Genome-Wide Identification of Peanut Genes Reveals That and Are Involved in Regulating VLCFA Contents in Seeds.

The peanut ( L.) is an important oilseed crop worldwide. Compared to other common edible vegetable oils, peanut oil contains a higher content of saturated fatty acids (SFAs), approximately 20-40% of which are very long chain fatty acids (VLCFAs). To understand the basis for this oil profile, we interrogated genes for peanut β-ketoacyl-CoA synthase (KCS), which is known to be a key enzyme in VLCFA biosynthesis. A total of 30 genes were identified in the assembled genome of the peanut. Based on transcriptome data, nine genes with high expression levels in developing seeds were cloned and expressed in yeast. All these AhKCSs could produce VLCFAs but result in different profiles, indicating that the AhKCSs catalyzed fatty acid elongation with different substrate specificities. Expression level analysis of these nine genes was performed in developing seeds from six peanut germplasm lines with different VLCFA contents. Among these genes, the expression levels of or were, 4-10-fold higher than that of any other . However, only the expression levels of and were significantly and positively correlated with the VLCFA content, suggesting that AhKCS1 and AhKCS28 were involved in the regulation of VLCFA content in the peanut seed. Further subcellular localization analysis indicated that AhKCS1 and AhKCS28 were located at the endoplasmic reticulum (ER). Overexpression of or in increased the contents of VLCFAs in the seed, especially for very long chain saturated fatty acids (VLCSFAs). Taken together, this study suggests that and could be key genes in regulating VLCFA biosynthesis in the seed, which could be applied to improve the health-promoting and nutritional qualities of the peanut.