Evaluation of Resistance in Direct Seeded Rice (Oryza sativa L.) against Meloidogyne graminicola

In India, the rice root knot nematode, Meloidogyne graminicola is the dominant species infecting rice-wheat cropping system due to its broad host range and ability of causing potential yield loss. It has become an emerging problem in the nurseries and upland rice. Second stage juveniles (J2s) penetrate the roots closely behind the root tip; migrate to vascular cylinder turning it into multinucleated giant cells, by endomitosis and cell hypertrophy characterized by hook shaped galls. In the present study, 33 direct seeded rice (DSR) genotypes of Asian rice (Oryza sativa) were evaluated for resistance against rice root-knot nematode, M. graminicola on the basis of root-knot index and multiplication factor. Out of the total 33 rice cvs, 6 cultivars had less than10 galls/plant and of these, cv. NDR-97 exhibited a strong resistant response with least number of galls (1.5galls/plant) and remaining are moderately and highly susceptible. The most and least susceptible cultivars were selected for further histopathological and differential gene expression studies.