Apple cuticular wax can protect plants from environmental stress, determine fruit luster and improve postharvest fruit storage quality. In recent years, dry weather, soil salinization and adverse environmental conditions have led to declines in apple fruit quality. However, few studies have reported the molecular mechanisms of apple cuticular wax biosynthesis. In this study, we identified a long-chain acyl-CoA synthetase MdLACS2 gene from apple. The MdLACS2 protein contained an AMP-binding domain and demonstrated long-chain acyl-CoA synthetase activity. MdLACS2 transgenic Arabidopsis exhibited reductions in epidermal permeability and water loss; change in the expression of genes related to cuticular wax biosynthesis, transport and transcriptional regulation; and differences in the composition and ultrastructure of cuticular wax. Moreover, the accumulation of cuticular wax enhanced the resistance of MdLACS2 transgenic plants to drought and salt stress. The main protein functional interaction networks of LACS2 were predicted, revealing a preliminary molecular regulation pathway for MdLACS2-mediated wax biosynthesis in apple. Our study provides candidate genes for breeding apple varieties and rootstocks with better fruit quality and higher stress resistance.

中文翻译：

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苹果长链酰基辅酶A合成酶2基因通过调节表皮蜡的积累来增强植物对非生物胁迫的抗性。

苹果皮表皮蜡可以保护植物免受环境压力，确定果实的光泽，并改善采后的果实贮藏品质。近年来，干燥的天气，土壤盐碱化和不利的环境条件导致苹果果实品质下降。然而，很少有研究报道苹果表皮蜡生物合成的分子机制。在这项研究中，我们从苹果中鉴定了一个长链酰基辅酶A合成酶MdLACS2基因。MdLACS2蛋白包含AMP结合域，并显示出长链酰基辅酶A合成酶活性。MdLACS2转基因拟南芥表现出表皮渗透性和水分流失的减少；与表皮蜡生物合成，转运和转录调控有关的基因表达的变化；表皮蜡的组成和超微结构的差异。此外，表皮蜡的积累增强了MdLACS2转基因植物对干旱和盐胁迫的抗性。预测了LACS2的主要蛋白质功能相互作用网络，揭示了MdLACS2介导的苹果蜡生物合成的初步分子调控途径。我们的研究提供了具有更好果实品质和更高抗逆性的苹果品种和砧木育种候选基因。