Differential behaviour of sclerotia and hyphae of Rhizoctonia solani on leaf, stem and root surfaces of SR1 tobacco plants compared with behaviour on artificial growth media

摘要

Rhizoctonia solani Kuhn., a devastating necrotrophic pathogen, causes various diseases on tobacco (Nicotiana tabacum L.) seedlings as well as on adult plants leading to significant crop loss. The goal of this study was to study differential behavior of the fungus on its host surface versus an artificial growth media. Behaviour of sclerotia of R. solani and hyphae emerging from germinated sclerotia were studied on leaf, stem, and root surfaces of SR1 tobacco plants and compared with that observed on artificial growth media. This behavior was analyzed in terms of the time of germination sclerotia, growth of hyphae on surfaces of different plant organs and branching pattern of hyphae on leaves. Sclerotia of R. solani showed comparatively slower germination on the surface of SR1 tobacco leaves than media. Growth of hyphae emerging from germinating sclerotia was found to be significantly less on the surfaces of leaves. Among different parts of SR1 tobacco plants highest hyphal growth was found on leaves and lowest on stem at 24 hpi. Branching pattern of R. solani hyphae on artificial media was more complex with higher amount second and third degree branches compared to SR1 tobacco plants. The differential behaviour of hyphae of R. solani on different parts of SR1 tobacco plants versus on media was likely due to non-availability of ready nutrients compounded with defense structures or chemicals present of the host surface.