Gene-based approach for selection of plant-growth-promoting Rhizobacteria for plant disease control

Plant-growth-promoting rhizobacteria (PGPR) have multiple modes of action to benefit plant health. They promote plant growth by producing auxins and an enzyme, 1-aminocyclopropane-l-carboxylic acid deaminase (ACCD), which mediate high accumulation of stress ethylene. Further, they have been studied as potential biocontrol agents from the perspective of reducing pathogen infection in plants. They directly inhibit deleterious microorganisms by production of an array of antibiotics (2,4 DAPG, phenazine, iturin, surfactin, fengycin, bacillomycin) and indirectly reduce disease development by inducing defence molecules in plants. Thus, it is conceived that knowledge of genes responsible for plant growth and biocontrol activity could be a boon in selecting elite PGPR strains for the control of plant diseases. Current molecular biology techniques allow characterization of the genes responsible for plant health associated traits of PGPR. The use of candidate genes in selection of PGPR strains for the control of plant diseases is reviewed in this paper.