Premier Biocontrol Traits of Pseudomonads: Siderophores, Phenazines or What Else?

Abstract

Green revolution increased agricultural yields, but indiscriminate use of agrochemicals stagnated productivity and developed resistance among the pests. This provoked to search for effective biocontrol agents as a substitute to chemical pesticides. Among many biocontrol agents, ubiquitous pseudomonads can suppress plant diseases by inhibiting phytopathogens and promote plant growth. Pseudomonads possess a variety of traits that make them an appropriate biocontrol agent. The antimicrobial substances like hydrogen cyanide, 2,4-diacetylphloroglucinol, phenazines, pyoluteorin, pyrrolnitrin, cyclic lipopeptides, etc. produced from pseudomonads are known to suppress fungal pathogens. Moreover, siderophores from pseudomonads also indirectly suppress fungal pathogens by making iron unavailable for their growth due to its chelation. The biosurfactants and hydrolytic enzymes from pseudomonads also support biocontrol mechanisms. Looking towards the overall importance of pseudomonads, the role of their metabolites in disease suppression is discussed here along with the effect of environmental factors and safety aspects.