Unlocking the Role of Rice Root Metabolites in Modulating Meloidogyne graminicola Chemotaxis

Understanding the chemotactic crosstalk between rice and root-knot nematodes is essential for developing sustainable pest management strategies. Rice plants release chemicals that can modulate the behavior of the rice root-knot nematode Meloidogyne graminicola, a major plant-parasitic nematode. In this study, two rice cultivars, Pusa Basmati 1121 (nematode-susceptible) and Kalo Bhutia 213 (highly nematode-resistant), were used to collect metabolites released from rice roots, and their role in influencing rice-M. graminicola interactions was studied. Olfactometer studies using whole plant roots confirmed that M. graminicola was significantly more attracted to PB 1121 compared to KB 213. Attraction assays with intact roots under choice and no-choice conditions corroborated these findings. Root exudates were extracted in ethyl acetate, and volatile organic compounds (VOCs) from roots extracted in hexane were analyzed using GC-MS. Metabolite analysis through PCA, PLS-DA, heat maps, and pathway enrichment was carried out to distinguish cultivar-specific responses. Discriminant analysis revealed significant bioactive metabolites modulating nematode chemotactic behavior. These bioactive semiochemicals offer a promising avenue for developing cost-effective and environmentally sustainable solutions for nematode management in rice cultivation.