柑橘采后贮藏过程中CsMYB30基因调控果皮蜡质合成的分子机制

With the development of social economy, future technologies will be characterized by non-toxic additives as consumers pursue green, high-quality fruit and vegetable products. Wax plays important roles during fruit postharvest storage. Therefore, it is promising to open up a way for keeping fruits fresh by improving wax characteristics. Our previous study found that transcription factor CsMYB30 showed strong correlations with the wax synthesis related genes, wax contents and storage performance of citrus fruits, which suggested that the gene might regulate the process of wax formation in citrus fruits. In this proposal, we plan to over-express and silence CsMYB in precocious Hongkong kumquat (Fortunella hindsii Swingle), to investigate the functions of CsMYB in transcriptional activation of cuticular wax biosynthesis. Meanwhile, the downstream target genes of CsMYB will be identified by using ChIP-Seq and yeast one-hybrid technologies. Finally, to search methods for improving storage performance by enhancing wax synthesis through CsMYB30 regulation, the effects of environmental factors on expression pattern of CsMYB30, synthesis of fruits wax and storage performance of Hongkong kumquat fruits will be studied. Expected results from this work will help clarify regulatory mechanism of the CsMYB genes in wax formation of citrus fruit, and consequently provide the theoretical basis for development of fresh-keeping technology in fruits storage.

探索绿色、安全的果蔬贮藏保鲜新技术是食品科学领域的重大课题。柑橘果皮蜡质层是果实对外物质交换的界面，也是其抵御外界入侵的天然物理屏障，在柑橘贮藏保鲜过程中发挥着重要作用。在前期对柑橘果皮蜡质的研究中，申请人发现转录因子CsMYB30与蜡质合成基因的表达、表皮蜡质含量和果实贮藏性能密切相关，表明该基因具有调控柑橘果面蜡质合成的功能，但尚缺乏直接的实验证据，具体的调控机制也有待深入研究。基于此，本项目拟以短童期的山金柑为材料，通过抑制和超表达CsMYB30，系统验证该基因对蜡质的调控作用；并通过ChIP-Seq和酵母单杂技术筛选CsMYB30所调控的下游靶基因，探明其调控蜡质的分子机制；自此基础上，探明贮藏环境因素对山金柑果实CsMYB30表达的影响规律，探讨通过调控CsMYB30促进蜡质合成、提高贮藏性能的方法和途径。研究结果将完善柑橘果皮蜡质的调控机制，并为柑橘保鲜新技术的开发提供理论依据

果蔬表皮蜡质层是果实对外物质交换的界面，也是其抵御外界入侵的天然物理屏障，在果蔬贮藏保鲜过程中发挥着重要作用。项目基于前期发现的柑橘转录因子CsMYB30与蜡质的紧密相关性，系统研究了CsMYB30超表达对拟南芥抗性、蜡质和相关代谢的影响与作用机理。研究发现拟南芥中超表达柑橘CsMYB30基因提高了对干旱和盐胁迫的耐受性；进一步的研究表明，CsMYB30超表达株系的表皮通透性降低，表皮蜡质总量增加、蜡质晶型发生显著变化。通过基因表达分析、蜡质成分分析、蜡质合成前体代谢物分析等，发现大多数与蜡合成途径相关的基因在转录水平上调，蜡质相关代谢物的含量发现了显著变化，可推断CsMYB30通过上调蜡合成相关基因（例如KCSs，CER1等）的表达来增强蜡合成代谢通路，从而改善了非生物胁迫耐受性。此外，研究发现了柑橘转录因子CsMYB30对类黄酮物质代谢的负调控作用，这为柑橘果实品质调控提供了新的线索。在项目主体完成的基础上，进一步探究了细胞壁完整性对食品采后生理的重要潜在作用，丰富和完善了细胞壁-蜡质层在食品采后保鲜中的重要作用，为认知食品采后生理与保鲜机理提供了新的视角。