Microbial biomolecules: reducing viral loads in agriculture

Plant viruses have been considered one of the most critical pathogens, given their leading to severe economic losses in crop yield quality and often reducing the productive life of the agricultural land. Plant viral disease management primarily depends on the genetic resistance of host plants and their environment. The increasing demand for crop production with a significant reduction of synthetic chemical fertilizers and pesticide use in the field—given their application causes extensive damage to the fertility of the soil—is a big challenge nowadays. The use of biomolecules in the form of microbes to reduce viral loads in agriculture has emerged as a boom in the agricultural field. Kloepper and Schroth, in the year 1981, for the first time, demonstrated how the microbial population in the rhizospheres favors plant growth by colonizing the roots of plants and appeared to show plant growth-promoting activity, which later came to be very commonly stated as plant growth-promoting rhizobacteria (PGPR) aiding potential environment-friendly alternatives to chemical fertilizers. Several specific strains of PGPR have been reported to suppress diseases by acting as the antagonism between the bacterial and viral pathogens and induce systemic resistance in plants by providing plants with beneficial effects like enhancement in growth effect through additional secretion of growth factors, hormones, vitamins, etc. Hence, this chapter will provide an overview of the mechanism of PGPR to reduce the viral loads in agriculture and show how viruses antagonize this cellular stress response to reduce its harmful effects on plant growth.