Discovery and identification of favourable haplotypes for metabolic traits in tea germplasm

在HAPLOTEA项目中，我们将分析茶叶中的代谢多样性，并结合代谢物含量和遗传分析。我们认为，缺乏任何可观察到的驯化瓶颈和高遗传多样性和杂合性在现存的茶树种质将反映在一个强大的代谢多样性在茶叶。这一假设与我们目前关于茶遗传学的数据一致，表明茶种质中的高度杂交，并且基于茶叶加工对茶饮料中风味的高度重要性，可能掩盖了对赋予风味的组分的许多遗传效应。我们将为200多个茶树品种建立深层代谢谱，并将其与表达和遗传多态性数据相结合。基于这些联合数据，我们将使用全基因组关联研究将代谢物含量与遗传区域联系起来，我们将为15个茶树品种的选择生成单倍型解析的基因组组装。这将允许观察单倍型差异，并将代谢物含量与特定的单倍型和-使用生化知识-潜在的候选基因联系起来。在我们以前的工作中，我们可以证明存在两种主要的等位基因形式的参与儿茶素代谢的酶，其在体外表达时显示出明显不同的催化特性。 因此，我们将分析多达10个候选基因在其不同等位基因形式中的酶差异，以研究这种催化酶差异是否在茶中常见并有助于代谢多样性。

Within the project HAPLOTEA we will analyze the metabolic diversity in tea and couple metabolite content and genetic analyses. We believe that the lack of any observable domestication bottleneck and the high genetic diversity and heterozygosity in extant tea germplasm will be reflected in a strong metabolic diversity in tea. This hypothesis is in line with our current data on tea genetics suggesting a high degree of hybridization in tea accessions and based on the high importance of tea leaf processing on flavor in the tea beverage likely masking many genetic effects on flavor bestowing components.To investigate this hypothesis, we will generate deep metabolic profiles for an established collection of more than 200 tea accessions and will couple this with expression and genetic polymorphism data. Based on these joint data, we will link metabolite content to genetic regions using genome wide association studies and we will generate haplotype resolved genome assemblies for a selection of 15 tea accessions. This will allow to observe haplotype divergence and to link metabolite content to specific haplotypes and -using biochemical knowledge- underlying candidate genes. In on our previous work we could show the existence of two major allelic versions of an enzyme involved in catechin metabolism which showed markedly different catalytic properties when expressed in vitro. Hence, we will analyze up to 10 candidate genes for enzymatic differences in their different allelic forms to investigate if such catalytic enzyme differences are common in tea and are contributing to metabolic diversity.