Integration analysis of transcriptomics and proteomics reveals the inhibitory effect of carvacrol on Alternaria alternata by interfering with carbohydrate metabolism

The cell wall of pathogenic fungi is critical for maintaining cell integrity and promoting host infection. Our previous study found that carvacrol (CVR) can inhibit the growth of Alternaria alternata by interfering with the accumulation of cell wall polysaccharides. To gain a deeper understanding of how CVR affects saccharide accumulation in A. alternata, this study analyzed changes in the carbohydrate content of the fungi. The results showed that CVR reduced the cell wall thickness, chitin and β-1,3-glucan distribution, glycogen accumulation, and the total sugar, trehalose, mannose, fructose, and galactose contents in A. alternata. Further transcriptomic and proteomic analyses revealed that CVR treatment accelerated the decomposition of cell wall polysaccharides in the fungi, hindered sucrose consumption, disrupted the glycolysis pathway, and promoted the decomposition of carbohydrates related to stress resistance. Meanwhile, the results of quantitative real-time PCR were consistent with the above findings. In addition, the results of the carbon source culture showed that CVR treatment improved the utilization ability of A. alternata in cellulose and starch while inhibiting the utilization of pectin and sucrose. These results indicate that CVR affects carbohydrate metabolism, which is associated with A. alternata growth, infection, and stress resistance of A. alternata.