title: Evaluating three commonly used growth media for assessing fumonisin analogues FB1,FB2and FB3production by nine Fusarium verticillioides isolates.
abstract: Maize is most often infected by the fumonisin-producing Fusarium verticillioides. Total fumonisins of natural infected grain is made up of FB1, FB2and FB3with FB1occurring naturally at higher levels. A maize plant can be infected with more than one F. verticillioides isolate, and finding a reliable method to elucidate the toxigenic potential of these isolates is important to extrapolate the possible fumonisin risk to consumers of grain. It is not clear whether F. verticillioides produces similar fumonisin levels, as well as fumonisin analogue ratios, across media. In this study, nine F. verticillioides isolates were subjected to three methods of fumonisin testing using liquid media, maize patties and a field trial (silk inoculation of grain) in Potchefstroom, South Africa. Spore concentrations of 1 × 106conidia ml-1of each isolate were used to inoculate the different media and levels fumonisin analogues were measured using HPLC. Fumonisin production per isolate was highly variable and was influenced by the two-way interaction of F. verticillioides isolate × growth media. Total fumonisins produced in the liquid medium ranged from 0 to 21.3 ppm, on maize patties fumonisins they ranged from 0 to 21.5 ppm, and in the silk inoculation technique they ranged from 0 to 15.5 ppm. The fumonisin analogue FB1occurred at higher levels followed by FB3in both in vitro studies. In the silk inoculation technique, fumonisin analogue FB2was the second highest occurring analogue after FB1. Isolate GCI 282 produced higher FB2and FB3levels than FB1in the patties and grain, respectively. In order not to miscalculate the fumonisin and analogue ratio levels per F. verticillioides isolate, the growth medium will have to be optimised for each isolate and more than one growth medium used.
authors.affiliation: a Agricultural Research Council-Grain Crops Institute , Potchefstroom , South Africa.
authors.forename: A
authors.initials: A
authors.lastname: Schoeman
authors.affiliation: a Agricultural Research Council-Grain Crops Institute , Potchefstroom , South Africa.|b Unit for Environmental Sciences and Management, Faculty of Natural Sciences , North-West University , Potchefstroom , South Africa.
authors.forename: B C
authors.initials: BC
authors.lastname: Flett
authors.affiliation: a Agricultural Research Council-Grain Crops Institute , Potchefstroom , South Africa.
authors.forename: B
authors.initials: B
authors.lastname: Janse van Rensburg
mesh_terms: D003470:Culture Media / Q000494:pharmacology*; D037341:Fumonisins / Q000032:analysis / Q000378:metabolism*; D005670:Fusarium / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D003470:Culture Media; D037341:Fumonisins
keywords: Fusarium verticillioides; fumonisin analogue; fumonisins; liquid media; maize patties; silk inoculation