UNIFOLIATA REGULATES LEAF AND FLOWER MORPHOGENESIS IN PEA

Background: The vegetative phenotype of the pea mutant unifoliata (uni ) is a simplification of the wild-type compound leaf to a single leafl et, Mutant uni plants are also self-sterile and the flowers resemble k nown floral meristem and organ identity mutants. In Antirrhinum and Ar abidopsis, mutations in the floral meristem identity gene FLORICAULAIL EAFY (FLO/LFY) affect flower development alone, whereas the tobacco FL O/LFY homologue, NFL, is expressed in vegetative tissues, suggesting t hat NFL specifies determinacy in the progenitor cells for both flowers and leaves. In this paper, we characterised the pea homologue of FLO/ LFY, Results: The pea cDNA homologue of FLO/LFY, PEAFLO, mapped to the uni locus in recombinant-inbred mapping populations and markers based on PEAFLO cosegregated with uni in segregating sibling populations. T he characterisation of two spontaneous uni mutant alleles, one contain ing a deletion and the other a point mutation in the PEAFLO coding seq uences, predicted that PEAFLO corresponds to UNI and that the mutant v egetative phenotype was conferred by the defective PEAFLO gene, Conclu sions: The uni mutant demonstrates that there are shared regulatory pr ocesses in the morphogenesis of leaves and flowers and that floral mer istem identity genes have an extended role in plant development, Pleio tropic regulatory genes such as UNI support the hypothesis that leaves and flowers derive from a common ancestral sporophyll-like structure, The regulation of indeterminacy during leaf and flower morphogenesis by UNI may reflect a primitive function for the gene in the pre-angios perm era.