Genetic analyses of ancient tea trees provide insights into the breeding history and dissemination of Chinese Assam tea(Camellia sinensis var.assamica)

Chinese Assam tea(Camellia sinensis var.assamica)is an important tea crop with a long history of cultivation in Yunnan,China.Despite its potential value as a genetic resource,its genetic diversity and domestication/breeding history remain unclear.To address this issue,we genotyped 469 ancient tea plant trees representing 26 C.sinensis var.assamica populations,plus two of its wild relatives(six and three populations of C.taliensis and C.crassicolumna,respectively)using 16 nuclear microsatellite loci.Results showed that Chinese Assam tea has a relatively high,but comparatively lower gene diversity(H_(S)=0.638)than the wild relative C.crassicolumna(H_S=0.658).Clustering in STRUCTURE indicated that Chinese Assam tea and its two wild relatives formed distinct genetic groups,with considerable interspecific introgression.The Chinese Assam tea accessions clustered into three gene pools,corresponding well with their geographic distribution.However,New Hybrids analysis indicated that 68.48%of ancient Chinese Assam tea plants from Xishuangbanna were genetic intermediates between the Puer and Lincang gene pools.In addition,10%of the ancient Chinese Assam tea individuals were found to be hybrids between Chinese Assam tea and C.taliensis.Our results suggest that Chinese Assam tea was domesticated separately in three gene pools(Puer,Lincang and Xishuangbanna)in the Mekong River valley and that the hybrids were subsequently selected during the domestication process.Although the domestication history of Chinese Assam tea in southwestern Yunnan remains complex,our results will help to identify valuable genetic resources that may be useful in future tea breeding programs.

Flavanols from the Camellia sinensis var.assamica and their hypoglycemic and hypolipidemic activities

α-Glucosidase and lipase inhibitors play important roles in the treatment of hyperglycaemia and dyslipidemia. To identify novel naturally occurring inhibitors, a bioactivity-guided phytochemical research was performed on the pu-erh tea. One new flavanol, named(–)-epicatechin-3-O-(Z)-coumarate(1), and 16 known analogs(2–17) were isolated from the aqueous extract of the pu-erh tea. Their structures were determined by spectroscopic and chemical methods. Furthermore, the water extract of pu-erh tea and its fractions exhibited inhibitory activities against α-glucosidases and lipases in vitro;compound 15 showed moderate inhibitory effect against sucrase with an IC_(50) value of 32.5 μmol/L and significant inhibitory effect against maltase with an IC_(50) value of 1.3 μmol/L. Compounds 8, 10, 11 and15 displayed moderate activity against a lipase with IC_(50) values of 16.0, 13.6, 19.8, and 13.3 μmol/L,respectively.

海南大叶茶野生种质表型性状多样性及相关分析

为海南大叶茶(Camellia sinensis var.assamica)野生资源的有效保护、优异种质挖掘及创新利用提供理论依据,本研究以五指山81份海南大叶茶野生茶树种质为研究对象,探究五指山海南大叶茶野生种质的形态特征和遗传多样性,明确海南大叶茶野生种质进化程度。结果表明,13个质量性状的多样性指数最大值为1.05,最小值为0.16;5个数量性状的变异系数范围在16.16%~37.21%之间,表现出丰富的遗传变异。性状相关性分析结果显示,7对呈显著正相关,10对呈极显著正相关,8对呈显著负相关,4对呈极显著负相关。对16个叶片表型性状进行主成分分析,提取出6个主成分,其累计贡献率73.196%。综合得分筛选出了8份叶片综合得分高的种质资源。聚类分析结果显示,在欧式距离为22处,可将供试的81株海南大叶茶野生茶树种质分为3类。