# 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
The PAL gene expression was mostly upregulated during green-making and spreading, but the expression trends of the three coding proteins were inconsistent with the transcripts. The content of benzyl alcohol and benzaldehyde in the LY group in ZM and DM was higher than that in the CK group. In addition, the expression levels of two tryptophan synthase (TSB) genes related to indole biosynthesis showed an increasing trend in the LY and CK groups, and the corresponding protein expression trend was consistent, but there was no significant difference between LY7 and CK7. During the processing of RGT, the TSB gene can be induced and upregulated, and some studies have shown that the indole content of its product can be increased only under the contrasting effects of the TSA and TSB genes [53], but no TSA gene was detected in this experiment. The volatile compound data showed that, in addition to the large enrichment of nerolidol and indole, the aliphatic alcohols, esters, jasmone and jasmine lactone in the LY group were also significantly increased compared with the CK group (\(p<0.05\)). Previous studies have shown that the fruity flavor of RGT is mainly based on six ester substances, such as (Z)-3-hexen-1-yl butyrate, (E)-3-hexen-1-yl butyrate, 5-hexenyl butyrate and so on. Due to abiotic stresses such as high temperatures and mechanical injury, the expression of structural genes in the LOX pathway of unsaturated fatty acids can be induced during the manufacturing process, thereby enhancing the activity of key enzymes and promoting the oxidative degradation of unsaturated fatty acids (linoleic acid and \(\alpha\)-linolenic acid), further forming rich fatty aroma compounds and jasmonic acid compounds [54]. The degradation of fatty acids in RGT manufacturing and processing is conducive to the formation of fatty acid-derived volatiles (FADV) and produces cyclic aroma compounds such as methyl jasmonate, jasmonone and jasmonolide [55]. According to the transcriptome and proteome data, the expression of \(\alpha\)-linolenic acid metabolism pathway-related genes was greater, and the expression abundance of differential proteins was higher. The fatty acid metabolic pathway is a key upstream metabolic process in the formation of FADV. The correlation analysis of the DEGs and DEPs in these two metabolic pathways further explained the metabolic patterns that promote the formation of the RGT aroma. The DEGs and DEPs related to fatty acid degradation, the biosynthesis of unsaturated fatty acids and \(\alpha\)-linolenic acid metabolism were analyzed (Figure 6A), which showed that the expression levels of the PED1, LACS7, MFP, TESB and ACAA genes were significantly and positively correlated with most differential proteins, while the expression levels of the LACS3, LOX3.1, OPCL, FAD7 and JMT genes were significantly and negatively correlated with most differential proteins (\(p<0.05\)). Differential proteins AOS, CAC3, fabD, ACX4, OPCL, LACS3 and OPR3 were closely related to most of the differential genes. The effect of fatty acid metabolism on the upstream metabolic precursors of volatile substances during the manufacturing process needs further study to explore the mechanism behind the floral and fruity aroma formation of RGT. During the green-making process of colony tea, the fatty acid content decreased gradually, while the fatty acid-derived volatiles increased, and the fatty acid ester content reached the highest level at the fourth shaking step [55]. Appropriately increasing the number of turns in the green-making process can improve the synthesis of aroma esters and promote the formation of fruity aromas.