Wang Yuting, Zhang Hongliang, Wan Chao, He Xian, Huang Jinfeng, Lyu Meiling, Yuan Yuan, Wu Binghua
Ornamental Horticulture Department, College of Horticulture, Fujian Agriculture and Forestry University, No. 15, Shang Xia Dian Road, Cangshan District, Fuzhou 350002, China.
The Fujian Provincial Key Laboratory of Plant Functional Biology, College of Life Sciences, Fujian Agriculture and Forestry University, No. 15, Shang Xia Dian Road, Cangshan District, Fuzhou 350002, China.
Plants (Basel). 2021 Dec 21;11(1):13. doi: 10.3390/plants11010013.
Volatile benzenoid compounds are found in diverse aromatic bouquets emitted by most moth-pollinated flowers. The night-blooming is widely cultivated worldwide in the tropics and subtropics for ornamental and industrial purposes owing to its fragrant flowers. Benzylacetate is a characteristic constituent in jasmine scent which makes up to approximately 20-30% of the total emission in the headspace or extract, but the biosynthesis enzymes and the encoding genes have not yet been described. Here, we identify two cytosolic BAHD acyltransferases specifically expressed in the petals with a positive correlation closely to the emission pattern of the volatile benzenoids. Both JsBEAT1 and JsBEAT2 could use benzylalcohol and acetate-CoA as substrates to make benzylacetate in vitro. The recombinant GST-JsBEAT1 has an estimated apparent of 447.3 μM for benzylalcohol and 546.0 μM for acetate-CoA, whereas in the instance of the His-JsBEAT2, the values are marginally lower, being 278.7 and 317.3 μM, respectively. However, the catalytic reactions by the GST-JsBEAT1 are more efficient than that by the His-JsBEAT2, based on the steady-state parameters. Furthermore, ectopic expression of JsBEAT1 and JsBEAT2 in the transgenic plants, driven by a flower-specific promotor, significantly enhances the biosynthesis of benzylbenzoate and benzylacetate, as well as the total VOCs.
大多数蛾媒花所散发的各种芳香花束中都含有挥发性苯类化合物。夜花因其芬芳的花朵，在热带和亚热带地区广泛种植，用于观赏和工业用途。乙酸苄酯是茉莉花香中的一种特征成分，在顶空或提取物中的总排放量中占比约为20%-30%，但其生物合成酶和编码基因尚未见报道。在此，我们鉴定出两种在花瓣中特异性表达的胞质BAHD酰基转移酶，它们与挥发性苯类化合物的排放模式呈正相关。JsBEAT1和JsBEAT2在体外都可以使用苯甲醇和乙酰辅酶A作为底物来合成乙酸苄酯。重组GST-JsBEAT1对苯甲醇的估计表观Km值为447.3 μM，对乙酰辅酶A的估计表观Km值为546.0 μM，而对于His-JsBEAT2，Km值略低，分别为278.7和317.3 μM。然而，基于稳态动力学参数，GST-JsBEAT1的催化反应比His-JsBEAT2更有效。此外，由花特异性启动子驱动的JsBEAT1和JsBEAT2在转基因植物中的异位表达显著增强了苯甲酸苄酯和乙酸苄酯的生物合成以及总挥发性有机化合物的合成。
