Antagonistic mechanisms of fluorescent pseudomonads against Phytophthora capsici in black pepper (Piper nigrum L.)

Abstract

Fluorescent pseudomonads were selectively isolated from black pepper (Piper nigrum L.) roots and screened for volatile and non-volatile metabolite production and inhibition in growth of Phytophthora capsici, the casual organism of foot rot disease. Among the isolates tested, the inhibition of P. capsici varied from 36.3% to 70.0% by non-volatile metabolites and from 2% to 23% by volatile-metabolites. Isolate IISR-51 caused maximum inhibition of P. capsici by production of non-volatile and volatile metabolites. Many of the isolates produced hydrogen cyanide, which limited the growth of P.capsici. The study indicated the involvement of siderophore-mediated antagonism in fluorescent pseudomonads. The fluorescent pseudomonads could systemically invade black peppercuttings upon root bacterization