Induction of defence-related enzymes in onion by combined application of fungal and bacterial biocontrol agents against Fusarium oxysporum f. sp. cepae.

Basal rot disease of onion is a major problem in different onion growing regions of Tamil Nadu, India. Fungal and bacterial cultures were isolated and tested their efficiency againstFusarium oxysporumf. sp.cepaeunderin vitroconditions. Effective bacterial and fungal antagonists were tested alone and in combinations for the control ofF. oxysporumf. sp.cepaein glasshouse experiments. Defence-related enzymes such as peroxidase, polyphenol oxidase and phenylalanine ammonia-lyase were induced and accumulated in onion treated with fungal and bacterial antagonists. Defence-related enzymes were significantly higher in onion pretreated with consortial formulation of Pf12 + Pf27 + TH3 at 5 days after the challenge inoculation withF. oxysporumf. sp.cepaeand gave resistance to onion against basal rot disease. [ABSTRACT FROM AUTHOR]