Vanillin in Resistant Tomato Plant Root Exudate Suppresses Meloidogyne incognita Parasitism

Tomato (Solanum lycopersicum) plantsare susceptible to infection by root-knot nematodes, which cause severeeconomic losses. Planting resistant tomato plants can reduce nematodedamage; however, the effects of resistant tomato root exudates insuppressing Meloidogyne incognita remaininsufficiently understood. Here, we determined that the resistanttomato plant Lycopersicon esculentum cv. Xianke-8 (XK8) alleviates nematode damage by downregulatingthe expression of the essential parasitic nematode gene Mi-flp-18 to reduce the infection and reproduction of M. incognita. Using gas chromatography-mass spectrometry, we identifiedvanillin as a unique compound (compared to susceptible tomato cultivars)in XK8 root exudates that acts as a lethal trap and inhibitor of egghatching. Moreover, the soil application of 0.4-4.0 mmol/kgvanillin significantly reduced galls and egg masses. The parasitegene Mi-flp-18 was downregulated upon treatment withvanillin, both in vitro and in pot experiments. Collectively,our results reveal an effective nematicidal compound that can usein feasible and economical strategies to control RKNs.

Automated summary

By downregulating the expression of the parasite gene Mi-flp-18, vanillin in the root exudates of resistant tomato plants can alleviate nematode damage and reduce parasitic infection and reproduction. This study reveals an effective nematicidal compound that can be used for feasible and economical strategies to control root-knot nematodes.