Facets of rhizospheric microflora in biocontrol of phytopathogen Macrophomina phaseolina in oil crop soybean.

The use of microbial bioinoculants for managing plant diseases and promoting plant growth is an effective alternative approach to integrated farming. One of the devastating phytopathogens is Macrophomina phaseolina (Tassi) Goid. It is an omnipresent fungus infecting more than 500 plant species. It causes charcoal rot disease in soybean leading to 30-50% yield loss. Soybean Glycine max (L.) oil seed crop produced globally is highly susceptible to M. phaseolina. India is the fifth largest producer of soybean in the world. Madhya Pradesh is the largest soybean-producing state in India; Around 70% yield loss of soybean is accounted to M. phaseolina infection in India. Control of charcoal rot is the requisite of the current situation. Chemical control is not feasible due to saprophytic nature and prolonged survival of Macrophomina phaseolina. Chemical fungicides are expensive, toxic, hazardous, and cause pollution. Biological control is an effective approach to control this devastating fungus. The rhizosphere of soil is rich in beneficial microflora competent to suppress plant pathogens and also promote plant growth. PGPR have well-developed mechanisms that impart antagonistic traits to them. PGPR produces various antifungal metabolites siderophores and HCN which inhibit fungal growth, and can be used as potent BCA. Pseudomonas and Bacillus species have been reported effective against M. phaseolina. The mechanisms and antifungal compounds produced by these bacteria to control charcoal rot can be studied extensively. BCA or the metabolites secreted by them have the potential to develop effective bioformulations for soybean at the commercial level for sustainable agriculture.