The Influence Of Different Environmental Factors On The Fumonisin Production And FUM Gene Expression In Fusarium Verticillioides

The corn is one of the three major crops in the world, which is also a major food and feed crop in our country. Maize ear rot is a serious disease affecting its production and quality. Fumonisins(FBs) produced by ear rot pathogens have a strong impact on corn edibleness and marketability. Fumonisins are carcinogenic mycotoxins biosynthesis by F. verticillioides and F.proliferatum as secondary metabolites. FBs not only induce the fatal disease syndromes:equine leukoencephalomalacia and porcine pulmonary edema, but also have been linked with an increased risk of esophageal cancer in humans. Based on their toxicity, FB1has been classified by International Agency for Research on Cancer (IARC) as possibly carcinogenic in humans. In this paper, through trial and error to verify the the rule and its extraction method of Fverticillioides biosynthesis fumonisin on PDA medium. The article also measured GS-1for optimal growth and the relationship between fumonisin production and FUM gene expression under different temperatures and water activity and different concentrations of pesticides. The results were as follows:Determining the F.verticillioides culture on PDA10days, fumonisins in media content to the highest point. And acetonitrile/water (V:V=3:1) as solvent, then concentrated under60℃nitrogen blowing. And initially identified the fumonisin produced by F.verticillioides dissolved in the medium, a small portion remaining in the mycelium. Under different temperature and water activity conditions, GS-1for optimal growth and production of fumonisin conditions are30℃and a water activity of0.99, then showed the mycelial growth and toxin production are more closely linked. At different concentrations of difenoconazole and tebuconazole, GS-1mycelial growth diameter is reduced with two pesticide concentrations were increased, showed high concentrations of pesticides have high inhibitory on the growth of F.verticillioides. EC50values were calculated based on formulas, by comparing the results, the tebuconazole has higher virulence than difenoconazole for F.verticillioides. Under different concentrations of difenoconazole and tebuconazole conditions, GS-1fumonisin biosynthesis performance inhibition or enhancement trend. Under the concentration range of difenoconazole of0.5μg/g-4μg/g, with the increase of pesticide concentration, the amount of strain produce fumonisin FB1and FB2showed a decreasing trend, the inhibition enhanced. But when the concentration of difenoconazole is0.25μg/g, the concentration of FB1and FB2is below the high difenoconazole treatment, that this concentration of difenoconazole has a high ability to inhibit strains to produce fumonisins than other test concentrations. After various test concentrations of tebuconazole treatment, except the concentration of0.25μg/g, the other concentrations, showed inhibition for GS-1fumonisin biosynthesis. High concentrations of tebuconazole has a strong inhibitory for the GS-1to produce the FB1and FB2. But when the concentration of tebuconazole is0.25μg/g, GS-1’s ability to produce FB1and FB2actually strengthened. The results for FUM gene expression analysis showed that, under different conditions of temperature and water activity, the gene FUM1, FUM21has the lowest expression level under32℃and a water activity of0.99. While the FUM19under30℃and at a water activity of0.99has the lowest expression level, and close to the water activity of0.99and temperature of32℃. The gene FUM1and FUM21has the higest expression level under32℃and a water activity of0.95, and is nearly3times and2times than lowest expression levels. The gene FUM19has the higest expression level under30℃and at a water activity of0.95, the highest expression is two times than the lowest expression levels. Under various concentrations of difenoconazole culture conditions, the gene FUM1has the lowest expression under1μg/g, the gene FUM19and FUM21has the lowest expression under4μg/g. Three genes has the highest expression under the concentration of2μg/g. The highest expression of the FUM1is1.5times of the lowest expression, while FUM19and FUM21is2and1.8times than the lowest expression.Under various concentrations of tebuconazole culture conditions, the gene FUM1and FUM19has the lowest expression under0.5μg/g, the gene FUM21has the lowest expression under0.25μg/g. The FUM1and FUM19has the highest expression under the concentration of0.0625μg/g, is2.1and2.2times of the lowest expression, while and FUM21has the highest expression under the concentration of1μg/g, and is1.3times of the lowest expression.