Overexpression of the cucumber LEAFY homolog CFL and hormone treatments alter flower development in gloxinia (Sinningia speciosa)

Leafy (LFY) and LFY-like genes control the initiation of floral meristems and regulate MADS-box genes in higher plants. The Cucumber-FLO-LFY (CFL) gene, a LFY homolog in Cucumis sativus L. is expressed in the primordia, floral primordia, and each whirl of floral organs during the early stage of flower development. In this study, functions of CFL in flower development were investigated by overexpressing the CFL gene in gloxinia (Sinningia speciosa). Our results show that constitutive CFL overexpression significantly promote early flowering without gibberellin (GA3) supplement, suggesting that CFL can serve functionally as a LFY homolog in gloxinia. Moreover, GA3 and abscisic acid (ABA) treatments could modulate the expression of MADS-box genes in opposite directions. GA3 resembles the overexpression of CFL in the expression of MADS-box genes and the regeneration of floral buds, but ABA inhibits the expression of MADS-box genes and flower development. These results suggest that CFL and downstream MADS-box genes involved in flower development are regulated by GA3 and ABA.