Lin Xinying, Shao Shuxian, Wang Pengjie, Yang Ruxing, Zheng Yucheng, Chen Xiaomin, Zhang Lei, Ye Naixing
Key Laboratory of Tea Science at Universities in Fujian, College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, Fujian, China.
Agriculture Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, Guangdong, China.
Sheng Wu Gong Cheng Xue Bao. 2022 Oct 25;38(10):3956-3972. doi: 10.13345/j.cjb.220071.
To explore the mechanism of tea albino variation and high theanine formation, 'Fuyun 6' and a new theanine-rich tea cultivar 'Fuhuang 2' were as materials in this study, pigment content, metabolome and transcriptome of the two cultivars were analyzed by ultramicroelectron microscopy, widely targeted metabolomics, targeted metabolomics and transcriptomics. The results showed that five catechins, theobromine, caffeine, and 20 free amino acids, including theanine, glutamine, arginine, etc., were identified by targeted metabolomics. The amino acid content of 'Fuhuang 2' was significantly higher than that of 'Fuyun 6', and the theanine content was as high as 57.37 mg/g in 'Fuhuang 2'. The ultrastructure of leaves showed that the chloroplast cell structure of 'Fuhuang 2' was fuzzy, most of the grana lamellae were arranged in disorder, with large gaps, and the thylakoids were filiform. The determination of pigments showed that compared with 'Fuyun 6', the contents of chlorophyll A and B, carotenoids, flavonoids and other pigments of 'Fuhuang 2' decreased significantly, some important pigment-related-genes, such as chlorophyllase (), 9--epoxycarotenoid dioxygenase (), flavonoid 3β-hydroxylase () and flavonoid 3', 5'-hydroxylase () were significantly changed. Compared with 'Fuyun 6', 'Fuhuang 2' identified 138 significantly changed metabolites (SCMs) and 658 differentially expressed genes (DEGs). KEGG enrichment analysis showed that SCMs and DEGs were significantly enriched in amino acid biosynthesis, glutathione metabolism and TCA cycle. In general, the albino phenotype of 'Fuhuang 2' may be caused by a deficiency in photosynthetic proteins, chlorophyll metabolism genes and chlorophyll content. The accumulation of high theanine in 'Fuhuang 2' may be due to the low nitrogen consumption in yellowed leaves and the lack of carbon skeleton, amino and nitrogen resources are stored more effectively, resulting in the up regulation of metabolites and related gene expression in the amino acid synthesis pathway, theanine has become a significant accumulation of nitrogen-containing compounds in yellowed leaves.
为探究茶树白化变异及高茶氨酸形成的机制，本研究以‘福云6号’和一个新的富含茶氨酸的茶树品种‘福黄2号’为材料，通过超微电子显微镜、广泛靶向代谢组学、靶向代谢组学和转录组学分析了两个品种的色素含量、代谢组和转录组。结果表明，通过靶向代谢组学鉴定出了5种儿茶素、可可碱、咖啡因以及20种游离氨基酸，包括茶氨酸、谷氨酰胺、精氨酸等。‘福黄2号’的氨基酸含量显著高于‘福云6号’，其茶氨酸含量高达57.37mg/g。叶片超微结构显示，‘福黄2号’的叶绿体细胞结构模糊，多数基粒片层排列紊乱，间隙较大，类囊体呈丝状。色素测定表明，与‘福云6号’相比，‘福黄2号’的叶绿素A、叶绿素B、类胡萝卜素、黄酮类等色素含量显著降低，一些重要的色素相关基因，如叶绿素酶（）、9-顺式环氧类胡萝卜素双加氧酶（）、黄酮3β-羟化酶（）和黄酮3′,5′-羟化酶（）发生了显著变化。与‘福云6号’相比，‘福黄2号’鉴定出138个显著变化的代谢物（SCMs）和658个差异表达基因（DEGs）。KEGG富集分析表明，SCMs和DEGs在氨基酸生物合成、谷胱甘肽代谢和三羧酸循环中显著富集。总体而言，‘福黄2号’的白化表型可能是由光合蛋白、叶绿素代谢基因和叶绿素含量不足引起的。‘福黄2号’中高茶氨酸的积累可能是由于黄叶中氮消耗较低且缺乏碳骨架，氨基酸和氮资源更有效地储存，导致氨基酸合成途径中代谢物和相关基因表达上调，茶氨酸成为黄叶中含氮化合物的显著积累物。
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