Induction of defense-related enzymes and enhanced disease resistance in maize against Fusarium verticillioides by seed treatment with Jacaranda mimosifolia formulations

AbstractFusarium verticillioidesis an important fungal pathogen of maize, causing stalk rot and severely affecting crop production. The aim of this study was to characterize the protective effects of formulations based onJacaranda mimosifolialeaf extracts againstF. verticillioidesin maize.We compared different seed treatments comprisingJ. mimosifoliaextracts, chemical fungicide (mefenoxam) and salicylic acid to modulate the defense system of maize host plants. Both aqueous and methanolic leaf extracts ofJ. mimosifolia(1.2% w/v) resulted in 96–97% inhibition of mycelial growth ofF. verticillioides. While a full-dose (1.2%) extract ofJ. mimosifoliaprovided significant protective effects on maize plants compared to the inoculated control, a half-dose (0.6% w/v) application ofJ. mimosifoliain combination with half-strength mefenoxam was the most effective treatment in reducing stalk rot disease in pot and field experiments. The same seed treatment significantly upregulated the expression of genes in the leaves encoding chitinase, glucanase, lipid transfer protein, and pathogenesis-related proteins PR-1, PR-5 and PR-10, 72 h after inoculation. This treatment also induced the activities of peroxidase, polyphenol oxidase, protease, acid invertase, chitinase and phenylalanine ammonia lyase. We conclude that seed pre-treatment withJ. mimosifoliaextract with half-strength chemical mefenoxam is a promising approach for the management of stalk rot in maize.