Molecular Cloning, Characterization and Expression Analysis of B-Ketoacyl-ACP Synthetase II Gene from Peanut

β-ketoacyl-ACP synthetase II (KAS II) which catalyzes the elongation of 16:0-ACP to 18:0-ACP, determines the ratio of palmitic acid (16:0) to stearic acid (18:0). Using Rapid Amplification of cDNA Ends (RACE) and a peanut cDNA library we had previously constructed, we isolated a 1867bp cDNA of the KAS II gene containing a 1212bp complete open reading fragment (ORF). Sequence analysis revealed that peanut KAS II had a high level of nucleotide and amino acid sequence homology to KAS II from other plants. Phylogenetic analysis showed that KAS II from plants, bacteria and virus were grouped into different clades respectively suggesting the independent evolution of KAS II from different sources. Characteristics of the deduced protein were predicted and analyzed using bioinformatic methods. The protein was predicted as stable and hydrophobic with molecular weight of 43181.4 and theoretical PI of 5.69. Expression analysis by real-time PCR indicated that expression levels of KAS II gene were markedly distinct in different peanut tissues and varieties. The expression analysis in this study combined with existing researches suggested KAS II may be involved in the regulation of plant growth and development.