Quantitative Trait Loci Mapping for Theobromine and Caffeine Contents in Tea Plant (Camellia sinensis)

Understanding the genetic basis of
theobromine and caffeine accumulation
in the tea plant is important due to their contribution to tea flavor.
Quantitative trait loci (QTL) analyses were carried out to identify
genetic variants associated with theobromine and caffeine contents
and ratio using a pseudo-testcross population derived from an intervarietal
cross between two varieties of Camellia sinensis.
A total of 10 QTL controlling caffeine content (CAF), theobromine
content (TBR), sum of caffeine and theobromine (SCT), and caffeine-to-theobromine
ratio (CTR) were identified over four measurement years. The major
QTL controlling CAF, qCAF1, was mapped onto LG01
and validated across years, explaining an average of 20.1% of the
phenotypic variance. The other QTL were detected in 1 or 2 years,
and of them there were four, two, and three for TBR, SCT, and CTR,
respectively. The present results provide valuable information for
further fine mapping and cloning functional genes and for genetic
improvement in tea plant.

洞悉茶树中可可碱与咖啡碱积累的遗传基础具有重要意义，因其对茶风味贡献显著。通过利用由两个品种的茶树（Camellia sinensis）杂交产生的伪测交群体，进行数量性状位点（QTL）分析，旨在识别与可可碱和咖啡碱含量及其比例相关的遗传变异。在四个测量年度内，共鉴定出10个控制咖啡碱含量（CAF）、可可碱含量（TBR）、咖啡碱与可可碱总和（SCT）以及咖啡碱与可可碱比（CTR）的QTL。其中，主导CAF的QTL，即qCAF1，被定位在LG01上，并在多年间得到验证，平均解释了20.1%的表型变异。其他QTL则在1至2年内被检测到，其中TBR、SCT和CTR分别有4、2和3个。本研究结果为后续精细定位和克隆功能基因，以及茶树遗传改良提供了宝贵信息。