DIRECTED TAGGING OF THE ARABIDOPSIS FATTY-ACID ELONGATION-1 (FAE1) GENE WITH THE MAIZE TRANSPOSON ACTIVATOR

The FATTY ACID ELONGATION1 (FAE1) gene of Arabidopsis is required for the synthesis of very long chain fatty acids in the seed, The product of the FAM gene is presumed to be a condensing enzyme that extends the chain length of fatty acids from C18 to C20 and C22, We report here t he cloning of FAE1 by directed transposon tagging with the maize eleme nt Activator (Ac). An unstable fae1 mutant was isolated in a line carr ying Ac linked to the FAE1 locus on chromosome 4, Cosegregation and re version analyses established that the new mutant was tagged by Ac. A D NA fragment flanking Ac was cloned by inverse polymerase chain reactio n and used to isolate FAE1 genomic clones and a cDNA clone from a libr ary made from immature siliques. The predicted amino acid sequence of the FAE1 protein shares homology with those of other condensing enzyme s (chalcone synthase, stilbene synthases, and beta-ketoacyl-acyl carri er protein synthase III), supporting the notion that FAE1 is the struc tural gene for a synthase or condensing enzyme, FAE1 is expressed in d eveloping seed, but not in leaves, as expected from the effect of the fae1 mutation on the fatty acid compositions of those tissues.