Identification and Expression Analysis of WSD (Wax Ester Synthase/Diacylglycerol Acyltransferase) Gene Family in Apple

Wax ester synthase/diacylglycerol acyltransferase (WS/DGAT), or WSD, is a group of key enzymes that catalyze the biosynthesis of triacylglycerols in plants and other organisms; however, the WSD members remain unclear in apples (Malus domestica). To investigate the function of MdWSD family genes in wax biosynthesis and stress resistance, we analyzed the structural characteristics and expression patterns of the MdWSD genes. Based on the local BLAST database and the Pfam database, a total of seven WSD gene family members in the whole genome of apple were identified. The secondary structure of the protein was mainly random coil, followed by alpha helix, and the smallest proportion was beta turn. The WSD proteins were localized in the nucleus and cytoplasm, which is consistent with the characteristics of wax synthesis. Chromosome mapping showed that the seven MdWSD genes were located on five chromosomes. In addition, the results of real-time fluorescent quantitative polymerase chain reaction showed that MdWSD members responded to abiotic stresses such as drought and salt stress, indicating that the MdWSD family is related to abiotic stresses.