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.
J Agric Food Chem. 2020 Jul 29;68(30):8068-8079. doi: 10.1021/acs.jafc.0c01883. Epub 2020 Jul 20.
The young leaves and shoots of albino tea cultivars are usually characterized as having a yellow or pale color, high amino acid, and low catechin. Increasing attention has been paid to albino tea cultivars in recent years because their tea generally shows high umami and reduced astringency. However, the genetic mechanism of yellow-leaf variation in albino tea cultivar has not been elucidated clearly. In this study, bulked segregant RNA-seq (BSR-seq) was performed on bulked yellow- and green-leaf hybrid progenies from a leaf color variation population. A total of 359 and 1134 differentially expressed genes (DEGs) were identified in the yellow and green hybrid bulked groups (Y vs G) and parent plants (Y vs G), respectively. The significantly smaller number of DEGs in Y versus G than in Y versus G indicated that individual differences could be reduced within the same hybrid progeny. Analysis of Gene Ontology and Kyoto Encyclopedia of Genes and Genomes revealed that the photosynthetic antenna protein was most significantly enriched in either the bulked groups or their parents. Interaction was found among light-harvesting chlorophyll / -binding proteins (LHC), heat shock proteins (HSPs), and enzymes involved in cuticle formation. Combined with the transcriptomic expression profile, results showed that the repressed genes encoding LHC were closely linked to aberrant chloroplast development in yellow-leaf tea plants. Furthermore, the photoprotection and light stress response possessed by genes involved in HSP protein interaction and cuticle formation were discussed. The expression profile of DEGs was verified via quantitative real-time PCR analysis of the bulked samples and other F individuals. In summary, using BSR-seq on a hybrid population eliminated certain disturbing effects of genetic background and individual discrepancy, thereby helping this study to intensively focus on the key genes controlling leaf color variation in yellow-leaf tea plants.
白化茶品种的嫩叶和嫩梢通常表现为黄色或浅黄色，具有高氨基酸和低儿茶素的特点。近年来，白化茶品种受到了越来越多的关注，因为它们的茶叶通常具有高鲜味和低涩味。然而，白化茶品种黄叶变异的遗传机制尚未得到明确阐明。在这项研究中，对来自叶色变异群体的黄色和绿色杂种后代进行了混池分离群体 RNA 测序（BSR-seq）。在黄色和绿色杂种混池群体（Y 与 G）和亲本植物（Y 与 G）中，分别鉴定到 359 个和 1134 个差异表达基因（DEGs）。Y 与 G 中的 DEGs 数量明显少于 Y 与 G，表明同一杂种后代内的个体差异可以减少。GO 和 KEGG 分析表明，在混池群体或其亲本中，光合作用天线蛋白的富集程度最高。发现在 LHC 与 HSP 之间存在相互作用，LHC 是光捕获叶绿素/结合蛋白，HSP 是热激蛋白，并且与角质层形成有关的酶也存在相互作用。结合转录组表达谱，结果表明，编码 LHC 的受抑制基因与黄叶茶树中异常叶绿体发育密切相关。此外，还讨论了 HSP 蛋白互作和角质层形成相关基因在光保护和光胁迫响应中的作用。通过对混池样本和其他 F1 个体的定量实时 PCR 分析验证了 DEGs 的表达谱。综上所述，在杂种群体中使用 BSR-seq 消除了遗传背景和个体差异的某些干扰效应，从而有助于本研究集中研究控制黄叶茶树叶片颜色变异的关键基因。
