On the fungal contamination dynamics in maize: towards competitive exclusion to control mycotoxins

Samenvatting

Fungi are ubiquitous in nature and infect various crops. I investigated the spectrum of fungi infecting preharvest maize in the field in relation to different rainfall patterns. Sarocladium and Fusarium were the most dominant fungi. Higher levels of Sarocladium resonated with lower levels of both Fusarium and its carcinogenic metabolite fumonisin-B1 in maize. Furthermore, I investigated the diversity of Aspergillus section Flavi (Flavi) some of whose fungal species are known to produce carcinogenic aflatoxins contaminating crops. In laboratory studies, antioxidant (selenium) promoted better sporulation of the atoxigenic (non-aflatoxin-producing) Flavi than toxigenic (aflatoxin-producing) counterparts, and prevented spikes in aflatoxin.

Overall, findings lay down two prospects for preharvest maize: 1) prevention of proliferation of Fusarium by non-pathogenic strains of Sarocladium for the combat of fumonisins. 2) prevention of aflatoxin spikes in maize by antioxidant, while simultaneously promoting a competitive growth advantage of atoxigenic Flavi over toxigenic counterparts for the control of aflatoxin.