Diversity in Mycotoxins and fungal species infecting wheat in Nakuru District, Kenya
Wagacha, John Maina
MetadataShow full item record
Mycotoxin contamination of wheat kernels and diversity of fungal pathogens were monitored in a survey of 26 fields in Nakuru district, Kenya, in 2006. Sampling was performed twice; at mid-anthesis in July for leaves, stems and spikelets and at harvest in September for spikelets and kernels. Kernels were analysed for the occurrence of 32 mycotoxins using a high performance liquid chromatography – electrospray tandem mass spectrometry (LC-ESI-MS/MS) method. Fungi were isolated from surface-sterilized tissues and differentiated morphologically to the genus level. Fusarium isolates were identified based on the sequence of translation elongation factor 1-alpha gene. Eleven Fusarium-related mycotoxins were quantified with deoxynivalenol being detected at highest frequency (69%) and highest concentrations. Occurrence of enniatins in wheat (50%) is reported for the first time in Kenya. Non-Fusarium mycotoxins detected included aflatoxin G2, ochratoxin A, alternariol and alternariol monomethyl ether. Prevalence of Fusarium species on different wheat parts was 100% at both growth stages. Nineteen Fusarium species were identified with seven species –Fusarium chlamydosporum, Fusarium boothi, Fusarium poae, Fusarium scirpi, Fusarium arthrosporioides, Fusarium oxysporum and Fusarium graminearum– accounting for 80% of infections. At anthesis, spikelets and leaves were the most and least susceptible tissue, respectively. At harvest, infection of spikelets was 59% higher than that of kernels.