ACCUMULATION OF PATHOGENESIS-RELATED PROTEINS IN BARLEY INDUCED BY POWDERY MILDEW INFECTION IN THE LATE-STAGE OF COMPATIBLE AND INCOMPATIBLE INTERACTION

Accumulation of apoplastic pathogenesis-related (PR) proteins in inter cellular spaces of barley leaves cv. Ricardo with Mla3 resistance gene was examined 5 and 10 days after inoculation with a virulent and an a virulent race of powdery mildew (Erysiphe graminis f. sp. hordei). The accumulation pattern of PR proteins on day 5 after inoculation was si milar to that on day 3 after inoculation. Only a small increase in the amount of PR proteins but no qualitative differences were observed. T he accumulation pattern of PR proteins was similar in both compatible and incompatible host-pathogen interaction but it was more expressive in the host-parasite incompatibility than in the compatibility. Analys is of accumulation of PR proteins 10 days after inoculation revealed s ignificant differences between compatible and incompatible host-parasi te interactions. While in the incompatible interaction PR proteins wer e detected after 10 days on the same level as after 5 days, in the com patible interaction a significant decrease was observed between days 5 and 10 of infection. Only one of the PR proteins remained on the incr eased level in the compatible interaction on day 10 of infection. It i s possible that their induction in the preparasitic phase of pathogene sis is strongly inhibited in the parasitic phases by a virulent race o f fungi.