UGT74AF3 enzymes specifically catalyze the glucosylation of 4-hydroxy-2,5-dimethylfuran-3(2H)-one,an important volatile compound in Camellia sinensis

4-Hydroxy-2,5-dimethylfuran-3(2H)-one(HDMF)is an important odorant in some fruits,and is proposed to play a crucial role in the caramel-like notes of some teas.However,its biosynthesis and metabolism in tea plants are still unknown.Here,HDMF glucoside was unambiguously identified as a native metabolite in tea plants.A novel glucosyltransferase UGT74AF3a and its allelic protein UGT74AF3b specifically catalyzed the glucosylation of HDMF and the commercially important structural homologues 2(or 5)-ethyl-4-hydroxy-5(or 2)-methylfuran-3(2H)-one(EHMF)and 4-hydroxy-5-methylfuran-3(2H)-one(HMF)to their correspondingβ-D-glucosides.Site-directed mutagenesis of UGT74AF3b to introduce a single A456V mutation resulted in improved HDMF and EHMF glucosylation activity and affected the sugar donor preference compared with that of the wild-type control enzyme.The accumulation of HDMF glucoside was consistent with the transcript levels of UGT74AF3 in different tea cultivars.In addition,transient UGT74AF3a overexpression in tobacco significantly increased the HDMF glucoside contents,and downregulation of UGT74AF3 transcripts in tea leaves significantly reduced the concentration of HDMF glucoside compared with the levels in the controls.The identification of HDMF glucoside in the tea plant and the discovery of a novel-specific UDP-glucose:HDMF glucosyltransferase in tea plants provide the foundation for improvement of tea flavor and the biotechnological production of HDMF glucoside.

The Agricultural Technology for Manuring and Sowing Simultaneously Applied to Summer Corn "Jinzhengda"

[Objective] The aim was to get a high yield and simplify fertilization of summer corn in moisture soils in the east of Henan province. [Method] Effects of slow-release fertilizers special for summer corn on its yield, economic benefits and resistance. [Result] By the slow-release fertilizers containing 45% slow-release nitrogen, thousand-kernel weight and the number of ear went up by 28 g and 16 kernels, respectively. Slow-release fertilizers advanced nutrient uptake by summer corns and kept soil nitrogen balanced. In comparison to local fertilization approach, corn yield grew by 13.5% and net profit went up by 1 920 yuan/hm^2 by same-term application technique of seed ＆ slow-release fertilizer in comparison to local methods. In comparison to normal fertilizers containing the same-quantity nutrients, corn yield grew by 10.3% and net profit by 1 215 yuan/hm^2. [Conclusion] The research provides references for slow-release fertilizer promotion in production of corn in Zhoukou and innovation and integration between agricultural machines and techniques.