The Clone Of MdCER4, MdWSD1, MdMAH1 And Their Response To Ethylene Regulation

The cuticular wax synthesis includes acyl reduction pathway and decarbonylation pathway. The genes of CER4 and WSD1 were involved in the acyl reduction pathway, and the gene of MAH1 was involved in the decarbonylation pathway. In this paper, the Starkring(Malus domestica Borkh c.v. Starkring) was used as materials, to clone the genes of MdWSD1, MdMAH1 and MdCER4, and analysis their biological function. The expression modes of MdWSD1, MdMAH1 and MdCER4, and the cuticular wax composition and content were also studied during fruit development and storage period.The effects of ethrel and 1-MCP to MdWSD1, MdMAH1 and MdCER4 were also studied during preharvest and postharvest. The main results were as follows:1. The genes of MdWSD1, MdMAH1 and MdCER4 were cloned and their length are578 bp, 500 bp and 509 bp respectively, then the whole sequences were obtained by aligned with the apple GeneBank. The analysis of biological function showed that the sequence length of MdWSD1 gene was 2622 bp, the protein contained two protein conservative districts which named WES-acyl transf and acyl-WS-DGAT, and the former encoded acyl-Co A transferase, the latter encoded acyl transferase. The sequence length of MdMAH1 gene was 2148 bp, the protein contained four protein conservative districts which named PLN03195, P450, Cypx and PTZ00404, and the first encoded fatty acid-ω-desaturase, others were associated with cytochrome P450. The sequence length of MdCER4 gene was 1620 bp, the protein contained two protein conservative districts which named FAR-N_SDR_e and PLN02996, and they encoded acyl-coenzyme A reductase.2. In apple development period, the mass density of fruit cuticular wax increased gradually during 60 d~7 d, and then decreased rapidly during 7 d~0 d preharvest, it was consistent with the relative expression change of MdWSD1 during development period.The content of ester was significantly decreased during 7 d~0 d preharvest, it indicated that MdWSD1 gene might be associated with ester synthesis. In apple storage period, the mass density of cuticular wax increased gradually. The ester and alcohol content increased significantly during 0 d~120 d postharvest. The expression of MdWSD1, MdMAH1 and MdCER4 were at the relative high level during 30 d~90 d postharvest, it was consistent with the content change of ester and alcohol. The results indicated that the cuticular wax content was affected by MdWSD1, MdMAH1 and MdCER4 regulated the ester and alcohol synthesis.3. The analysis of the effects of ethrel and 1-MCP to the expression of wax synthesisgenes during preharvest showed that the MdWSD1 gene was positive regulated by ethylene,and the regulation of MdMAH1 and MdCER4 genes by ethylene hadn’t obvious regular.Compared with CK, ethrel promoted the increase of ester, aldehyde, alkane and alcohol content, and they were inhibited by 1-MCP. It was consistent with the effects of these three treatments to the mass density of apple cuticular wax.4. The analysis of the effects of ethrel and 1-MCP to the expression of wax synthesis genes during postharvest showed that MdWSD1 and MdCER4 genes were positive regulated by ethylene, and the regulation of MdMAH1 gene by ethylene hadn’t obvious regular. Compared with CK, ethrel promoted the expression of MdWSD1 and MdCER4,and the increase of cuticular wax content, and they were inhibited by 1-MCP. The results indicated that the content of ester and alcohol were increased by ethylene positive regulated the expression of MdWSD1 and MdCER4 genes.