Two types of cDNA (named AhDGAT3A and AhDGAT3B) encoding diacylglycerol acyltransferase were isolated from the developing seeds of Arachis hypogaea Luhua 14 by RT-PCR.The similarities of the nucleotide and putative amino acid sequences of the two genes were 96% and 94%,and further analyses of AhDGAT3A were performed from different aspects:(1)By semi-quantitative RT-PCR analysis,it was showed that the transcription of AhDGAT3A mRNA was detectable in all organs analyzed,and the expression level of this gene was the highest in flower,and the lowest in stem;in seed,the expression level of this gene at the developmental stage of 60 d after pegging was higher than that at the other developing stages.(2)Using the method of chromosome walking,a 1 588 bp length of DNA fragment from 5′ upstream regulation region of AhDGAT3A was cloned,and the cis-acting elements were analyzed with the online software.It was found that in the promoter region,additionally,the core elements,there were several other pupative regulation elements which involved in the expression in pollens,the responsiveness of light and stress.(3)The investigation of the crude lipid content and the main fatty acids content was found that,due to the influence of homologous co-suppression,the seeds in all transgenic tobacco lines overexpressing AhDGAT3A contain less crude lipid and main fatty acids than those in controls.