Chinese scientists have made important breakthroughs in the study of the whole genome assembly and the origin and evolution of tea trees.The research was conducted by the Tea Research Institute of the Chinese Academy of Agricultural Sciences and the Shenzhen Institute of Agricultural Genomics of the Chinese Academy of Agricultural Sciences.The results provided abundant materials for the genomics and breeding research of tea tree, as well as the research on the inheritance and evolution of tea tree.

Tea originated from China and became popular in the world, and the world tea drink consumption population has exceeded two thirds.Tea tree is widely distributed in China with abundant germplasm resources, and the six types of tea have their own characteristics. However, there are few studies on the evolution of tea tree.

First of all, with the famous tea plant variety Longjing 43 as the material, the third-generation assembly software independently developed by them combined with high-throughput chromosomal conformation capture and other technologies overcame the complex genome assembly problems with high hybrid genome and high repeat sequence ratio, and completed the genome assembly at the level of Longjing 43.

Longjing 43 had a genome size of 3.26 Gb and A DNA framework of N50 of 143.85 Mb with good continuity. Both the single base level and scaffold level achieved high accuracy, and 33556 high quality annotated genes were obtained.

The results showed that longjing 43 was associated with disease resistance, flavor metabolism and self-incompatibility gene family expansion and positive selection of genes related to stress resistance.

Based on the assembled high-quality genome, the team conducted a deep resequencing of 139 representative tea tree materials from different countries and regions of the world, revealing the systematic relationships of tea population and mapping the evolutionary history of cultivated tea trees.

They found that the expansion of cultivated areas increased heterozygosity and extensive gene flow among tea populations;The wild relative population of tea tree is the ancestor of medium and large leaf tea species, and the selection direction of them is different during domestication.Terpene metabolism genes and disease resistance genes related to tea flavor were selected to be stronger than those of macrophylla tea during long-term domestication.

Longjing 43 is an excellent variety originated from Longjing population of West Lake. It is welcomed by Chinese tea farmers for its excellent economic characters such as early germination, excellent quality and strong resistance to stress, etc. It is in the forefront of the promotion area in the main producing areas of green tea in China.This year marks the 60th anniversary of the discovery of Longjing 43. The results of this study explain the molecular nature of the excellent and resilient Quality of Longjing 43, which is of great commemorative significance.

Time: 2020.09.10

Source: http://www.caas.cn/xwzx/mtbd/307557.html