CONICET | Buscador de Institutos y Recursos Humanos

Current maize hybrids hold some levels of broad-based resistance to ear infections by Fusarium. However, when severe outbreaks occur, mycotoxin contamination still may occur in some hybrids and research is being conducted to facilitate development of more resistant plant genotypes. Several new sources of resistance were identified and introgressed into breeding populations for selection. Pedigree selection, broadly used for inbred development, is more effective in later generations when genotypic variances reach maximum values. This is consistent with the hypothesis of disease resistance based on several genes with additive effects. Thus, genes mapping should be also conducted in later generations. Minor isolate-by-hybrid interaction effects were observed even for isolates belonging to different Fusarium spp. Inbred selection after inoculation of a low fumonisin producer isolate (F. proliferatum) was effective to develop F1 hybrids resistant to ear rots and mycotoxin contamination caused by several Fusarium spp. (F. proliferatum, F. verticillioides, and F. graminearum). While resistance to F. verticillioides accounted for most of the genotypic variability for resistance to grain fumonisin accumulation, specific genes seem to affect DON accumulation, after inoculation with F. graminearum, and additional genetic progress should be achieved by including DON as selection parameter. Information on disease resistance components might also facilitate resistant hybrid development. Several mechanisms were already characterized including the presence of yet not identified volatile compounds in grain capable to induce and/or significantly promote in vitro Fusarium growth depending on maize genotype.

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