Molecular cloning and characterization of an acyl-ACP thioesterase gene (AhFatB1) from allotetraploid peanut (Arachis hypogaea L.)

Acyl-acyl carrier protein (ACP) thioesterase is a nuclear encoded plastid localized enzyme which plays an essential role in chain termination during de novo fatty acid synthesis in plant. FatB genes coding for this enzyme from a variety of plant species have been isolated and characterized. However, there are few reports on such genes in peanut ( Arachis hypogaea ), an important edible and oilseed crop. In this study, full-length cDNA of an acyl-acyl carrier protein thioesterase (EC 3.1.2.14), designated as AhFatB1 , was isolated from peanut cDNA libraries. The putative open reading frames consist of 1239 bp with five introns spliced from the corresponding genomic sequence, encoding a 413 amino acid protein, two homologous genes, AhFatB1A and AhFatB1B , with sequence difference at the 5’ non-coding regions were characterized at the nucleotide level from different cultivated peanut genotypes, and the two genes have their origin in different diploid progenitor which was evidenced by the characterization of AhFatB1 genes from Arachis duranensis and Arachis ipaensis , the putative A-genome donor and B-genome donor respectively. AhFatB1 genes are constitutively expressed in peanut tissues and the total FatB1 transcript accumulations are temporally regulated during peanut seed development. Keywords: Peanut thioesterase, palmitic acid oilseed