Influence of light on growth, fumonisin biosynthesis and FUM1 gene expression by Fusarium proliferatum.

Fumonisins are a group of mycotoxins, mainly found in maize and maize-based food and feed, associated with several diseases in animals. The impact of these toxins on the economy and health worldwide has driven several efforts to clarify the role of environmental factors that can influence fumonisin biosynthesis by the toxigenic species. We analyzed the influence of light of varying wavelength on growth and fumonisin biosynthesis by the fungus Fusarium proliferatum ITEM 1719. Light in general had a positive influence on growth, with a mean increase of the grow rate of about 40% under light exposure in comparison to the dark incubation. Wavelengths from both sides of the spectrum, from long (627 nm) to short wavelength (470-455 nm) had a stimulating effect on fumonisin biosynthesis compared to the dark incubation: fumonisins B(1) (FB(1)) and B(2) (FB(2)) production increased of about 40 fold under red, 35 fold under blue, 20 fold under royal blue, 10 fold under green, 5 fold under yellow and 3 fold under white light in comparison to the dark incubation. The transcriptional regulation of the FUM1 fumonisin biosynthesis gene was analyzed by Real time reverse transcriptase PCR quantification, revealing a correlation between fumonisin biosynthesis and gene expression. These findings show a role of light on the growth and the modulation of fumonisin biosynthesis and provide new information on the physiology of an important toxigenic maize pathogen.