Huang Rong, Wang Jun-Ya, Yao Ming-Zhe, Ma Chun-Lei, Chen Liang
Key Laboratory of Tea Biology and Resources Utilization, Ministry of Agriculture and Rural Affairs, Tea Research Institute of the Chinese Academy of Agricultural Sciences, Hangzhou 310008, China.
Hortic Res. 2022 Jan 5;9. doi: 10.1093/hr/uhab029.
Free amino acids are one of the main chemical components in tea, and they contribute to the pleasant flavor, function, and quality of tea, notably the level of theanine. Here, a high-density genetic map was constructed to characterize quantitative trait loci (QTLs) for free amino acid content. A total of 2688 polymorphic SNP markers were obtained using genotyping-by-sequencing (GBS) based on 198 individuals derived from a pseudotestcross population of "Longjing 43" × "Baijiguan", which are elite and albino tea cultivars, respectively. The 1846.32 cM high-density map with an average interval of 0.69 cM was successfully divided into 15 linkage groups (LGs) ranging from 93.41 cM to 171.28 cM. Furthermore, a total of 4 QTLs related to free amino acid content (theanine, glutamate, glutamine, aspartic acid and arginine) identified over two years were mapped to LG03, LG06, LG11 and LG14. The phenotypic variation explained by these QTLs ranged from 11.8% to 23.7%, with an LOD score from 3.56 to 7.7. Furthermore, several important amino acid metabolic pathways were enriched based on the upregulated differentially expressed genes (DEGs) among the offspring. These results will be essential for fine mapping genes involved in amino acid pathways and diversity, thereby providing a promising avenue for the genetic improvement of tea plants.
游离氨基酸是茶叶中的主要化学成分之一，它们对茶叶的宜人风味、功能和品质有重要贡献，尤其是茶氨酸的含量。在此，构建了一张高密度遗传图谱以鉴定游离氨基酸含量的数量性状位点（QTL）。基于“龙井43”ד白鸡冠”这一假测交群体的198个个体，通过简化基因组测序（GBS）共获得了2688个多态性SNP标记，这两个品种分别是优良和白化茶树品种。成功构建了一张长度为1846.32 cM的高密度图谱，平均间隔为0.69 cM，该图谱被成功划分为15个连锁群（LG），长度从93.41 cM到171.28 cM不等。此外，在两年时间内鉴定出的与游离氨基酸含量（茶氨酸、谷氨酸、谷氨酰胺、天冬氨酸和精氨酸）相关的4个QTL被定位到LG03、LG06、LG11和LG14上。这些QTL解释的表型变异范围为11.8%至23.7%，LOD值为3.56至7.7。此外，基于后代中上调的差异表达基因（DEG），富集了几个重要的氨基酸代谢途径。这些结果对于精细定位参与氨基酸途径和多样性的基因至关重要，从而为茶树的遗传改良提供了一条有前景的途径。
