College of Horticulture, South China Agricultural University, Guangzhou 510642, China.
Center for Basic Experiments and Practical Training, South China Agricultural University, Guangzhou 510642, China.
Int J Mol Sci. 2022 Nov 30;23(23):15044. doi: 10.3390/ijms232315044.
Leaf color is one of the key factors involved in determining the processing suitability of tea. It relates to differential accumulation of flavor compounds due to the different metabolic mechanisms. In recent years, photosensitive etiolation or albefaction is an interesting direction in tea research field. However, the molecular mechanism of color formation remains unclear since albino or etiolated mutants have different genetic backgrounds. In this study, wide-target metabolomic and transcriptomic analyses were used to reveal the biological mechanism of leaf etiolation for 'Huangyu', a bud mutant of 'Yinghong 9'. The results indicated that the reduction in the content of chlorophyll and the ratio of chlorophyll to carotenoids might be the biochemical reasons for the etiolation of 'Huangyu' tea leaves, while the content of zeaxanthin was significantly higher. The differentially expressed genes (DEGs) involved in chlorophyll and chloroplast biogenesis were the biomolecular reasons for the formation of green or yellow color in tea leaves. In addition, our results also revealed that the changes of DEGs involved in light-induced proteins and circadian rhythm promoted the adaptation of etiolated tea leaves to light stress. Variant colors of tea leaves indicated different directions in metabolic flux and accumulation of flavor compounds.
叶片颜色是决定茶叶加工适制性的关键因素之一。它与风味化合物的差异积累有关，这是由于不同的代谢机制造成的。近年来，光敏感黄化或白化是茶叶研究领域的一个有趣方向。然而，由于白化体或黄化突变体具有不同的遗传背景，因此颜色形成的分子机制仍不清楚。在这项研究中，我们使用广泛靶向代谢组学和转录组学分析来揭示‘黄玉’（‘迎红 9 号’的芽变品种）叶片黄化的生物学机制。结果表明，叶绿素含量和叶绿素与类胡萝卜素比值的降低可能是‘黄玉’茶树叶黄化的生化原因，而玉米黄质的含量则显著升高。参与叶绿素和叶绿体生物发生的差异表达基因（DEGs）是茶叶形成绿色或黄色的生物分子原因。此外，我们的研究结果还表明，光诱导蛋白和昼夜节律相关的 DEGs 的变化促进了黄化茶树叶对光胁迫的适应。叶片的变异颜色表明代谢通量和风味化合物积累的方向不同。
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