Abstract: KAR encodes beta-ketoacyl ACP reductase,which catalyzes ketoacyl reduction in fatty acid synthesis.In order to understand the expression characteristics and function of HaKARgene in sunflower,the bioinformatics of HaKARprotein and gene expression pattern were analyzed.It was predicted that the protein encoded by HaKAR1 was basic protein and hydrophilic protein.The secondary structure of the protein encoded by HaKAR1 was mainlyα-helix,and the subcellular localization was predicted in the chloroplast.Phylogenetic analysis showed that HaKAR1 was closely related to Lactuca sativa L.KAR,and the sequence similarity was as high as 90%.The expression pattern analysis of the gene showed that HaKAR1 was highly expressed in sunflower seeds,ligulate flowers and tubular flowers,followed by stems and leaves,but not in roots.The expression of HaKAR1 in both high and low oleic acid sunflower seeds increased at first and then decreased,and then increased again at 7-27 days after flowering.However,the expression level of HaKAR1 in sunflower seeds with low oleic acid was significantly higher than that in sunflower seeds with high oleic acid at 37 days after flowering,which indicated that there might be different expression regulation mechanisms of HaKAR1 in high and low oleic acid sunflower seeds at late development stage.