Fungal suppression of resistance against inappropriate Blumeria graminis formae speciales in barley, oat and wheat

摘要: When barley, wheat or oat leaf epidermal cells were attacked by their appropriate forma specialis (f.sp.) of Blumeria graminis DC. Speer (f.sp. hordei, tritici and avenae, respectively), many attempted penetrations succeeded, functional haustoria formed very few plant died. either the two possible inappropriate ff.spp., penetration attempts failed in association with papilla deposition cells, died, if visible cell died soon afterwards. Double inoculation experiments performed where each cereal species was first its f.sp., as inducer, later different ff.spp. challenger. Infection inducer profoundly affected cellular responses to challenger attack. Suppression defensive dramatic within containing haustorium, evident some extent adjacent but undetectable at distance. resistance allowed most attacks, even form a haustorium. Furthermore, death penetrated also suppressed so that functioned support colony development. In oat, delayed prevented full development barley wheat, no apparent four days after colonies produced extensive hyphae, secondary conidial chains.