Impact of aggressiveness of Fusarium graminearum and F. culmorum isolates on yield parameters and mycotoxin production in wheat

Abstract

Plant-associated isolates from Fusarium graminearum and F. culmorum were inoculated on wheat in field experiments in 2007 and 2008 to ascertain their influence on fungal colonization of the ears, as well as mycotoxin contamination (deoxynivalenol, DON; nivalenol, NIV; zearalenone, ZEA) and yield parameters in the mature crop after inoculation with or without irrigation. The isolates were assigned to four different groups of aggressiveness on the basis of pathogenic symptom development and mycotoxin production in vitro. Increased levels of trichothecene-producing Fusarium DNA in the ears indicated a successful inoculation of the plants, which resulted in increased DON content in the wheat kernels in 2007. Dry conditions at anthesis markedly suppressed fungal colonization as well as mycotoxin accumulation. However, due to precipitation during the ripening period, yield and thousand-kernel weight were similar whether or not irrigation was applied at the time of inoculation. The level of aggressiveness among the isolates as determined in vitro was not reflected in the field experiment. The activity of the extracellular invertase in developing ears increased as a plant response to pathogen infection, especially when the plants were irrigated at the time of inoculation. In 2008, the Fusarium inoculation of wheat heads did not cause fungal growth and mycotoxin contamination in the grain, because of the dry weather conditions that occurred over the entire period of anthesis and ripening. The risk of future mycotoxin contamination in grains was discussed based on climate change prognosis.

Cocultivation of phytopathogenic Fusarium and Alternaria strains affects fungal growth and mycotoxin production

“…Fusarium culmorum and F. graminearum as well as A. tenuissima used in the present study were aggressive colonizers of wheat ears and well known producers of mycotoxins in grains (Korn et al . ). Under natural field conditions, the ripening grain ears are colonized by several saprophytic and pathogenic fungi (Dawood ; D'Mello et al .…”

“…; Korn et al . ), probably based on enzyme activities, ascospore production and metabolite profiling. However, to our knowledge, similar enhancement of fungal growth in cocultures has never been described before in the literature.…”

“…These four isolates were selected for this study because of the fact that they are proven high mycotoxin producers with a pronounced aggressive potential screened in a biotest (Holz ; Korn et al . ).…”

“…Macroconidia were harvested as described previously (Korn et al . ). The spore suspension was adjusted to a density of 2 × 10 5 conidia ml −1 .…”

Antagonistic interactions between Aureobasidium pullulans and Fusarium culmorum, a fungal pathogen of winter wheat

“…In a field study by Schade-Schütze et al (2000), inoculation of wheat spikes with F. culmorum reduced 1000 kernel weight by 14-61 %. Korn et al (2011) demonstrated that the F. culmorum isolate was characterized by higher aggressiveness in wheat heads than F. graminearum isolates, and that its aggressiveness only partially resulted from the production of mycotoxins such as deoxynivalenol, nivalenol and zearalenone. In our study, higher grain filling rates were noted for winter wheat spikes non-inoculated with F. culmorum and protected with A. pullulans, compared with untreated spikes.…”