Profiling lipid changes in Panax notoginseng upon Alternaria panax infection

Abstract

The growth of Panax notoginseng is stressed by various biotic and abiotic factors. Alternaria panax Whetzel is a destructive pathogen causing black spot disease of P. notoginseng, thereby severely reducing the yield and quality of P. notoginseng. However, it is still unknown in lipids change of P. notoginseng after A. panax infection. In this study, we compared the lipidomics data of normal and infected P. notoginseng to evaluate the effects of A. panax stress on lipids, and a total of 1202 lipid molecules were identified. All lipid molecules involved 34 subclasses, among which 12 subclasses were significantly up-regulated after pathogen stress. WGCNA co-expression network analysis revealed four significantly related lipid modules, including 459 lipid molecules. Differential expression analysis of all lipid molecules showed that 196 lipid molecules were significantly up-regulated and 78 lipid molecules were significantly down-regulated. The up-regulated lipid molecules were mainly Cer subclasses, while the down-regulated lipid subclasses were mainly DG, MG, PA, SQDG and SQMG. Autocorrelation analysis of differentially expressed lipid molecules showed that lipid networks in response to pathogen stress were mainly composed of lipid molecules in TG, Cer, SQDG and DGDG. Meanwhile, the lipid synthesis pathway found that 17 lipid subclasses had mutual regulatory relationships, 10 subclasses were significantly up-regulated after pathogen stress. All the results showed that these significantly different lipid molecules were involved in pathogen stress response. This study provides new reference for the search of antifungal candidate biomarkers and defense response metabolites based on lipids.