MRC PhD students

Title: Fumonisin regulatory genes in Fusarium verticillioides and other fumonisin-producing fungi

Investigator: Lorraine Moses, PROMEC Unit

Supervisors: Prof. Brenda Wingfield (Dept of Genetics, FABI, University of Pretoria), Dr Hester Vismer (PROMEC Unit, MRC), Prof. Walter Marasas

Fumonisins have been associated with the development of oesophageal cancer, and are also considered a potential risk factor for neural tube defects. Factors that influence mycotoxin production by Fusarium verticillioides under natural and experimental conditions are being investigated.

Cultural mutation has often been found to occur when F. verticillioides is grown on media rich in carbohydrates and these mutations may involve loss of virulence and the ability to produce toxins. In order to elucidate the mechanism by which F. verticillioides produces fumonisins, a study into the gene regulation of fumonisin production is being conducted. 

Phylogenetic analyses were performed on a population of F. verticillioides strains as well as other fumonisin-producing Fusarium species of Section Liseola, to determine the genetic diversity and genetic relatedness of strains that exhibited various fumonisin profiles. This method is also used to aid in species identification. The purpose of this study is to elucidate whether the AFLP genotype corresponds with the fumonisin producing ability phenotype of strains. Application of this method has the potential to identify toxigenic species and replace the conventional methods that are currently labour intensive and time-consuming tasks. Application of such methods will have far reaching implications in industry and the prediction of fumonisin levels that may be produced in contaminated maize.

The genetic diversity of F. globosum isolates, also fumonisin producers, was determined in order to resolve the means of reproduction, as low diversity will be an indication of clonal (asexual) reproduction, and high diversity will be an indication of sexual reproduction. It is important to determine mode of reproduction, as meiotic recombination could result in the diversity of genes that govern traits involved in pathogenesis and toxin production.