Interactions between Nectria inventa, a destructive mycoparasite, and fourteen fungi associated with rapeseed

Abstract

Interactions between Nectria inventa and each of 14 fungi isolated from rapeseed were studied. Alternaria brassicae, Pleospora sp. and Trichothecium roseum were most susceptible to N. inventa , followed by Ulocladium atrum and Alternaria raphani . In general, hyphae of N. inventa grew preferentially toward susceptible fungi and, upon contact with its hosts, it formed appressorium-like bodies and hyphal coils. Penetration by N. inventa occurred only in some hosts. In susceptible fungi, granulation of cytoplasm was the first visible response and, in some hosts, wound plug-like reaction zones developed below the point of contact by the parasite hypha. Vacuolation of host cytoplasm occurred commonly in the later stages of parasitism and the infected host cells eventually appeared to be empty.