Functional requirement of plant farnesyltransferase during development in arabidopsis

Arabidopsis era1 was identified as an abscisic acid-hypersensitive mutant c aused by disruptions or deletions of the gene for the beta subunit (AtFTB) of farnesyltransferase (FTase). The heterodimeric enzyme catalyzes the cova lent attachment of the 15-carbon farnesyl diphosphate to the C terminus of regulatory proteins and is essential for growth in yeast. The first disrupt ion of FTS in a multicellular context revealed several developmental and gr owth regulatory processes that require the function of FTase. The lack of F Tase activity in the Arabidopsis era1-2 FTB deletion mutant resulted in enl arged meristems and organs, supernumerary organs in floral whorls, arrested development of axillary meristems, late flowering, and homeotic transforma tions of flowers. Complementation of era1-2 with LeFTB, the tomato gene for the beta subunit of FTase, restored a normal phenotype and confirmed that the lesion is in AtFTB alone. The effect of this lesion on control of meris tem size and on developmental processes suggests the involvement of regulat ory proteins that require farnesylation for their function. At least three distinct processes that require the function of FTase were identified: regu lation of cellular differentiation in the meristems, meristem maintenance, and regulation of flower development. Together, these results provide a bas is for future studies on the involvement of FTase in specific developmental processes and for structure-function analysis of FTase in vivo.