Zhejiang Key Laboratory of Horticultural Crop Quality Improvement, Zhejiang University, Zijingang Campus, Hangzhou 310058, China.
Key Laboratory of Quality and Safety Control for Subtropical Fruit and Vegetable, Ministry of Agriculture and Rural Affairs, College of Horticulture Science, Zhejiang A&F University, Hangzhou 311300, China.
Plant Physiol. 2024 Oct 1;196(2):1444-1459. doi: 10.1093/plphys/kiae423.
Benzaldehyde (BAld) is one of the most widely distributed volatiles that contributes to flavor and defense in plants. Plants regulate BAld levels through various pathways, including biosynthesis from trans-cinnamic acid (free BAld), release from hydrolysis of glycoside precursors (BAld-H) via multiple enzymatic action steps, and conversion into downstream chemicals. Here, we show that BAld-H content in peach (Prunus persica) fruit is up to 100-fold higher than that of free BAld. By integrating transcriptome, metabolomic, and biochemical approaches, we identified glycoside hydrolase PpGH28BG1 as being involved in the production of BAld-H through the hydrolysis of glycoside precursors. Overexpressing and silencing of PpGH28BG1 significantly altered BAld-H content in peach fruit. Transgenic tomatoes heterologously expressing PpGH28BG1 exhibited a decrease in BAld-H content and an increase in SA accumulation, while maintaining fruit weight, pigmentation, and ethylene production. These transgenic tomato fruits displayed enhanced immunity against Botrytis cinerea compared to wild type (WT). Induced expression of PpGH28BG1 and increased SA content were also observed in peach fruit when exposed to Monilinia fructicola infection. Additionally, elevated expression of PpGH28BG1 promoted fruit softening in transgenic tomatoes, resulting in a significantly increased emission of BAld compared to WT. Most untrained taste panelists preferred the transgenic tomatoes over WT fruit. Our study suggests that it is feasible to enhance aroma and immunity in fruit through metabolic engineering of PpGH28BG1 without causing visible changes in the fruit ripening process.
苯甲醛（Benzaldehyde，BAld）是分布最广泛的挥发性物质之一，它有助于植物的风味和防御。植物通过多种途径调节 BAld 水平，包括从反式肉桂酸（游离 BAld）合成、通过多种酶促作用步骤从糖苷前体水解（BAld-H）释放，以及转化为下游化学物质。在这里，我们表明桃（Prunus persica）果实中的 BAld-H 含量比游离 BAld 高 100 倍。通过整合转录组、代谢组和生化方法，我们鉴定了糖苷水解酶 PpGH28BG1 通过水解糖苷前体参与 BAld-H 的产生。过表达和沉默 PpGH28BG1 显著改变了桃果实中的 BAld-H 含量。异源表达 PpGH28BG1 的转基因番茄表现出 BAld-H 含量降低和 SA 积累增加，同时保持果实重量、色素沉着和乙烯产生不变。与野生型（WT）相比，这些转基因番茄果实对灰葡萄孢（Botrytis cinerea）的免疫力增强。当桃果实受到链格孢菌（Monilinia fructicola）感染时，也观察到 PpGH28BG1 的诱导表达和 SA 含量增加。此外，在转基因番茄中过表达 PpGH28BG1 促进了果实软化，导致与 WT 相比，BAld 的排放量显著增加。大多数未经训练的味觉品尝者更喜欢转基因番茄果实而不是 WT 果实。我们的研究表明，通过代谢工程 PpGH28BG1 增强果实香气和免疫力是可行的，而不会对果实成熟过程造成明显变化。
