Plant disease management with amelioration of systemic resistance in soybean by endophytic fungi associated with GC-MS metabolic profiling of Chaetomium sp.,

Abstract

Plants exhibit beneficial associations between fungal endophytes and roots for better growth, disease suppression, and stress tolerance. Considerable information is now available about the beneficial role of fungal endophytes. In this study, endophytic fungi Chaetomium sp., Curvularia chonburiensis, C. specifera, C. hawaiiensis, Rhizoctonia solani, Fusarium solani, Talaromyces assiutensis and T. trachyspermus isolated and evaluated for nematocidal activity against a root-knot nematode Meloidogyne javanica. The culture filtrates of endophytic fungi were prepared and used to check their efficacy against root knot nematodes. The culture filtrates of endophytic fungi were applied to pot and field experiments using soybean as host plants. In vitro study of these endophytic fungal culture filtrates showed strong nematocidal activity by killing juveniles of M. javanica to a certain degree, while Chaetomium sp., and Talaromyces assiutensis showed 100% mortality rate after 48 h. The application of Cephalosporium sp., Chaetomium sp., Talaromyces trachyspermus and T. assiutensis suppressed root rotting fungi of soybean in both screen house and field plots experiments. Significance of fungal isolates was further confirmed by repeated experiments. Endophytic fungi also showed positive impacts on the host plants by increasing the rate of their growth and improving their tolerance level to biotic stress which was evident by the production of increased amounts of resistance markers like salicylic acid and polyphenol contents with subsequent improvement of the antioxidant status. The n-hexane fraction of the culture filtrate of Chaetomium sp., were subjected to GC-MS analysis for the identification of compounds and some new compounds have been reported for the first time from this fungus. The results will facilitate a better understanding of host plant and fungal interaction and are likely to assist in the screening and utilization of beneficial microbes.