Variations Of The Glycosidically Aroma Precursors Induced By Pathogenic Fungi Infection In Leaves Of Camellia Sinensis

Glycosidic aroma precursors are a kind of secondary metabolites of in plants during growth, which are bounded by a sugar part and a volatile aglycone part. There isn’t volatility of such compounds in themselves and they can be stored in plants abundantly. The glycosides will be hydrolyzed by enzymes, releasing volatile aglycones and demonstrating the smell which can resistant to insect pests and pathogens when the plants come across the stress of non-biological environmental factors or invasion of pests and pathogenic fungi. There are vast area of tea plantations in our country, and the diseases of tea occur frequently, they can have a significant impact on the quality of tea. Although the defense mechanism of glycosidic aroma precursors of Camellia sinensis （L.）O. Kuntze against fungal pathogens hasn’t been fully understood at present.In this paper, N-methyl-bis (trifluoroacetamide) is used to derive glycosidic aroma precursors. The derivation conditions were optimized from temperature and time during the process of derivation reaction, and it showed that reacting at60oC for50min was best. Then the GC-ECD method for the determination was compared with GC-FID and GC-MS method. The results showed that this derivation reaction combining GC-ECD detection could be used for trace analysis of glucosides due to its high sensitivity, great repeatability and stability.The fresh leaves of Camellia sinensis（L.）O. Kuntze were from two parts, one part were cultured by MS solid medium, then infected by pathogenic fungi in the lab the other were cultured and infected in tea garden naturally. The changes of glycosidic aroma precursors in tea leaves which were infected were studied by GC-ECD detection after extracted and MBTFAderivation.The tea leaves can be in the survival of MS solid medium and keep living about two weeks after picked from tea bushes. These leaves could be infected by pathogenic fungi successfully under the strict control of temperature and humidity.The total content of the six glycosidic aroma precursors in the healthy Duokang xiang was highest compared with Fushe zao, Nongmen xiang, Shucha in the tea garden in autumn. Both benzyl alcohol-β-D-glucoside and benzyl-primeveroside were higher than the other glycosides of these four tea varieties.The total content of the six glycosidic aroma precursors in the first, the third and the fourth leaf of Fushe zao reduced obviously after infected, while the second leaves, increased. All of these leaves were picked from tea garden at summer, cultured in MS solid medium.The tea leaves of Fushe zao, Nongmen xiang, Shucha zao, Duokang xiang were infected naturally in the tea garden in autumn. the content of Z-3-hexenol-β-D-glucoside increased in the tea leaves of Fushe zao, while the other glycosides were significantly reduced the content of benzyl prim increased in the tea leaves of Nongmen xiang, and the total content of the six glycosides was increased too. the content of benzyl-β-D-glucoside and linalool oxide-β-D-glucoside increased respectively while the others, decreased in the tea leaves of Shucha zao the content of the oxidation of linalool-β-D-glucoside increased slightly while others, decreased significantly in the tea leaves of Duokang xiang. All in all, both the content of benzyl prim and the total content of the six glycosides in these tea varieties decreased after infected by pathogenic fungi expect Nongmen xiang.The content of glycosides in the fresh tea leaves of Shucha zao which were infected naturally in the tea garden in autumn was lower than control leaves at the beginning, then it increased when the area of disease lesion became larger, it turned to be highest when the lesion area was of317-335mm~2.