RESUMO
Mycotoxin contaminated corn poses a risk to poultry production. Although mycotoxin regulatory guidelines are based on the hazards of individual mycotoxin contamination, feed and feed ingredients may be contaminated with multiple mycotoxins. The objective of this study was to assess mycotoxin co-contamination and its impact on the nutrient content of corn grain. Corn samples (n = 328) originating from various regions in the Southeastern U.S. were quantitatively analyzed for fumonisin (FUM), deoxynivalenol (DON), aflatoxin (AFB1) and zearalenone (ZEA) by HPLC-MS/MS. Nutritional content was analyzed by near-infrared spectroscopy, and color data were collected. All 328 samples were found to be contaminated with at least 1 mycotoxin: 100% contained FUM (19-24,680 µg/kg), 69.82% contained DON (0-9,640 µg/kg), 17.07% contained AFB1 (0-939 µg/kg), and 43.60% had detectable levels of ZEA (0-8,093.5 µg/kg). Most of the samples were contaminated with 2 or more mycotoxins, with only 18.29% of the samples containing a single mycotoxin. 38.41% of the samples had 2 mycotoxins present, 36.59 % had 3 mycotoxins, and 4.88% of the samples had all 4 tested mycotoxins present. Samples contaminated with AFB1 had significantly lower fat (P = 0.007) and lightness (P = 0.007); samples contaminated with DON had significantly higher starch (P < 0.001) and lower protein (P < 0.001). Samples contaminated with FUM had significantly higher protein (P = 0.008) and moisture (P = 0.019) and lower starch (P < 0.001). ZEA contaminated samples had significantly lower starch (P = 0.034). A correlation was observed between mycotoxin contamination and altered nutrient content in corn. This study provides further evidence that co-contamination of mycotoxins is the norm in corn, and that mycotoxin contamination correlates with impacts on the nutrient profile of feed corn.
RESUMO
Gummy stem blight (GSB) is a fungal disease affecting cucurbit crops, including watermelon (Citrullus lanatus), leading to significant yield losses. The disease is caused by three Stagonosporopsis species, of which Stagonosporopsis citrulli is the most common in the southeastern United States. Currently no gummy stem blight-resistant watermelon cultivars are available to growers. In this study, QTL-seq in an interspecific population developed from Sugar Baby × PI 189225 (Citrullus amarus) identified QTL on chromosomes 2, 5, 9 and 11. A novel QTL on chromosome 5 (Qgsb5.2) associated with resistance to S. citrulli (PVE = 13.3%) was confirmed by genetic mapping. KASP marker assays were developed for selection of Qgsb5.2 to allow breeders to track the allele contributing resistance to GSB, reducing the need for laborious phenotyping. Pyramiding different GSB resistance QTL could be a useful strategy to develop GSB resistant watermelon cultivars.