Light regulation of fumonisin biosynthesis in Fusarium proliferatum and Fusarium verticillioides

Light is an important environmental signal which influence many different physiological responses such as pigmentation, sexual development, asexual conidiation, the circadian clock and secondary metabolism. Our studies about light regulation on metabolic pathways in fungi proved that light of specific wavelength and intensity influences fungal growth and mycotoxin production. In Fusarium proliferatum light generally 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. Wavelengths from both sides of the spectrum, from long (627 nm) to short wavelength (470-455 nm) had a stimulating effect on fumonisin biosynthesis: fumonisins B1 and B2 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. In Fusarium verticillioides wavelengths from red (627 nm) to blue (470-455 nm) stimulated the growth and increased the fumonisin production, by up to 150 % over dark incubation. On the contrary if the intensity of the 455 nm blue light increased from 200 to 1700 lx, the fumonisins 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. In both these Fusarium spp Real time reverse transcriptase analysis showed a correlation between fumonisins biosynthesis and FUM gene expression. These findings demonstrated a role of light on the growth and the modulation of fumonisin biosynthesis and provide new information on the physiology of important toxigenic pathogens.