The quality of tea is highly related with the maturity of the fresh tea leaves at harvest. The present study investigated the proteomic and transcriptomic profiles of tea leaves with different maturity, using iTRAQ and RNA-seq technologies. A total of 4455 proteins and 27 930 unigenes were identified, with functional enrichment analyses of GO categorization and KEGG annotation. The compositions of flavonoids (catechins and flavonols) in tea leaves were determined. The total content of flavonoids decreased with leaf maturity, in accordance with the protein regulation patterns of shikimate, phenylpropanoid, and flavonoid pathways. The abundance of ANR had a positive correlation with epi-catechin content, while LAR abundance was positively related with catechin content (P < 0.05). The biosynthetic network of flavonoid biosynthesis was discussed in combination with photosynthesis, primary metabolism, and transcription factors. Bud had the lowest activities of photosynthesis and carbon fixation but the highest flavonoid biosynthesis ability in opposite to mature leaf. SUS-INV switch might be an important joint for carbon flow shifting into the follow-up biochemical syntheses. This work provided a comprehensive overview on the functional protein profile changes of tea leaves at different growing stages and also proposed a research direction regarding the correlations between primary metabolism and flavonoid biosynthesis.

中文翻译：

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不同成熟度和黄酮类生物合成调控网络的茶树叶片iTRAQ蛋白质组和转录组分析的互补分析

茶的质量与收获时新鲜茶叶的成熟度高度相关。本研究使用iTRAQ和RNA-seq技术研究了不同成熟度的茶叶的蛋白质组学和转录组学特征。总共鉴定出4455种蛋白质和27 930个单基因，并对GO分类和KEGG注释进行了功能富集分析。测定茶叶中的类黄酮（儿茶素和黄酮醇）的组成。黄酮类化合物的总含量随叶片成熟而降低，这与sh草酸，苯丙烷和类黄酮途径的蛋白质调节模式一致。ANR的丰度与表儿茶素含量呈正相关，而LAR​​的丰度与儿茶素含量呈正相关（P<0.05）。结合光合作用，初级代谢和转录因子，讨论了类黄酮生物合成的生物合成网络。与成熟叶片相反，芽的光合作用和碳固定活性最低，但黄酮类生物合成能力最高。SUS-INV开关可能是碳流转移到后续生化合成过程中的重要环节。这项工作提供了对茶叶在不同生长阶段的功能性蛋白质谱变化的全面概述，并就初级代谢与类黄酮生物合成之间的相关性提出了研究方向。