Floral homeotic mutants in lily: double flower and Festiva phenotypes

Homeotic changes in floral organs of lily (Lilium spp.) are described in this chapter. Usually, lily flowers show similar organs in their first and second whorls called tepals. They constitute the appealing colourful features determining flower appearance. Stamens and the carpel appear as the third and fourth whorls, respectively. A double lily flower shows replacement of stamens by tepals and of its carpel by a new flower in a reiterated manner, similar to what is seen in the agamous mutant of Arabidopsis. A novel floral phenotype of lily, denominated festiva here, has never been reported in other species so far and shows a complete homeotic change of stamens into tepals, but keeps the carpel identity. We tried to explain these phenotypes taking into consideration all the evidence on the genetic mechanisms involved in flower development gathered over the last 15 years. This work launches challenges and encouragement for exploiting the molecular mechanisms involved in flower development of lily.