桃果实结合态香气物质的形成及调控机制

Aroma-related volatiles play an important role in determining characteristic flavor quality, and have received a great deal of attention for fruit quality biology research. Aroma is produced by free volatiles that are released from fruit tissue. In plants, volatiles are stored as bound volatiles, which could be deconjugated into free volatiles, therefore, influence flavor quality. Peach is an economically important fruit tree both for China and the world, whose aroma quality have been intensively studied. However, bound volatiles have not been identified in peach fruit. Moreover, genes responsible for bound volatiles biosynthesis and their regulation mechanism were rarely investigated. By using peach fruit at different ripening stages as materials, the present project will combine technologies, including chaomatography, physiology and biochemistry, molecular biology, to identify bound volatiles and their biosynthesis related UDP-glucosyltransferase (UGT) family members. Furthermore, UGTs function will be confirmed by transient assay and transgenic study. The results of present project will provide new insight in peach fruit volatile formation and new scientific evidence for improving fruit aroma quality.

香气物质是果实特征品质的重要组成，已经成为发育与品质研究的新主题。游离态香气物质从果实中释放形成香气，贮存的结合态香气物质可以转化为游离态进而影响感官品质。有关结合态香气物质的研究近年来开始受到关注。桃是我国及世界性重要果树，已有香气品质报道主要集中在挥发性的游离态香气物质，尚未见到结合态香气物质的研究，其合成相关的基因和调控途径也不清楚。本申请项目以不同生长发育阶段的桃果实为材料，结合农艺等措施，围绕结合态香气物质的形成与调控机制，采用色/质谱精确检测体系，分析影响果实品质的重要结合态香气物质，应用转录组和原核表达等技术手段，筛选结合态香气物质形成相关的尿嘧啶核苷二磷酸-糖基转移酶（UGT）家族成员，使用异源转基因和同源瞬时表达体系，验证候选UGT基因的生物学功能。研究成果可为香气物质代谢研究提供新内涵，也可为改善果实品质实践提供新路径。

芳香物质是果实特征品质的重要组成，已经成为发育与品质研究的新主题。游离态芳香物质从果实中释放形成香味，贮存的结合态芳香物质可以转化为游离态进而影响感官品质。有关结合态芳香物质的研究近年来开始受到关注。桃是我国及世界性重要果树，已有芳香品质报道主要集中在挥发性的游离态芳香物质，尚未见到结合态芳香物质的研究，其合成相关的基因和调控途径也不清楚。本项目以不同生长发育阶段的桃果实为材料，结合农艺等措施，围绕结合态芳香物质的形成与调控机制，采用色/质谱精确检测体系，明确了桃果实生长发育过程中结合态芳香物质的变化规律，应用转录组和原核表达等技术手段，筛选获得了结合态芳香物质形成相关的尿嘧啶核苷二磷酸-糖基转移酶（UGT）家族成员，通过采用异源转基因和同源瞬时表达体系，鉴别出调控结合态芳樟醇、苯乙醇和水杨酸甲酯等结合态芳香物质合成的PpUGT85A2、PpUGT74F2等家族成员，利用桃果实的同源瞬时表达技术，并结合模式材料的转基因证据验证了上述UGT调控结合态芳香物质的功能。研究成果揭示了果实芳香物质代谢调控的新机制，鉴别出的调控结合态芳香物质的PpUGT基因家族成员，可为改善果实风味品质提供依据，同时研究发现对于理解植物进化也具有参考意义。