Genome-wide identification and expression analysis of 3-ketoacyl-CoA synthase gene family in rice (Oryza sativa L.) under cadmium stress

Abstract

3-Ketoacyl-CoA synthase (KCS) is the key rate-limiting enzyme for the synthesis of very long-chain fatty acids (VLCFAs) in plants, which determines the carbon chain length of VLCFAs. However, a comprehensive study of KCSs in <i>Oryza sativa</i> has not been reported yet. In this study, we identified 22 <i>OsKCS</i> genes in rice, which are unevenly distributed on nine chromosomes. The <i>OsKCS</i> gene family is divided into six subclasses. Many <i>cis</i>-acting elements related to plant growth, light, hormone, and stress response were enriched in the promoters of <i>OsKCS</i> genes. Gene duplication played a crucial role in the expansion of the <i>OsKCS</i> gene family and underwent a strong purifying selection. Quantitative Real-time polymerase chain reaction (qRT-PCR) results revealed that most <i>KCS</i> genes are constitutively expressed. We also revealed that <i>KCS</i> genes responded differently to exogenous cadmium stress in <i>japonica</i> and <i>indica</i> background, and the <i>KCS</i> genes with higher expression in leaves and seeds may have functions under cadmium stress. This study provides a basis for further understanding the functions of <i>KCS</i> genes and the biosynthesis of VLCFA in rice.