Parasitic interactions between Claviceps purpurea strains in wheat and an acute necrotic host response

Abstract

Concurrent inoculation of wheat florets with pairs of distinctive strains of Claviceps purpurea gave ergot sclerotia in which both strains co-existed as indicated by their alkaloid content, the ability to produce the sexual stage and sclerotial morphology. Production of heterogeneous sclerotia may facilitate hybridization of strains during subsequent ascogeny. A strain notable for its parasitic vigour and failure to biosynthesize ergot alkaloids displaced another strain when the second inoculum was introduced around infected ovaries 7 days after initial inoculation. The necrosis of affected spikelets which occurred in response to the interparasitic competition is recognized as a novel phenomenon in ergot-host relationships.