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Mycotoxins are naturally occurring toxic secondary metabolites produced by filamentous fungi contaminating various food and feed crops. Exposure to mycotoxins has been associated with mycotoxicosis, which accounts for a high percentage of diseases in developing countries where methods of food handling and storage are inadequate. For the first time, this study determined the diversity, prevalence and co-occurrence of mycotoxins across the beans value chain in Eswatini. A total of 226 beans samples received between 2001 and 2021 by mycotoxin laboratory at Malkerns research were analysed and more than 59.3% of the samples were found contaminated with mycotoxins. Results confirmed that aflatoxins (AFs) and Zearalenone (ZEN) were the main contaminating mycotoxins in beans. These mycotoxins occurred singly and co-occurred as mixtures in the samples analysed. Considerable differences regarding the prevalence of these mycotoxins were observed between samples from different beans value chain actors and between sampling years. Implications of the results on the pre and postharvest handling of beans in Eswatini and the health hazard that mycotoxins pose to humans and animals were discussed. The importance of clear and enforceable regulations on levels of mycotoxin in beans and other dietary products is emphasised and the need for research on the deleterious effects of mycotoxins and their metabolites on animal and human health is underlined.

Background: Sugarcane smut is a disease that is caused by the fungus Sporisorium scitamineum. This is a disease of economic importance in the sugarcane industry, because it can cause losses of up to 50%. Current management practices have shown to be ineffective in controlling the fungal disease and hence there is the need for the development of antifungal agents that are biocompatible, non-toxic, environmentally friendly and easy to develop. Biosynthesized silver nanoparticles have been found to possess antimicrobial properties, and have not been explored on S. scitamineum. Results: The synthesis of silver nanoparticles using Carissa spinarum yielded particles that were spherical, smooth and they had a size range from 3nm to 33nm in size. Optimization of the mixtures using ultraviolet-visual spectroscopy (UV-Vis) showed peaks in the range of 340nm to 450nm. The Fourier transform infrared spectroscopy analysis identified proteins to be essential capping agents and reducing sugars were responsible for the reduction of the silver nitrate to nanoparticles and stabilizing the nanoparticles. The biosynthesized silver nanoparticles had the highest antifungal activity at 5mg/ml, while the minimum inhibitory concentration and minimum fungal concentration were 78µg/ml. The in-vivo assays showed a significant (at P=0.05) reduction of the pathogen biomass concentration on the plants that were treated with the nanoparticles when compared to the control plants. The application of 58.5µg/ml of the b-AgNPs to the S. scitamineum resulted to a significant (P=0.05) increase in expression of the bE and bW genes, while the treatment with 39 µg/ml significantly (P=0.05) increased the expression of the bE gene, but had no significant (P=0.05) change in the expression of the bW gene. Conclusion: Silver nanoparticles that were synthesized successfully using C. spinarum crude extract inhibited the growth of S. scitamineum both in-vitro and in-vivo. The silver nanoparticles had a regulatory effect on the expression of the bE and bW genes in the fungus.

Background: Sugarcane smut, caused by Sporisorium scitamineum, is a disease of economic importance in the sugarcane industry, occasioning losses of up to 50%. Current management practices have been shown to be ineffective in controlling the fungal disease and hence the understanding of the local pathogen and development of appropriate control measures is required. This study investigates the morphology, development patterns and molecular variability of Sporisorium scitamineum isolates in Eswatini to understand its pathogenicity for effective control.Results: Fungal isolates were collected along the Sugarbelt in Lowveld of Eswatini. The isolates were verified by polymerase chain reaction (PCR) using the bE 4 and bE 8 specific primers with an amplification of a 420bp fragment; this was further verified by the sequencing results. The teliospores from the isolates were uniform for the brown colour, spiny texture and circular shape. The teliospore sizes were significantly (P=0.05) different among the isolates. The isolate from Big-Bend had a mean diameter of 5.55µm, while Simunye, Nsoko and Mhlume had average diameters of 4.69µm, 4.98µm and 4.87µm, respectively. The documentation of the developmental stages revealed that the samples were of variable virulence with significantly (P=0.05) different rates of promycelium development. Genetic distance matrix analysis and the cluster analysis showed a high homology (99-100%) among the local isolates.Conclusion: There is very low variability in the strains that are found in the selected sugarcane growing areas in Eswatini. Local isolates may possess varying virulence levels, but may not require variable management strategies.