Screen and Genetic Assessment of Tea Germplasms with Elevated Methylated Catechin, (-)-Epigallocatechin-3-O-(3-O-methyl)gallate

摘要

The aim of this research was to identify tea varieties containing high levels of catechin methyl ester that could be used as important sources for genetic breeding and in the production of high quality tea. We examined 113 species that have been preserved in the Taitung Branch of the Tea Research and Extension Station of Taiwan (TTES). The average level of (-)-epigallocatechin-3-O-(3-O-methyl) gallate (EGCG3"Me) was 0.45% for all varieties screened. Among them, 16 varieties with higher EGCG3"Me.content (>0.8%) were considered good candidates for manufacturing partially fermented tea. Analysis of these tea varieties revealed that the EGCG3"Me content in leaves did not correlate with the caffeine content. Genetic assessments revealed that the lengths of their internal transcribed spacers (ITS) were in the range of 638-670 bp and that the sequence identities were in the range of 0.690-1. Two major groups were constructed by phylogenetic analysis, I and II, with a genetic distance of 0.08 based on the ITS1-5.8S-ITS2 sequences between the ribosomal genes. Our results provide genetic information about tea varieties with elevated EGCG3"Me content and indicate the need for a comprehensive genetic assessment of tea germplasms preserved in the TTES to better serve the future of tea breeding.