Hydrolytic Enzymes from PGPR Against Plant Fungal Pathogens

Abstract

AbstractFungal and oomycete pathogens are the significant causes of many plant diseases leading to major annual economic loss. This results in today’s shortfall of food supply due to which many millions of lives are insufficiently fed. One way to combat the loss is use of fungicides, but repeated use of fungicides resulted in evolved resistance in these pathogens leading to severe loss of yield. Hence, biological methods are proving to be more beneficial as compared to the chemical ones. Plant growth-promoting rhizobacteria (PGPR) employ a variety of mechanisms to promote plant growth and development, of which production of various hydrolytic enzymes against the fungal pathogens plays an important role. PGPR as biocontrol agents have been tried in many plants. Recently vast studies referring to the isolation and characterization of these hydrolytic enzymes have determined their ability to control plant pathogens. Enzymes like protease, chitinase, cellulose, and glucanase are known to act on the fungal cell wall leading to its degradation and finally the lysis of the fungal cell. Many bacterial species like B. subtilis, B. cereus, B. subtilis, B. thuringiensis, S. marcescens, R. solani, F. oxysporum, S. rolfsii, P. ultimum, etc. are shown to synthesize such enzymes that can affect the cell wall integrity of the pathogens and inhibit them. These hydrolytic enzymes produced by PGPR play an important role in the control of various plant pathogens and thereby improve the plant growth, making an efficacious biocontrol agent. These PGPR release their antifungal metabolites in a sustained manner due to which it is difficult for the target organism to develop resistance against them as it is experienced with the chemical fungicides. PGPR can be used individually or in combinations in the sector of plant growth and protection.KeywordsBiocontrol agentsFungiHydrolytic enzymesOomycetesPhytopathogens