3-LIKE 1 (VIL1) that acts as a regulator of vernalization in Arabidopsis through chromatin modification. The pepper gene, CaVIL1, contains a plant homeodomain motif associated with chromatin modification and a VERNALIZATION INSENSITIVE 3-interacting domain that is truncated in E-2698 and in two other allelic mutants. Because pepper flowering does not respond to vernalization, we postulate that CaVIL1 regulates flowering time via chromatin modification of unknown targets. Expression analysis indicated that CaVIL1 activates the flowering promoter CaFLOWERING LOCUS T and represses the flowering repressor CaAPETALA2. Furthermore, CaVIL1 represses several genes from the FLOWERING LOCUS C (FLC)-LIKE clade that are clustered together in the pepper genome. This indicates their possible involvement in flowering regulation in this species. Our results show that CaVIL1 is a major regulator of flowering and interacts with other flowering promoters and repressors, as well as with FLC-LIKE genes whose function in flowering regulation is not yet known in pepper.