Black net shade treatment attenuates flavonoid biosynthesis in tea plants, while the effect of light quality is still unclear. We investigated the flavonoid and transcriptome profiles of tea leaves under different light conditions, using black nets with different shade percentages, blue, yellow and red nets to alter the light intensity and light spectral composition in the fields. Flavonol glycosides are more sensitive to light intensity than catechins, with a reduction percentage of total flavonol glycosides up to 79.6% compared with 38.7% of total catechins under shade treatment. A total of 29,292 unigenes were identified, and the KEGG result indicated that flavonoid biosynthesis was regulated by both light intensity and light spectral composition while phytohormone signal transduction was modulated under blue net shade treatment. PAL, CHS, and F3H were transcriptionally downregulated with light intensity. Co-expression analysis showed the expressions of key transcription factors MYB12, MYB86, C1, MYB4, KTN80.4, and light signal perception and signaling genes (UVR8, HY5) had correlations with the contents of certain flavonoids (p < 0.05). The level of abscisic acid in tea leaves was elevated under shade treatment, with a negative correlation with TFG content (p < 0.05). This work provides a potential route of changing light intensity and spectral composition in the field to alter the compositions of flavor substances in tea leaves and regulate plant growth, which is instructive to the production of summer/autumn tea and matcha.

中文翻译：

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光强和光谱成分对遮荫茶树（Camellia sinensis L.）叶片转录组谱和类黄酮生物合成调控网络的影响

黑网遮荫处理减弱了茶树中黄酮类化合物的生物合成，而光质的影响尚不清楚。我们研究了不同光照条件下茶叶的黄酮类化合物和转录组谱，使用具有不同阴影百分比的黑网、蓝色、黄色和红色网来改变田间的光强度和光谱组成。黄酮醇苷对光强度比儿茶素更敏感，总黄酮醇苷的减少百分比高达 79.6%，而遮荫处理下的总儿茶素减少百分比为 38.7%。共鉴定出29,292个unigenes，KEGG结果表明黄酮类生物合成受光强度和光谱组成的调节，而植物激素信号转导在蓝网遮荫处理下受到调节。PAL、CHS和F3H在光强度下被转录下调。共表达分析表明，关键转录因子MYB12、MYB86、C1、MYB4、KTN80.4以及光信号感知和信号基因（UVR8、HY5）的表达与某些黄酮类化合物的含量存在相关性（p <0.05）。遮荫处理茶叶脱落酸水平升高，与TFG含量呈负相关（p< 0.05)。该工作提供了一种在田间改变光强和光谱组成以改变茶叶中风味物质组成并调节植物生长的潜在途径，对夏/秋茶和抹茶的生产具有指导意义。