The isolation and sequence analysis of two seed-expressed acyl carrier protein genes from Brassica napus

Abstract

Genomic Southern blot analysis of Brassica napus DNA indicates that seed-expressed acyl carrier protein (ACP) is encoded by a multigene family of some 35 genes/haploid genome. Two genomic clones encoding B. napus ACP have been isolated and sequenced. The coding sequences of the 2 respective genes were found to be perfectly homologous to 2 distinct B. napus seed-expressed cDNAs and therefore represent seed-expressed forms of ACP. The 2 genomic ACP sequences share 94% homology within their coding sequences. Both genes are interrupted by 3 intervening sequences whose position within the 2 coding sequences is conserved. RNase protection studies were used to map the transcription start site of one of the genes and to provide further evidence that the gene is seed-expressed. The expression of a sub-group of the ACP gene family was found to be developmentally regulated in concert with the storage lipid synthetic phase of seed development. The coding sequence of both B. napus genes are highly homologous (96% and 93% respectively) to a Brassica campestris ACP cDNA sequence, suggesting that they may have evolved from this ancestral gene.