Fumonisin producing Fusarium spp. and fumonisin contamination in commercial South African maize

Abstract

Fumonisins are secondary, carcinogenic metabolites produced primarily by Fusarium verticillioides and Fusarium proliferatum on maize worldwide. The natural occurrence of fumonisin-producing Fusarium spp. and fumonisin contamination of maize grain were quantified in selected maize cultivars from principal production areas of South Africa. Grain colonization by Fusarium spp. was determined using quantitative real-time PCR (qPCR) and contamination with fumonisins using HPLC analysis. Kernels from the 2007 samples were also plated onto Fusarium selective medium and subsequently, split plates containing PDA & CLA. The number of fumonisin producing Fusarium spp. were quantified and microscopically identified after 14 days. Simple linear regression analysis was used to determine the relationship between target DNA, fumonisins and the number of fumonisin producing Fusarium spp. using the plating out method. Results indicated high natural infection by fumonisinproducing Fusarium spp. and fumonisin concentrations in warmer production areas such as Northern Cape, North West and Free State Provinces. Spearman Ranking Correlations indicated that the responses of cultivars to colonization of grain by fumonisin producing Fusarium spp. varied over localities/seasons (r s =0.42 to 0.64) suggesting that cultivars reacted differently to different environmental/inoculum conditions (disease potentials). Cultivars CRN3505 and DKC80-12B showed a degree of resistance to fungal infection. As with fungal colonization, Spearman Rank Correlations indicated the response of cultivars to fumonisin contamination to vary over localities/ seasons (r s =0.29 to 0.70). Cultivars DKC80-12B and LS8521B showed a degree of resistance to fumonisin contamination. Regression analysis yielded a significant relationship between HPLC data and qPCR, but not with the plating out of grain data suggesting the former to be a better indicator of potential fumonisin contamination. Site-specific, daily maximum temperature and rainfall data were provided by the ARC-Institute for Soil Water and Climate's meteorology office. No significant relationship between these weather parameters and colonization of grain by fumonisin producing Fusarium spp. was recorded, although a tendency was observed between fumonisin contamination and mean maximum temperature.

Mycotoxigenic Fusarium species associated with grain crops in South Africa – A review

“…28 The area under sorghum cultivation and the total production of sorghum in South Africa has been on a decline since 1986 ( Figure 1c). 2,16 While maize and wheat increased in yield per hectare (Figure 1a,b), the same was not observed for sorghum ( Figure 1c), for which the yield per hectare has remained mostly unchanged since 1995, fluctuating only with climatic changes. 2 This observation could be explained by the limited amount of research and development funds available to the sorghum industry, which is relatively small when compared to other major grain crops.…”

“…Whereas the total area harvested in South Africa has decreased from 4 118 000 ha in 1960 to 2 656 500 ha in 2014, yield has increased by 8 225 000 metric tons ( Figure 1a). 2,16 The increase in production has ensured that the importation of maize has been minimised, and any surplus can be exported (Figure 1a), thus contributing towards generating foreign currency. The Free State (43%), North West (20%) and Mpumalanga (19.5%) Provinces of South Africa were the main production areas during the 2013/2014 production season for total white and yellow maize harvested.…”

Preharvest Management Strategies and Their Impact on Mycotoxigenic Fungi and Associated Mycotoxins

“…Various countries have reported on the tolerance levels of maize and wheat cultivars to mycotoxigenic fungi and associated mycotoxins [65][66][67]. However, focus has been placed on the characterisation of inbred lines for the identification of appropriate breeding material towards resistance to mycotoxigenic fungi and their toxins [68][69][70][71][72][73][74].…”

Selecting lipopeptide‐producing, Fusarium‐suppressing Bacillus spp.: Metabolomic and genomic probing of Bacillus velezensis NWUMFkBS10.5

“…These diseases affect maize production in South Africa and other areas of the world (Boutigny et al, 2012(Boutigny et al, , 2011Summerell & Leslie, 2011). Maize, a staple crop in South Africa, is consumed daily in most households and used in the production of animal feeds (Janse van Rensburg, Mclaren, Flett, & Schoeman, 2015;Lamprecht, Tewoldemedhin, Botha, & Calitz, 2011); therefore, efforts to reduce loss due to preharvest and postharvest contamination by F. graminearum infection have recently gained significant attention (Boutigny et al, 2011;Mngqawa et al, 2016). The presence of mycotoxins zearalenone and deoxynivalenol found in maize grains infected by F. graminearum is also a cause for concern (Wang, Ndoye, Zhang, Li, & Liao, 2011).…”