Influence of light on growth, fumonisin biosynthesis and FUM1 gene expression by Fusarium proliferatum Francesca Fanelli a , Markus Schmidt-Heydt b , Miriam Haidukowski a , Rolf Geisen b , Antonio Logrieco a , Giuseppina Mulè a, ⁎ a Institute of Sciences of Food Production, CNR, via Amendola 122/0, 70126 Bari, Italy b Max Rubner Institut, Department for Safety and Quality of Fruit and Vegetables, Haid-und-Neu-Str. 9, 76131 Karlsruhe, Germany abstract article info Article history: Received 5 July 2011 Received in revised form 26 September 2011 Accepted 23 October 2011 Available online 15 November 2011 Keywords: Fumonisin Fusarium proliferatum Light FUM1 Real time RT-PCR 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 biosyn- thesis 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 incuba- tion. 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 tran- scriptional regulation of the FUM1 fumonisin biosynthesis gene was analyzed by Real time reverse transcrip- tase 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. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Fusarium proliferatum belongs to the Liseola section of the Fusarium genus (Nelson et al., 1983), and its teleomorph, Gibberella intermedia, belongs to the G. fujikuroi complex, composed of at least 13 repro- ductively isolated biological species (mating populations) (Leslie and Summerell, 2006; Scauflaire et al., 2011; Van Hove et al., 2011). Fusari- um proliferatum is a causal agent of diseases of various economically im- portant plants such as maize, banana and other hosts including pine trees, asparagus, wheat and barley. The distribution on maize of this species is particularly significant in Southern Europe (Logrieco et al., 2002; Jurado et al., 2004) though it has been recorded also in Nepal (Desjardins et al., 2000) and Mexico (De Souza and Formento, 2004). Fusarium proliferatum produces different mycotoxins, including monili- formin (Marasas et al., 1984), beauvericin (Logrieco et al., 1998), fusaric acid (Bacon et al., 1996), fusaroproliferin (Ritieni et al., 1995) and fumo- nisins (Ross et al., 1990). Fumonisins are a group of mycotoxins associated with several mycotoxicoses, including equine leukoencephalomalacia, porcine pulmonary edema and experimental kidney and liver cancer in rats (Howard et al., 2001). They are divided into four groups: A, B, C and G, with the B-type fumonisins being the most toxic. Generally, FB 1 makes up approximately 70%, and FB 2 and FB 3 each make up about 10–20% of the total fumonisin content (Nelson et al., 1993). The fumonisin biosynthetic gene cluster (FUM) has been identi- fied in several fumonisin producers (Brown et al., 2007; Pel et al., 2007; Proctor et al., 1999, 2008). A comparative genomic approach was used in F. proliferatum (Waalwijk et al., 2004) to determine the presence of the FUM cluster, revealing the same order and orientation of genes described for F. verticillioides and F. oxysporum (Proctor et al., 2003, 2008). The cluster gene FUM1 encodes a polyketide synthase which would catalyze synthesis of the linear polyketide of fumonisins. The encoded FUM1 (previously FUM5) polyketide synthase sequence of F. proliferatum shows 85% identity with F. verticillioides (Waalwijk et al., 2004). The low level of identity (77–89% at amino-acid level) of FUM genes and the different genomic locations of the cluster in F. verticillioides and F. proliferatum indicate that each species may have acquired the cluster independently (Waalwijk et al., 2004). In F. proliferatum many environmental and abiotic factors, such as temperature, water activity and solute potential, have been found to affect fumonisin biosynthesis (Kohut et al., 2009; Samapundo et al., 2005; Marín et al., 2010), even though a high variability in phenotypic fumonisin biosynthesis has been reported. International Journal of Food Microbiology 153 (2012) 148–153 ⁎ Corresponding author. Tel.: + 39 080 5929329; fax: + 39 080 5929374. E-mail address: giuseppina.mule@ispa.cnr.it (G. Mulè). 0168-1605/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.ijfoodmicro.2011.10.031 Contents lists available at SciVerse ScienceDirect International Journal of Food Microbiology journal homepage: www.elsevier.com/locate/ijfoodmicro