Quantitative detection of Fusarium spp. and its correlation with fumonisin content in maize from South African subsistence farmers

Abstract

A quantitative detection tool was developed to enable the monitoring of fumonisin-producing fungi in food and feed commodities. To this end, a quantitative PCR (TaqMan) was developed that targets a conserved region in the polyketide synthase gene fum1, which is involved in the biosynthesis of fumonisin. Hence, this method specifically detected isolates from the fumonisin-producing species Fusarium verticillioides, F. proliferatum, F. nygamai and F. globosum whereas isolates of the fumonisin non-producing species F. equiseti, F. graminearum, F. oxysporum, F. semitectum and F. subglutinans that commonly occur on maize were not detected. Moreover, a few fumonisin non-producing F. verticillioides isolates did not generate any fluorescent signals and were therefore not detected. The correlation between quantitative PCR and mycotoxin content was determined using field samples collected at homestead farms in South Africa. Among 40 samples from the Eastern Cape collected in 2005 a good correlation (R2=0.8303) was found between pg fungal DNA and fumonisin content. A similar correlation (R2=0.8658) was found among 126 samples collected from four provinces in South Africa in 2007. These observations indicate that samples containing ≥ 40 pg fungal DNA/mg sample are suspected of also exceeding the 1 mg/kg total fumonisin level and therefore do not comply with the European Commission limit for fumonisins B1+B2 for maize intended for direct human consumption that applies from 1 October 2007. Combined with the very high maize intake, our results indicate that fumonisin levels in maize from South African homesteads regularly exceed the tolerable daily intake for fumonisins.

Correlation betweenFusarium graminearumand deoxynivalenol during the 2012/13 wheat Fusarium head blight outbreak in Argentina

“…TaqMan reactions were performed in 25 µl, using 12.5 µl of TaqMan universal PCR master mix (Applied Biosystems) and 100 nM of FAM-labeled target and internal control probe and 400 nM of forward and reverse primer for both the target F. graminearum (Waalwijk et al 2004(Waalwijk et al , 2008 as well as the internal positive control (Klerks et al 2004). TaqMan reactions were performed on 2 µl of DNA preparations from samples.…”

<i>Fusarium</i> spp. and levels of fumonisins in maize produced by subsistence farmers in South Africa

“…that produce fumonisins using primers and probes designed for the polyketide synthase gene fum1. 24 qPCR was performed using a MicroAmp Optical 96-well reaction plate and MicroAmp Optical Caps (Applied Biosystems, Foster City, USA). An ABI Prism 7700 Sequence Detection System (Applied Biosystems) was used to perform the PCR and assess fluorescence.…”

Fumonisins and related Fusarium species in pre-harvest maize ear rot in Poland

“…In Eastern and Southern Africa fumonisin B 1 was detected at concentrations ranging from 0.002 to 1.91 mg kg -1 (92.5% positive samples), while the sum of fumonisin (B 1 + B 2 + B 3 ) concentrations in the same samples ranged from 0.002 to 2.73 mg kg -1 . The results of frequent fumonisin occurrence at a high level combined with very high maize intake indicated that FB s levels in maize from Africa regularly exceed the tolerable daily intake for fumonisins (Waalwijk et al 2008). These are alarming quantities in particular taking into account the maximum recommended levels of this toxin according to the guidance values.…”