Expression analysis of defence related genes and histopathological changes in direct seeded rice genotypes (Oryza sativa L.) against root-knot nematode (Meloidogyne graminicola)

The root-knot nematodes, Meloidogyne spp. are one of the most important diseases causing organisms in direct seeded rice. In order to gain insight of differential response of susceptible and resistant rice cultivars upon nematode infection, expression of OsEDS1, OsPAD4 and OsWRKY genes involved in plant innate immunity was investigated. The expression analysis showed that EDS1-and PAD4mediated SA-upstream signaling triggered the induced defense at an the early stage of infection i.e., 2dpi and 6dpi in the resistant rice variety NDR-97, while it was negatively regulated in the susceptible genotype PB-1121. The histopathological studies of root galls of susceptible and resistant plants showed significant differences in the development of females, giant cells and egg production. The fecundity of the nematode was suppressed in the resistant cultivars.