Evaluation of mycoparasitic efficacy of nematode-trapping fungi against Rhizoctonia solani inciting sheath blight disease in rice (Oryza sativa L.)

Sheath blight incited by Rhizoctonia solani is an important rice disease that constitutes a major challenge to rice production worldwide. Nematode-trapping fungi possess the ability to capture, kill and digest the nematodes. However, the ability of many nematode-trapping fungi parasitizing the soil borne plant pathogens may fillip the gap towards maximum exploitation of these fungi in biological control strategy. In present study, we have investigated the mycoparasitc potential of Arthobotrys conoides, A. eudermata, Dactylellina gephyropaga and D. phymatopaga against Rhizoctonia solani in in vitro and rice plants grown under green house conditions. We found that Arthobotrys conoides, A. eudermata and Dactylellina gephyropaga started forming coils around hyphae of Rhizoctonia solani within 24 h of hyphal interaction. A. eudermata was found highly mycoparasitic on all isolates of R. solani followed by A. conoides and D. gephyropaga. Dactylellina phymatopaga failed to parasitize any isolates of R. solani. At the site of coiling, a strong cell wall proliferation was observed in Rhizoctonia cells and the cytoplasm of these cells subsequently disintegrated. Treatment of R. solani infested soils with colony forming units of A. eudermata, A. conoides and D. gephyropaga decreased sheath blight infection in rice fillers by 43.39-50.74% as compared to non-treated but R. solani inoculated plants.