Role of phosphate-solubilizing microbes in the management of plant diseases

Abstract

Soilborne phytopathogens are one of the major problems in sustainable crop production world over. To alleviate the damaging impact of pathogens on crop yields, huge quantities of toxic chemicals especially pesticides are used in modern agronomic practices, which, however, are extremely destructive to the environment. The non-desirability of applying huge quantities of pesticides to soil due in part to residue problems, emergence of resistance among soil phytopathogens, and lack of pathogen-resistant crop varieties has forced researchers to find solutions to the increasing pesticides problems. To this end, biological control measures consisting of microbial preparations are considered a promising option to the use of expensive and environment disruptive pesticides. Microorganisms including plant growth-promoting rhizobacteria (PGPR) in general have been found to synthesize a wide array of metabolites with significant fungicidal and bactericidal capabilities. The use of phosphate-solubilizing (PS) microorganisms among PGPR has produced both direct and indirect effects on growth and development of plants. The PS microbes endowed with biocontrol activity manage the pathogens by one or simultaneous mechanisms of antibiosis, lysis, competition, and myco-parasitism and prevent the yield losses. Even though the literature on the physiological role of PS microorganisms in crop enhancement via P supply is adequately available, the information on the ability of such organisms in the control of phytopathogens is scarce. Here, different mechanisms utilized by PS organisms for plant disease suppression are discussed. It is envisioned that the PS bacteria in the near future are expected to reduce, if not completely eliminate, the use of pesticides in insect-pests management strategies.