Laboratory of Fruit Quality Biology/Zhejiang Provincial Key Laboratory of Horticultural Plant Integrative Biology , Zhejiang University , Zijingang Campus , Hangzhou 310058 , China.
Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences , Sichuan University , Chengdu 610065 , China.
J Agric Food Chem. 2019 May 8;67(18):5189-5196. doi: 10.1021/acs.jafc.9b01166. Epub 2019 Apr 24.
Peach fruit volatile acetate esters impact consumer sensory preference and contribute to defense against biotic stresses. Previous studies showed that alcohol acyltransferase (AAT) family PpAAT1 is correlated with volatile ester formation in peach fruits. However, fruits also contain carboxylesterase (CXE) enzymes that hydrolyze esters. The functions of this family with regard to volatile ester content has not been explored. Here, we observed that content of acetate ester was negatively correlated with expression of PpCXE1. Recombinant PpCXE1 protein exhibited hydrolytic activity toward acetate esters present in peach fruit. Kinetic analysis showed that PpCXE1 showed the highest catalytic activity toward E-2-hexenyl acetate. Subcellular localization demonstrated that PpCXE1 is present in the cytoplasm. Transient expression in peach fruit and stable overexpression in tomato fruit resulted in significant reduction of volatile esters in vivo. Taken together, the results indicate that PpCXE1 expression is associated with catabolism of volatile acetate esters in peach fruit.
桃果实挥发性醋酸酯影响消费者的感官偏好，并有助于抵御生物胁迫。先前的研究表明，醇酰基转移酶（AAT）家族 PpAAT1 与桃果实中挥发性酯的形成有关。然而，果实中还含有羧酸酯酶（CXE），能够水解酯类。关于该家族对挥发性酯含量的功能尚未得到探索。在这里，我们观察到醋酸酯的含量与 PpCXE1 的表达呈负相关。重组 PpCXE1 蛋白对桃果实中存在的醋酸酯表现出水解活性。动力学分析表明，PpCXE1 对 E-2-己烯基醋酸酯表现出最高的催化活性。亚细胞定位表明 PpCXE1 存在于细胞质中。在桃果实中的瞬时表达和在番茄果实中的稳定过表达导致体内挥发性酯的显著减少。综上所述，结果表明 PpCXE1 的表达与桃果实中挥发性醋酸酯的分解代谢有关。
