Protective role of Mortierella alpina-derived lipids in resisting root rot in Panax ginseng

Root rot caused by Fusarium oxysporum is a major threat to the yield and quality of Panax ginseng. The use of antimicrobial compounds from antagonistic microorganisms is effective in controlling pathogens. Lipids from Mortierella can promote plant growth, but their role in disease resistance is unclear. In this study, we conducted a comprehensive analysis of the lipid components of Mortierella alpina and investigated the disease resistance properties and mechanisms of the total lipids and main component arachidonic acid (ARA). The results demonstrated that total lipids and arachidonic acid (ARA) directly inhibited the growth of F. oxysporum, F. solani, and Aspergillus sp., while promoting beneficial microorganisms such as Pseudomonas geniculate, Bacillus velezensis, and Trichoderma velutinum. These compounds also significantly induced the defense response of ginseng adventitious roots. Pot experiments revealed that total lipids and ARA significantly improved theresistance of ginseng to F. oxysporum root rot. Compared with F. oxysporum treatment alone, lipid addition increased the chlorophyll content, root length, fresh weight, and total saponin content. The increased expression of genes related to the jasmonic acid signaling pathway and relatively high nitrogen levels in the rhizosphere soil indicated increased defense mechanisms. Additionally, lipid addition increased the abundances of beneficial microorganisms such as Lysobacter, Gemmatimonas, Pedobacter, Pseudolabrys, and Mortierella, while decreasing Fusarium abundance. Overall, these findings demonstrate that Mortierella-derived lipids enhance ginseng resistance to root rot by directly inhibiting pathogens, modulating defense signaling pathways, and improving the rhizosphere microenvironment.