# Effect of Mechanical Damage in Green-Making Process on Aroma of Rougui Tea
## 3 Results
### Analysis of DEGs and DEPs Related to Biosynthesis of Aroma Components
Under long-term mechanical injury and dehydration, the alcohol expression of the key enzyme genes in the terpenenoid skeleton synthesis pathway maintained the trend of upregulation during the green-making and spreading process, and the expression level of cytoplasmic MVA pathway-related genes was more obvious than that of the plastid MEP pathway in the green-making process. In the monoterpene and sesquiterpene biosynthetic pathway, the expression intensity of the sesquiterpene synthetase gene was higher than that of the monoterpene synthetase gene in the green-making process, and the expression intensity of the sesquiterpene synthase gene reached the highest level at the end of the fifth shaking step. Most of the monoterpene synthase genes reached the highest levels at the end of the first shaking  
Figure 5: DEGs and DEPs involved in \(\alpha\)-linolenic acid metabolism, terpenoid biosynthesis and phenylalanine metabolism pathway. (**A**) \(\alpha\)-linolenic acid metabolism pathway; (**B**) terpenoid biosynthesis pathway; (**C**) phenylalanine metabolism pathway.Dashed boxes represent downstream metabolites and dashed circle represents upstream metabolic pathway. step and then decreased. Most of the genes involved in sesquiterpene synthesis were upregulated after tea picking, while most of the genes involved in monoterpene synthesis were downregulated [50]. Our results are similar to those of previous studies. Studies have shown that multiple mechanical injuries during the processing of RGT can promote an increase in neroli tertiary alcohol synthase gene expression and the accumulation of a large amount of neroli tertiary alcohols, and the synergistic effect of low temperatures and mechanical injury is more conducive to the accumulation of neroli tertiary alcohols [51]. In conclusion, the green-making process of RGT was more conducive to the expression of sesquiterpene aroma synthesis-related genes, while the CK group promoted the expression of monoterpene aroma synthesis-related genes. At the same time, the data on the content of volatile compounds showed that the content of linalool in the LY group was lower than that in the CK group, while the content of nerolidol was higher than that in the CK group, which was consistent with the gene expression patterns. Phenylalanine is a precursor of tea aromatic compounds, and its metabolic pathway is regulated by several genes. The differential genes that are enriched in the metabolic pathway are mainly related to the synthesis of phenylpyruvate. Phenylalanine is induced by aspartate aminotransferase (ASP) and tyrosine aminotransferase (TAT) to form phenylpyruvate, which is catalyzed to generate phenylacetaldehyde, phenylethyl alcohol and so on [52]. In addition, phenethylamineamine can also produce phenylacetaldehyde under the catalysis of primary amine oxidase (tynA) (TEA029368.1). After sun withering, the ASP gene expression gradually increased under the effects of continuous mechanical injury and dehydration, and it reached the highest level at the end of green-making and spreading. The green-making process had a more obvious effect on the upregulation of the gene, and a coding protein (TEA024318.1) with a similar expression pattern was detected. In addition, a bifunctional aspartate aminotransferase and glutamate (PAT) gene and related proteins were significantly upregulated during the green-making process (\(p<0.05\)), and the tynA gene (TEA029368.1) also showed a similar trend (Figure 5C). The green-making process promoted the synthesis of phenylpyruvate, which increased the aroma volatiles, compared to the spreading process. The content of phenylacetaldehyde and phenylethyl alcohol in the LY group in ZM and DM was higher than that in the CK group. Five phenylalanine aminoylase genes (PAL) can catalyze phenylalanine to form trans-cinamic acid, which gradually forms benzene ring compounds through other pathways and finally forms benzyl alcohol, benzoic acid and other aromatic compounds [30].