Pea-Tea Intercropping Improves Tea Quality through Regulating Amino Acid Metabolism and Flavonoid Biosynthesis.

Pea-tea intercropping is an excellent cultivation method that can improve tea quality. However, the underlying mechanism is still unclear. The present study was aimed at elucidating the mechanism of the effect of pea-tea intercropping on tea quality through a high-throughput method. Transcriptome and metabolome analyses were conducted to identify the changes in gene expression and metabolites changes intercropping, respectively. In addition, the amino acids and catechins were detected using the LC-MS method and quantified absolutely. The results showed that total polyphenols and catechins decreased but amino acids increased in pea intercropped tea shoots. Correspondingly, genes related to amino acid metabolism and flavonoid biosynthesis were differentially expressed. For amino acid metabolism, 11 differentially expressed genes were identified, including 5 upregulated and 6 downregulated genes. Meanwhile, three genes involved in carbohydrate transport and metabolism were upregulated in pea intercropped tea plants. These genes were also involved in amino acid metabolism. For flavonoid biosynthesis, two downregulated genes were identified, which were the flavonol synthase and anthocyanidin synthase genes and followed a similar pattern to changes in catechins and polyphenols. These advances have opened new horizons for understanding the biochemical mechanisms of amino acids and flavonoids in improving tea quality in the pea-tea intercropping cultivation model.

Molecular Link in Flavonoid and Amino Acid Biosynthesis Contributes to the Flavor of Changqing Tea in Different Seasons.

The present study was aimed to elucidate the flavor formation mechanism of Changqing tea. High-performance liquid chromatography (HPLC) analysis showed that the total catechins of Changqing tea was 65-160 mg/g, with 16-34 mg/g non-galloyated catechins and 49-126 mg/g galloylated catechins. Tea polyphenols and free amino acids account for 286-312 mg/g and 35-89 mg/g, respectively. Transcriptome of Changqing tea during different seasons revealed 316, 130 and 12 DEGs in comparisons of spring vs. autumn, spring vs. summer, and summer vs. autumn, respectively. Compared to spring, the genes involved in flavonoid biosynthesis and bitter imparted amino acids were up-regulated in summer and autumn. Metabolome analysis was conducted by using HPLC-MS; the result indicated that umami and kokumi contributing amino acids were decreased in summer and autumn compared with spring. It could be concluded that the coordination of flavonoid biosynthesis and amino acids biosynthesis resulted in the special flavor of Changqing tea.

Red Light Regulates the Metabolite Biosynthesis in the Leaves of "Huangjinya" Through Amino Acid and Phenylpropanoid Metabolisms.

"Huangjinya" is a light-sensitive albino variety and is widely cultivated in China. It has been proved that red light could promote the vegetable growth of plants. However, the mechanism of "Huangjinya" in response to a red light is unclear. This study used high-throughput sequencing technology to analyze the transcriptome of tender shoots of "Huangjinya" under the white and red light supplement conditions. At the same time, liquid chromatography tandem mass spectrometry (LC-MS) was used to analyze metabolite changes under different light conditions. Transcriptome analysis revealed that a total of 174 differentially expressed genes (DEGs) were identified after the red light supplement. Kyoto encyclopedia of genes and genomes (KEGG) classification indicated that amino acid metabolism enriched the most DEGs. In addition, two phenylpropanoid metabolism-related genes and five glutathione S-transferase genes (CsGSTs) were found to be expressed differently. Metabolome analysis revealed that 193 differential metabolites were obtained. Being the same as transcriptome analysis, most differential metabolites were enriched in amino acids, sweet and umami tasting amino acids were increased, and bitter-tasting amino acids were decreased after the red light supplement. In summary, red light supplementary treatment may be propitious to the quality of "Huangjinya" due to its regulatory effect on amino acid metabolism. Also, CsGSTs involved phenylpropanoid metabolism contributed to tea quality changes in "Huangjinya."