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Determining resistance to Fusarium verticillioides and fumonisin accumulation in African maize inbred lines resistant to Aspergillus flavus and aflatoxins

Rose, LindyJoy, Okoth, Sheila, Beukes, Ilze, Ouko, Abigael, Mouton, Marili, Flett, BradleyCharles, Makumbi, Dan, Viljoen, Altus
Euphytica 2017 v.213 no.4 pp. 93
Aspergillus flavus, DNA, Fusarium verticillioides, Zea mays, aflatoxins, corn, disease resistance, ear rot, field experimentation, fumonisins, fungi, genotype-environment interaction, grain yield, inbred lines, liquid chromatography, mycotoxicosis, pathogens, plant breeding, quantitative polymerase chain reaction, resistance mechanisms, tandem mass spectrometry, Kenya, South Africa
Fusarium verticillioides and Aspergillus flavus cause Fusarium ear rot (FER) and Aspergillus ear rot (AER) of maize, respectively. Both pathogens are of concern to producers as they reduce grain yield and affect quality. F. verticillioides and A. flavus also contaminate maize grain with the mycotoxins fumonisins and aflatoxins, respectively, which has been associated with mycotoxicosis in humans and animals. The occurrence of common resistance mechanisms to FER and AER has been reported. Hence, ten Kenyan inbred lines resistant to AER and aflatoxin accumulation were evaluated for resistance to FER, F. verticillioides colonisation and fumonisin accumulation; and compared to nine South African lines resistant to FER and fumonisin accumulation. Field trials were conducted at three localities in South Africa and two localities in Kenya. FER severity was determined by visual assessment, while F. verticillioides colonisation and fumonisin content were quantified by real-time PCR and liquid chromatography tandem mass spectrometry, respectively. Significant genotype x environment interactions was determined at each location (P ≤ 0.05). Kenyan inbred CML495 was most resistant to FER and F. verticillioides colonisation, and accumulated the lowest concentration of fumonisins across localities. It was, however, not significantly more resistant than Kenyan lines CML264 and CKL05015, and the South African line RO549 W, which also exhibited low FER severity (≤5%), fungal target DNA (≤0.025 ng μL⁻¹) and fumonisin levels (≤2.5 mg kg⁻¹). Inbred lines resistant to AER and aflatoxin accumulation appear to be promising sources of resistance to F. verticillioides and fumonisin contamination.