Lilium longiflorum and molecular floral development: the ABCDE model

Because lily (Lilium longiflorum Thunb.) is an important cut-flower crop, molecular characterisation of genes that are involved in flower morphology could help breeders to develop novel floral architectures in this species. The early ABC model for flower development emerged more than 10 years ago from studies with Arabidopsis thaliana, Antirrhinum majus and petunia. Since then, floral identity genes have been studied in many other species as well and the studies evolved to the so-called ABCDE model. However, the lily ABCDE genes have only been studied in the last four years. Here, we review the current status of the molecular model of flower development in model species and lily, and present two homeotic floral mutants that we have found in Lilium spp., one of which is a newly identified phenotype, festiva, never reported earlier, not even in the model species Arabidopsis. This phenotype shows homeotic conversion of stamens into petals while keeping the carpel identity unchanged. Further characterisation of more homeotic floral genes in lily and studies of the genetic configuration of lily mutants such as festiva may help to develop new tools for molecular breeding of this species.