LAUSR

Upon pathogen attack, the plant defence response is mediated by a set of connected signal transduction pathways. Experiments were conducted to observe the role of plant hormone, in particular gibberellin (GA), in the response of rice to infection by the migratory internal tissue infecting (endoparasitic) root-rot nematode Hirschmanniella oryzae. Exogenous application of GA was done several times on Nipponbare, and there was significant effect of GA in reducing infection in Nipponbare against H. oryzae. A significantly higher number of H. oryzae per plant was found in GA-deficient mutant waitoC compared to WT and a lower number in GA-insensitive mutant gid1-3 plants. Both the number of nematodes/plant and the number of nematodes/g of root were significantly higher in waitoC than gid1-3. The results indicated that low levels of GA (naturally present) were needed for successful infection in rice plant by H. oryzae, but high levels were inhibitory.