Table1_Combined metabolome and transcriptome analyses reveal that growing under Red shade affects secondary metabolite content in Huangjinya green tea.XLSX

Shading treatments impact the tea (Camellia sinensis L.) quality. The sunlight sensitive varieties can be grown under shading nets for better growth and secondary metabolite content. Here, we studied the responses of a sunlight sensitive green tea variety “Huangjinya” by growing under colored shading nets (red, yellow, blue, and black (75% and 95%) shading rates) to find out the most suitable color of the shading net. Red shading was the most promising treatment as it positively affected the weight and length of 100 one-bud-three leaves and reduced the degree and rate of new shoots burn compared to control (natural sunlight). We then explored the comparative metabolomic changes in response to red shading by using UPLC-ESI-MS/MS system. The amino acids and derivatives, flavonoids, and alkaloids were downaccumulated whereas lipids, organic acids, and lignans were upaccumulated in Red shade grown tea samples. The red shading nets caused a decreased catechin, epicatechin, dopamine, and L-tyramine contents but increased caffeine content. We then employed transcriptome sequencing to find key changes in expressions of related genes and pathways. Notably, key genes associated with the phenylpropanoid and flavonoid biosynthesis pathways exhibited complex regulation. These expression changes suggested a potential trend of polymerization or condensation of simple molecules like catechin or pelargonidin into larger molecules like glucoside or proanthocyanidins. Here, Red shading net triggered higher expression of genes enriched in lipid biosynthesis and jasmonic acid biosynthesis, suggesting an interplay of fatty acids and JA in improving tea performance. These findings contribute to the metabolic responses of Huangjinya tea to red shading nets which might have implications for flavor and health benefits. Our data provide a foundation for further exploration and optimization of cultivation practices for this unique tea variety.

遮荫处理会影响茶树（Camellia sinensis L.）的品质。对光照敏感的茶树品种可通过遮荫网栽培，以获得更优良的生长状态与次生代谢产物积累水平。本研究以光照敏感型绿茶品种“黄金芽”为材料，设置红、黄、蓝、黑四种颜色的遮荫网（遮荫率分别为75%和95%）进行栽培，旨在筛选最适宜的遮荫网颜色。相较于对照组（自然光照），红色遮荫处理效果最优：其可显著提升100个一芽三叶的鲜重与叶长，并降低新梢灼伤程度与发生率。随后，本研究采用超高效液相色谱-电喷雾电离串联质谱（UPLC-ESI-MS/MS）系统，分析了红色遮荫处理下茶树的差异代谢组变化。红色遮荫栽培的茶树样本中，氨基酸及其衍生物、黄酮类化合物与生物碱的积累量呈下调趋势，而脂质、有机酸与木脂素的积累量则显著上调。红色遮荫处理可降低儿茶素、表儿茶素、多巴胺与L-酪胺的含量，同时提升咖啡因的积累水平。随后，本研究通过转录组测序技术，解析了相关基因与通路的表达调控关键变化。值得注意的是，与苯丙烷类及黄酮类生物合成通路相关的关键基因呈现出复杂的调控模式。上述表达变化表明，儿茶素、天竺葵素等简单分子存在聚合或缩合为糖苷、原花青素等大分子的潜在趋势。红色遮荫网可诱导脂质生物合成与茉莉酸（jasmonic acid, JA）生物合成相关基因的高表达，表明脂肪酸与茉莉酸之间存在互作，进而改善茶树生长表现。本研究结果揭示了“黄金芽”茶树对红色遮荫网的代谢响应机制，该结果可为优化茶叶风味与健康功效提供参考。本研究数据为该特色茶树品种的栽培模式进一步探索与优化提供了理论基础。