Biochemical component analysis and specific resource selection of 66 accessions of tea germplasms in Yunnan

【Objective】The genetic diversity of catechins and purine alkaloids of tea germplasms in Yunnan were identified. Afterwards, the specific tea genetic resources with high catechin index(CI) values and high theacrine content were screened according to the results, which provide scientific bases for tea breeding and product development.【Method】The predominant components of 66 representative tea germplasms in Yunnan, including catechins(+) -gallocatechin(GC), (-) -epigallocatechin(EGC), (+) -catechin(C), (-) -epicatechin(EC), (-) -epigallocatechin-3-gallate(EGCG), (-) -gallocatechin-3-gallate(GCG), (-) -epicatechin-3-gallate(ECG), purine alkaloids(caffeine, theobromine, and theacrine), were detected by high efficiency liquid chromatography(HPLC). Their genetic diversity(Shannon's diversity index, H') were performed by statistical software, principal component and cluster analysis were conducted. And the resources with high CI value and high theacrine were selected from the 66 accessions of tea germplasms.【Result】There were abundant genetic diversity and variability of GC, EGC, C, EC, EGCG, GCG, ECG, caffeine, theobromine in 66 Yunnan tea germplasms. Among them, the genetic diversity index of EGCG was the highest(2.06). Furthermore, the other components were greater than 1.8 except for EC and ECG. C had the largest coefficient of variation(66.07%), while theobromine had the smallest coefficient of variation(15.68%). Principal component analysis revealed that the cumulative contribution rate of the first five principal components presented the most of trait information as it reached 83.37%. Based on 14 biochemical components, 66 accessions of tea germplasms could be divided into four groups. And each groups had different main indicators such as CI value, theobromine, caffeine, and total catechins. A total of 13 tea germplasms with CI value greater than 0.60 were screened according to comprehensive analysis results, of which four were greater than 0.90(including two were more than 1.00);in addition, four tea germplasms with high theacrine(including three resources with low caffeine) were also identified.【Conclusion】Tea germplasms in Yunnan contain large variability of catechins and purine alkaloids, large variation coefficient. Therefore, they possess abundant genetic diversity. More importantly, 17 specific tea resources such as with high CI values, high theacrine, and low caffeine are selected.