Incidence of Potentially Toxigenic Fungi and Aflatoxin in Maize (Zea mays L.) Infected by Maize Lethal Necrosis Disease in Bomet, Narok, and Nakuru Counties of Kenya

Abstract

Maize Lethal Necrosis Disease (MLND) is one of the most important biotic factors limiting maize productivity. MLND is believed to increase concomitant fungal infections that cause food poisoning in humans and livestock. This study aimed to establish the relationship between MLND and the associated fungal infections. Fifty four maize grain samples were obtained from three experimental sites in Bomet, Narok and Nakuru Counties during the maize growing seasons of 2019. A complete randomized experimental design with three replicates was applied using six hybrid maize varieties classified as resistant, tolerant and susceptible to MLND. The resistant varieties were KATEH16-02-R and DK777, tolerant (WE5135and WE5140), and the susceptible varieties (DUMA 43 and PH30G-20).Fungal colonies were isolated on Potato Dextrose Agar (PDA) medium amended with 25μg/l of streptomycin and tetracycline. Characterization of the fungal species was based on morphological and microscopic characterization. A total of 1861 fungal isolates were recovered from the samples, representing 82.25% Fusarium verticilliodes, 15.80% of Penicillium species 1.44% of Aspergillus flavus, 0.48% of Aspergillus niger and 0.2% of Aspergillus parasiticus. Fusarium was the most predominant fungi in all three study sites, with a mean relative density of 86%. Using Enzyme Linked Immunorbent Assay (ELIZA) method, Aflatoxin concentration levels of between 0.3 and 2.8 μg/kg were detected in 38.89 % of the samples. A significant positive correlation was established between MLND and aflatoxin levels (r=0.7441, p<0.001). These findings provide critical information on concomitant fungal species infection in maize infected with MLND and the potential risk of aflatoxins. Therefore there is a need to create awareness to the public about the detrimental effects of consuming MLND infected maize by both human and animals.