Induction of chitinases and beta-1,3-glucanases in resistant and susceptible cultivars of sorghum in response to insect attack, fungal infection and wounding

Sorghum genotypes that differ in their resistance to the fungus, Fusarium m oniliforme or aphids were analyzed for their response to stress induced by infection with the fungus, by feeding injury due to insect pests, or by mec hanical wounding. The pathogenesis-related (PR) proteins, chitinases and be ta-1,3-glucanases, were induced in the plant tissues in all inbreds under a ll three stress conditions. However, there were differences in the response s of the individual inbreds and in the extent and duration of the induction of these enzymes by the three stress conditions. In general, both suscepti ble and resistant inbreds had higher levels of the enzymes especially at la te times after exposure to the insects. The induced enzyme activities were found in the apoplastic space and intracellular locations, but the distribu tion varied depending on the genotype and the stress employed. (C) 1999 Els evier Science Ireland Ltd. All rights reserved.