Characterization of Five Putative Acyl Carrier Protein (ACP) Isoforms from Developing Seeds of Arachis hypogaea L

Five putative acyl carrier protein (ACP) cDNAs were isolated from developing peanut seeds by searching ESTs of a peanut immature-seed cDNA library and PCR-based cloning. Five peanut ACPs contained a strictly conserved Ser residue in the Asp-Ser-Leu (DSL) motif, which is an important characteristic of ACPs in plants and bacteria. Three AhACPs, AhACP1, AhACP4, AhACP5, were predicted to be located in chloroplast, while two AhACPs, AhACP2 and AhACP3, in mitochondria. Comparison of genomic DNA and cDNA sequences demonstrated three chloroplast ACPs (cpACPs) comprising of four exons and three introns while two mitochondrial ACPs (mtACPs) contained two exons and one intron. More than two homologs of each AhACP were expressed in developing peanut seeds. Most homologs were verified by corresponding genomic DNA sequences. Semi-quantitative RT-PCR analysis suggested AhACP1 was a seed-predominant ACP isoform. AhACP4 and AhACP5 showed same mRNA profile in different organs and during seed development. Two mtACPs expressed highly in peanut flower tissue which was distinct from three cpACPs.