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A quantitative PCR method for determining relative infection rates of maize callus by Fusarium graminearum in screening for fungal resistance genes

Eric Johnson: USDA/ARS/NCAUR

<div>Maize grown in the United States is susceptible to contamination by ear mold fungi. Some of these fungi can produce mycotoxins that are harmful to animals and humans. It is important to identify novel ways of reducing maize ear mold contamination. Some genetic studies of maize over the years have identified quantitative trait loci that contribute to resisting mold contamination. The gene(s) at these loci need to be individually tested in the laboratory to confirm their suspected role in fungal resistance. We developed a laboratory method using quantitative PCR to accurately quantify the amount of <em>Fusarium graminearum</em> in maize callus. This PCR method can detect the fungus 12 hours after placement on the callus. We found that callus expressing a known fungal resistance gene contained much less fungus than callus expressing a gene not expected to contribute to fungal resistance. This methodology using callus can test putative fungal resistance genes more quickly than methods utilizing transgenic plants, which are more costly to produce and maintain. This novel method for evaluating maize genes for resistance against <em>F. graminearum</em> holds promise for accelerating the development of new lines that are safer for ingestion by livestock and humans.</div>