Transcriptome reveals the toxicity difference of dimethyl disulfide by contact and fumigation on Meloidogyne incognita through calcium channel-mediated oxidative phosphorylation.

The prevention and control of root-knot nematode disease has been posing a severe challenge worldwide. Fumigant dimethyl disulfide (DMDS) has excellent biological activity against nematodes. However, DMDS displays significant differences in contact and fumigation toxicity on nematodes. The specific regulatory mechanisms of DMDS on nematodes were investigated by characterizing the ultrastructure of nematodes, examining the physiological and biochemical indicators, and conducting transcriptome high-throughput sequencing. As indicated by the results, DMDS fumigation exhibited the biological activity of against M. incognita 121 times higher than DMDS contact. DMDS contact destroyed nematode body wall cells. Besides, DMDS fumigation destroyed the structure of pseudocoelom. DMDS treatment expedited the oxygen consumption of nematode while inhibiting acetylcholinesterase activity. As indicated by the analysis of vital signaling pathways based on transcriptome, DMDS based on the contact mode penetrated directly into the nematode through the body wall and subsequently affected calcium channels in the body wall and muscle, disrupting their structure; it serves as an uncoupling agent to interfere with ATP synthase. Moreover, DMDS based on the fumigation mode entered the body through the respiratory pathway of olfactory perception-oxygen exchange and subsequently affected calcium channels in the nerve; eventually, DMDS acted on complex IV or complex I.