Functional Characterization of Members of a Clade of F-box Proteins in Arabidopsis thaliana

In Arabidopsis, the F-box gene family encodes a large number of proteins postulated to act as substrate selectors for proteasome-mediated protein degradation. Recent reports document the importance of F-box proteins in developmental and metabolic signaling. Our microarray analyses of inflorescences of the brevipedicellus(bp) mutant indicate several F-box proteins are upregulated, suggesting that BP represses these genes in wild type plants to condition normal inflorescence development. We undertook analyses to examine the function of these proteins and their contribution to the pleiotropic phenotypes of bp. Yeast-2-hybrid screens revealed that the F-box protein At1g80440 binds to phenylalanine ammonia lyase-1(PAL1), the gateway enzyme of phenylpropanoid metabolism. Transgenic lines driven by the 35S cauliflower mosaic virus were attained but could not be propagated, suggesting a fatal phenotype. BP driven F-box expression results in phyllotaxy defects, manifest as alterations in the emergence of inflorescence and floral meristems in the axils of some cauline leaves.MAS