wheat infected by the Karnal bunt pathogen In

Multiple defense reactions triggered in plants dur-ing invasion of the pathogen or by other stress induc-ing agents are well established. Among those defences, considerable attention has been given to those induced in plants from the synthesis of pathogenesis related proteins like /3-1,3-glucanase (3). As a lytic enzyme, this enzyme acts on /3-1,3- glucan to digest the cell wall of invading fungal pathogen and releases oligosac-charide elicitors that elicit production of phytoalexins in the infected tissues. Equal emphasis has been given on the hypersensitive reaction (HR) that occurs in most of the resistant plants against pathogens as a first step of defense mechanism (11). In order for HR to occur as a form of programmed cell death or "apoptosis", a sequential protein synthesis takes place via lipid peroxidation accompanied by the enzyme lipoxygenase (LOX) during pathogenestis (6). LOX is also known to be involved in direct inhibition of the growth and de-velopment of invading pathogen and in induction of phytoalexin accumulation (2). The present study was aimed to evaluate the be-havior of these two defence related enzymes in resis-tant and susceptible genotypes of wheat during Kamal bunt infection. Two genotypes of Dread wheat (Triticum aestivum L.) HO 29 (HO 2160-HO 1949- HO 1944/HO 2136) a highly resistant and WL 711 (S 308 x Chris/ Kalyansona) a highly susceptible to Kamal bunt and one highly resistant durum wheat (T durum Oesf.), OWL 5023 (CRILOSIPLC/GARZA) were used in this study. A highly sporulating, aggressive isolate KB-2 of N. indica was cultured from the wheat cultivar W