ATP柠檬酸裂解酶(ACL)催化柠檬酸生成草酰乙酸和乙酰辅酶A，是联系糖分、有机酸、脂肪酸、类黄酮和类异戊二烯类等物质的桥梁。前期研究证实柑橘果实中存在ACL，并参与柠檬酸降解，但是其活性变化对柑橘果实糖、酸、类异戊二烯等物质，即果实风味、着色和香气等品质的影响如何，自身又受哪些因素调控，目前均不清楚。本项目拟通过测定不同果实发育成熟过程中ACL活性和糖、酸等代谢物质的含量，明确ACL和果实内在品质相关代谢物质变化的关系；通过注射羟基柠檬酸（ACL抑制剂）和转基因试验，验证ACL在果实内在品质相关代谢物质积累中的作用；通过愈伤组织体外培养和田间遮光处理试验，明确不同环境条件对ACL活性的影响；通过转录组测序，解析ACL调控相关代谢物质积累的分子机制。本项目最终确定柑橘ACL在柑橘果实内在品质形成中的作用和对应的调控机制，其结果无疑对柑橘果实品质形成及调控措施研发具有重要的理论和实践意义。

It is very important to investigate the key point for the formation of fruit quality. ATP-citrate lyase (ACL)，catalyzing citrate into oxaloacetate and acetyl-CoA, is a cross-link among a diverse set of phytochemicals including carbohydrates, organic acids, isoprenoids, fatty acids, flavonoids, and so on. Although the previous researches in citrus confirmed that fruit has ACL activity and ACL participates in citrate utilization during fruit ripening, the effect of ACL on the accumulation of sugar, citrate, et al., and the factors affecting ACL are still not clear. In the present proposal, we will investigate the possible relation between the ACL activity and the formation of fruit quality by analyzing the ACL activity and the contents of sugar, citrate, isoprenoids, and et al. in different cultivars’ fruits. This role of ACL in fruit quality formation will be confirmed by hydroxycitrate injection or transgenic experiment with RNAi vector or overexpression vectors. Moreover, we will explore the underlying mechanism by RNA-seq technique and investigate the effect of different environmental factors on the ACL activity by using in vitro tissue culture with the explant of ‘Anliu’ orange callus and by using the field shading treatment. Taken together, the objective of this proposal will identify the role of ACL in the fruit internal quality formation, decipher the possible mechanism underlying the ACL-regulating fruit quality formation and the effect of different environmental factors on the ACL activity, which definitely provide a great theoretical and practical significance for the regulation of citrus fruit quality.