UDP-glucosyltransferase PpUGT85A2 controls volatile glycosylation in peach
UDP-glucosyltransferase PpUGT85A2 controls volatile glycosylation in peach
复制标题
UDP-葡萄糖基转移酶 PpUGT85A2 控制桃子中的挥发性糖基化
DOI：
10.1093/jxb/ery419
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发表时间：
2019-01-30
影响因子：
6.9
通讯作者：
Chen, Kunsong
中科院分区：
文献类型：
--
作者：
Wu, Boping;Cao, Xiangmei;Chen, Kunsong
单萜芳樟醇是桃(Prunus Perica)果实香味和风味的主要贡献者。它在水果成熟期间积累，其中高达40%的化合物以非挥发性糖基化形式存在，在品尝过程中通过逆鼻感知影响风味质量和消费者感知。尽管这种固存对风味很重要，但在桃中还没有鉴定出负责芳樟醇糖基化的UDP-糖基转移酶(UGT)。利用RNA测序技术分析了桃果实成熟过程中UGT基因在不同品种间的表达，并筛选出与芳樟酰-β-D-葡萄糖苷相关的转录本进行功能分析。R，S-芳樟醇的外消旋混合物对PpUGT85A2有动力学拆分作用，对S-(+)-芳樟醇有轻微的选择性。PpUGT85A2在体外可以催化合成芳樟基-β-D-葡萄糖苷，但在不同的底物中，PpUGT85A2的酶活性不是最高的。检测PpUGT85A2在胞浆和胞核的亚细胞定位。芳樟醇处理促进了PpUGT85A2的表达和芳樟醇-β-d-葡萄糖苷的产生。在桃树果实中瞬时表达，在烟草和拟南芥中稳定过表达，导致芳樟酰-β-D-葡萄糖苷在体内显著积累。综上所述，结果表明PpUGT85A2的表达是预测芳樟醇-β-D-葡萄糖苷含量的主要控制点。
The monoterpene linalool is a major contributor to aroma and flavor in peach (Prunus persica) fruit. It accumulates during fruit ripening, where up to similar to 40% of the compound is present in a non-volatile glycosylated form, which affects flavor quality and consumer perception by retronasal perception during tasting. Despite the importance of this sequestration to flavor, the UDP-glycosyltransferase (UGT) responsible for linalool glycosylation has not been identified in peach. UGT gene expression during peach fruit ripening and among different peach cultivars was analyzed using RNA sequencing, and transcripts correlated with linalyl-beta-D-glucoside were selected as candidates for functional analysis. Kinetic resolution of a racemic mixture of R, S-linalool was shown for PpUGT85A2, with a slight preference for S-(+)-linalool. PpUGT85A2 was shown to catalyze synthesis of linalyl-beta-D-glucoside in vitro, although it did not exhibit the highest enzyme activity between tested substrates. Subcellular localization of PpUGT85A2 in the cytoplasm and nucleus was detected. Application of linalool to peach leaf disks promoted PpUGT85A2 expression and linalyl-beta-d-glucoside generation. Transient expression in peach fruit and stable overexpression in tobacco and Arabidopsis resulted in significant accumulation of linalyl-beta-D-glucoside in vivo. Taken together, the results indicate that PpUGT85A2 expression is a major control point predicting linalyl-beta-D-glucoside content.