Cloning of acyl-acyl carrier protein (ACP) thioesterase gene from Brassica juncea

Acyl-acyl carrier protein (ACP) thioesterase is the chain-length-determining enzyme in de novo biosynthesis of plant fatty acids. For cloning the gene encoding acyl-ACP thioesterase from Brassica juncea, genomic DNA was used as a template to amplify a 0.7 kb thioesterase fragment in a PCR with the primers designed from the known sequences available in the GenBank. This 0.7 kb fragment was used as a probe to study the expression of the gene in developing seeds and also to screen a genomic library of B. juncea constructed in lambdaEMBL-3 to get the full length of the gene. A 4.0 kb BamHI fragment containing the full gene was finally cloned in a plasmid vector from a recombinant phage clone lambda5.12 after a series of screening, sub-cloning and Southern hybridization.