Browsing by Author "Mouton, Marili"

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    Resistance in South African maize inbred lines to the major ear rot diseases and associated mycotoxin contamination
    (Stellenbosch : Stellenbosch University, 2014-12) Mouton, Marili; Viljoen, Altus; Rose, Lindy J. ; Flett, B. C.; Stellenbosch University. Faculty of AgriSciences. Dept. of Plant Pathology.
    ENGLISH ABSTRACT: Maize (Zea mays L.) is one of the most important grain crops produced globally and serves as the primary source of carbohydrates and vitamins to millions of people in Africa. Whenever environmental conditions are favourable, fungal species such as Fusarium verticillioides, Fusarium graminearum sensu lato, Aspergillus flavus and Stenocarpella maydis frequently infect the ears of maize, reducing yield and grain quality. Of greater economic concern is the contamination of maize kernels with mycotoxins produced by ear rot pathogens due to its association with mycotoxicoses and immune suppression in humans and animals. Outbreaks of ear rot diseases commence in the field, but their associated toxins can be produced along the value chain. Planting resistant cultivars, as part of an integrated management strategy, could provide effective means of controlling preharvest ear rot diseases and mycotoxin accumulation in maize. Maize cultivars resistant to the major ear rot fungi and their mycotoxins are not yet available in South Africa and therefore should be developed in plant improvement programmes where durable resistance is combined with useful agronomic traits. The first step in introducing resistance into maize cultivars would be to find sources of genetic resistance. Infertility or unwanted traits may be present in wild relatives or other species of maize, and therefore locally adapted breeding material would be the most desirable source. This research aimed to identify publically available maize genotypes with durable resistance to the major ear rot pathogens and their associated mycotoxins in South Africa. In this study, a collection of inbred lines with diverse genetic backgrounds and valuable agronomic characteristics were evaluated under a range of field conditions. Some inbred lines were resistant to Fusarium ear rot (FER) and fumonisin contamination during artificially inoculated trials over two years. Furthermore, these FER-resistant inbred lines have been tested for resistance to other important maize ear rot diseases including Gibberella ear rot, Diplodia ear rot and Aspergillus ear rot in a multi-location field trial. Inbred lines with low and high levels of resistance to multiple infections were identified, but significant inbred x location interactions were observed. This suggests that potentially resistant lines will require further testing in an extra season to confirm their resistant status. If confirmed, these sources could be used to investigate the underlying mechanisms conferring resistance, or to develop molecular markers to facilitate the transfer of resistance into commercially valuable cultivars.