油菜素内酯调控糖代谢增强杏果实抗冷性机理的研究

Apricot fruit is a type of climacteric fruit and post-harvest losses was very important caused by rapid fruit ripening and declining disease resistance. Post-harvest decay and quality deterioration of apricot fruits could be effectively inhibited by cold storage. But chilling injury easily produced as a result of apricot fruits sensitivity to low temperature. The application of cold storage technology on the storage and transportation of apricot fruits was limited by chilling injury incidence. Brassinosteroids（BRs） is endogenous phytohormone, playing pivotal roles in regulating stress responses and plant developmental processes.The effect of 24-Epibrassinolide (EBR) on chilling injury incidence, chilling injury index and storage quality of apricot fruits were systematically studied in this experiment. The effects of EBR on the soluble sugar content, the activities of sugar metabolism, the stability of cell membrane, the antioxidant activity and the key enzymes expression of sugar metabolism in apricot fruit were investigated. The mechanism of enhanced tolerance to low temperature of apricot fruits with EBR treatment by sugar metabolism were clarified. The objective of this study was to improve the protection mechanism of soluble sugar to fruit under low temperature stress, and the other hand, to give theoretical guide for inducing tolerance to low temperature of postharvest fruits by EBR.

杏属于呼吸跃变型果实，采后后熟衰老迅速，抗病能力下降，腐烂损失非常严重。低温冷藏能有效抑制杏果采后腐烂和品质下降, 但杏果对低温环境敏感，在低温下贮藏易引起冷害，严重影响杏的贮藏品质。如何增强杏果实采后对低温的耐受性，控制冷害的发生，已成为杏采后贮运产业中亟需解决的问题。油菜素内酯是一种普遍存在于植物中的天然植物激素，在调节植物的抗逆反应和植物的生长发育进程中起着重要作用。本课题系统研究了24-表油菜素内酯（24-Epibrassinolide, EBR)处理对杏果实冷害发病率、冷害指数和贮藏品质的影响，并通过研究EBR对杏果实可溶性糖含量变化、糖代谢相关酶活性、细胞膜稳定性、抗氧化活性及杏果实糖代谢关键酶基因表达的影响，从糖代谢的角度阐明EBR增强杏果实采后低温耐受性的机理。本课题的研究可完善低温胁迫下可溶性糖对果实的保护机制，并为EBR在采后果实低温适应性诱导方面提供理论基础。

杏属于呼吸跃变型果实，采后后熟衰老迅速，抗病能力下降，腐烂损失非常严重。低温冷藏能有效抑制杏果采后腐烂和品质下降, 但杏果对低温环境敏感，在低温下贮藏易引起冷害，严重影响杏的贮藏品质。如何增强杏果实采后对低温的耐受性，控制冷害的发生，已成为杏采后贮运产业中亟需解决的问题。油菜素内酯是一种普遍存在于植物中的天然植物激素，在调节植物的抗逆反应和植物的生长发育进程中起着重要作用。本课题系统研究了24-表油菜素内酯（24-Epibrassinolide, EBR)处理对杏果实冷害发病率、冷害指数和贮藏品质的影响，并通过研究EBR对杏果实可溶性糖含量变化、糖代谢相关酶活性、细胞膜稳定性、抗氧化活性及杏果实糖代谢关键酶基因表达的影响，从糖代谢的角度阐明EBR增强杏果实采后低温耐受性的机理。. 浓度为0.9 mg/L的EBR有效抑制了杏果实丙二醛、细胞膜透性、失重率的增加和硬度、可溶性固形物、可滴定酸、抗坏血酸的含量下降；明显促进了杏果实SOD、APX和GR活性增加，减缓了POD和CAT活性下降；抑制H2O2、GSH和O2-·含量的增加；EBR处理能明显减轻低温对杏果实细胞结构的破坏，维持了叶绿体、液泡、线粒体、细胞壁等结构的完整性。EBR处理通过提高杏果实AI、NI、SSc、SPS、SDH的酶活性使果糖、葡萄糖、山梨醇含量增加，相关性分析结果表明，果糖、葡萄糖与冷害指数、冷害发病率均有显著相关性。贮藏结束时，EBR处理组杏冷害指数、冷害发病率分别比对照组下降17.50%、24.60%。DEGs的GO分析表明，EBR处理显著影响杏果实碳水化合物代谢过程、多糖分解/代谢过程、生物过程、水解酶活性和分解代谢活性。KEGG的分析表明，苯丙素生物合成、谷胱甘肽代谢、氨基糖和核苷酸糖代谢和亚油酸代谢等代谢显著富集；在对胁迫的响应中，EBR处理诱导的基因主要涉及生长素、乙烯、丝裂原活化蛋白激酶、过氧化物酶、细胞壁、蛋白水解、热休克蛋白和次生代谢物。. 本课题的研究可完善低温胁迫下可溶性糖对果实的保护机制，并为EBR在采后果实低温适应性诱导方面提供理论基础。

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