Silencing ofEcFLO, AFLORICAULA/LEAFYGene of the California Poppy (Eschscholzia californica), Affects Flower Specification in a Perigynous Flower Context

Flowers are reproductive shoots produced by determinate floral meristems. The role ofFLORICAULA/LEAFY-like genes in the specification of flowers varies between lineages and has not been characterized in a basal eudicot species. Here we report the phenotypic effects of virus-induced silencing ofEcFLO, aFLORICAULA/LEAFYhomologue in the California poppyEschscholzia californica.EcFLOsilencing resulted in repeated sepal and petal whorl formation and internodes between calyxes. A subset of silenced flowers showed reduced petal and stamen numbers and mosaic identities of floral organs. We also provide expression data of other floral regulator genes and conclude thatEcFLOcontributes to certain aspects of flower development, reflecting both functional conservation and differentiation among basal eudicots, core eudicots, and monocot grasses.EcFLOis involved in stamen and petal initiation, floral organ identity delimitation, suppression of internodes, and limitation of the number of perianth whorls. Further, silencing ofEcFLOallows insights into perigynous flower development inEschscholzia. We demonstrate that receptacle cup formation, by which the perianth and the androecium are elevated above the gynoecium late in flower development, responds to the initiation of the synsepalous calyx.