Influence of light on growth, conidiation and fumonisin production by Fusarium verticillioides.

Light is a very important signal for fungi since it influences many different physiological responses. We analyzed the influence of light of varying wavelength and intensity on growth, conidiation and biosynthesis of fumonisin B(1) (FB(1)), B(2) (FB(2)), and B(3) (FB(3)) by Fusarium verticillioides ITEM 10027. Wavelengths across the visible spectrum, from red (627 nm) to blue (470-455 nm), stimulated the growth and increased the fumonisin production, by up to 150 % over dark incubation. If the intensity of the 455 nm blue light increased from 200 to 1700 lx, the fumonisin biosynthesis decreased. Incubation under a short wave blue light (390 nm) showed reduced fungal growth and fumonisin production by up to 85 %. White pulsing light had no effect on growth but reduced fumonisin production to half of what observed during dark incubation. Real time reverse transcriptase (RT)-PCR was used to measure the expression level of Fum1, Fum21 and FvVE1 transcripts, which encode proteins involved in fumonisin biosynthesis. There was a significant correlation between gene expression and fumonisin production.