Volatilome of the maize phytopathogenic fungus Fusarium verticillioides : potential applications in diagnosis and biocontrol

Abstract

BACKGROUND: Fusarium verticillioides is a maize fungal phytopathogen and a producer of volatile organic compounds (VOCs) and fumonisin B1 (FB1). Our aim was to study the volatilome, conidial production, ergosterol and FB1 biosynthesis in maize cultures over a 30-day incubation period (5, 10, 15, 20, 25, 30 days post inoculation [DPI]). The effect of pure VOCs on the same parameters was then evaluated to study their potential role as biocontrol agents.RESULTS: In total, 91 VOCs were detected, with volatile profiles being more similar between 5 and 10 DPI compared with 15, 20,25 and 30 DPI. Ergosterol content increased steadily with incubation time, and three growth stages were identified: a lag phase(0 to 15 DPI), an exponential phase (15 to 20 DPI) and a stationary phase (20 to 30 DPI). The maximum concentration of FB 1 was detected at 25 (0.030 ∼g FB 1 /∼g ergosterol) and 30 DPI (0.037 ∼g FB 1 /∼g ergosterol), whereas conidial production showed amaximum value at 15 DPI (4.3 ± 0.2 × 105 conidia/∼g ergosterol). Regarding pure VOCs, minimal inhibitory concentration values ranged from 0.3 m M for 4-hexen-3-one to 7.4 m M for 2-undecanone. Pure VOCs reduced radial growth, conidial production and ergosterol and FB1 biosynthesis.CONCLUSIONS: The marked resemblance between VOC profiles at 5 and 10 DPI suggests that they could act as early indicators of fungal contamination, particularly 4-ethylguaiacol, 4-ethyl-2-methoxyanisole, heptanol and heptyl acetate. On the other hand, their role as inhibitors of fungal growth and FB1 biosynthesis prove their great potential as safer alternatives to control phytopathogenic fungi.