THE GENETICS OF STAMENOID PETAL PRODUCTION IN OILSEED RAPE (BRASSICA-NAPUS) AND EQUIVALENT VARIATION IN ARABIDOPSIS-THALIANA

The agronomic potential of a Brassica napus variant with petalless flo wers was compromised by an associated detrimental change in leaf morph ology. Genetic analysis demonstrated the cosegregation of genes contro lling both morphologies. Two STAP loci controlling the production of f lowers with stamenoid petals were mapped to homoeologous locations in the genome of B. napus. The STAP loci were probably duplicate genes be cause they exhibited an epistatic interaction such that only plants ho mozygous for recessive scap alleles at both loci expressed the Variant phenotype. The CURLY LEAF (CLF) gene of Arabidopsis thaliana pleiotro pically influences both flower and leaf morphologies. The cloned CLF g ene of Arabidopsis was homologous to a polymorphic B. napus locus coin cident with one of the B. napus STAP loci. The possibility that CLF is a candidate gene for STAP suggests that the variant stap alleles of B . napus exert pleiotropic effects over both flower and leaf morphologi es.