|Del Ponte, E|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/25/2013
Publication Date: 10/25/2013
Citation: Spolti, P., Kuhnem, P.R., Ward, T.J., Del Ponte, E.M. 2013. Survey and competition assay data suggest species-specific difference in host/niche adaptation influence the distribution of Fusarium graminearum species complex pathogens in Brazil. Meeting Abstract. Interpretive Summary:
Technical Abstract: The Fusarium graminearum species complex (FGSC) comprises at least 16 toxigenic species of economic concern to cereal crops. In Brazil, six species of the FGSC have been identified, but their frequencies vary according to the host species. Although F. graminearum (Fgra) is dominant in wheat (>90%) and F. meridionale (Fmer) is dominant in maize (>65%), both of these species and F. cortaderiae (Fcor) occur in these two crops. In 2011, we conducted intensive sampling of FGSC isolates at three non-tilled wheat fields, 174 to 275 km apart, in Rio Grande do Sul, Brazil. In addition, FGSC isolates were collected from corn stubble (perithecial isolations) prior to flowering and from harvested diseased wheat kernels. Sixty “saprophytic” and 100 “pathogenic” isolates were identified to species/trichothecene genotype through a multilocus genotyping (MLGT) assay. From the corn stubble, Fmer was dominant (70%), followed by Fgra (16,7%) and Fcor (13,3%). From wheat kernels, Fgra was dominant (85%), followed by Fcor (10%) and Fmer (5%). Fgra isolates were all of the 15-ADON genotype, Fmer were of the NIV genotype, and Fcor were mostly of the NIV genotype with a few Fcor of the 3-ADON genotype (n=4). In the greenhouse, flowering spikes of three wheat cultivars were spray-inoculated with a mixed spore suspension (1:1, Fgss:Fmer). Thirty-six (12/cv.) isolates from diseased kernels were paired to the inoculated isolates in a mycelia compatibility assay. Fgra was the most common species recovered from diseased kernels (86% to 100%). It is hypothesized that Fgra populations are better adapted and more pathogenic toward wheat, whereas Fmer is better adapted to saprophytic survival on maize stubble and possibly more pathogenic to maize.