β-1,3-glucanase and chitinase activities and the resistance response of wheat to leaf rust

To investigate the role of beta -1,3-glucanases (EC 3.2.1.39) and chitinases (EC 3.2.1.14) in the resistance response of wheat (Triticum aestivum L.) to leaf rust (Puccinia recondita f. sp. tritici), their intercellular activities were studied in resistant (Karee/Lr35) and susceptible (Karee) near-isogenic wheat lines under conditions of infection and non-infection. Resistance was associated with high constitutively expressed chitinase activity and induced beta -1,3-glucanase activity. At 168 hours postinoculation several infection sites on Karee/Lr35 displayed necrosis, confirming a hypersensitive response, whereas similar necrotic lesions were observed only for a limited number of infection sites on Karee at that sampling stage. The possible role of chitinases and beta -1,3-glucanases in the hypersensitive defence response of wheat to leaf rust is discussed.