FALSIFLORA, the tomato orthologue of FLORICAULA and LEAFY, controls flowering time and floral meristem identity

Abstract

Characterization of the tomato falsiflora mutant shows that fa mutation mainly alters the development of the inflorescence resulting in the replacement of flowers by secondary shoots, but also produces a late-flowering phenotype with an increased number of leaves below first and successive inflorescences. This pattern suggests that the FALSIFLORA (FA) locus regulates both floral meristem identity and flowering time in tomato in a similar way to the floral identity genes FLORICAULA (FLO) of Antirrhinum and LEAFY (LFY) of Arabidopsis. To analyse whether the fa phenotype is the result of a mutation in the tomato FLO/LFY gene, we have cloned and analysed the tomato FLO/LFY homologue (TOFL) in both wild-type and fa plants following a candidate gene strategy. The wild-type gene is predicted to encode a protein sharing 90% identity with NFL1 and ALF, the FLO/LFY-like proteins in Nicotiana and Petunia, and about 80 and 70% identity with either FLO or LFY. In the fa mutant, however, the gene showed a 16 bp deletion that results in a frameshift mutation and in a truncated protein. The co-segregation of this deletion with the fa phenotype in a total of 240 F2 plants analysed supports the idea that FA is the tomato orthologue to FLO and LFY. The gene is expressed in both vegetative and floral meristems, in leaf primordia and leaves, and in the four floral organs. The function of this gene in comparison with other FLO/LFY orthologues is analysed in tomato, a plant with a sympodial growth habit and a cymose inflorescence development.