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Previous studies have shown that there is considerable population structure in cultivated barley (Hordeum vulgare Lo), with the strongest structure corresponding to differences in row number and growth habit. U.S. barley breeding programs include six-row and two-row types and winter and spring types in all combinations. To facilitate mapping of complex traits in breeding germplasm, 1816 barley lines from 10 U.S. breeding programs were scored with 1536 single nucleotide polymorphism (SNP) genotyping assays. The number of SNPs segregating within breeding programs varied from 854 to 1398. Model-based analysis of population structure showed the expected clustering by row type and growth habit; however, there was additional structure, some of which corresponded to the breeding programs. The model that fit the data best had seven populations: three two-row spring, two six-row spring, and two six-row winter. Average linkage disequilibrium (LD) within populations decayed over a distance of 20 to 30 cM, but some populations showed long-range LD suggestive of admixture. Genetic distance (allele-sharing) between populations varied from 0.11 (six-row spring vs. six-row spring) to 0.45 (two-row spring vs. six-row spring). Analyses of pairwise LD revealed that the phase of allelic associations was not well correlated between populations, particularly when their allele-sharing distance was >0.2. These results suggest that pooling divergent barley populations for purposes of association mapping may be inadvisable. doi: 10.2135/cropsci2009.04.0198

Abstract Background The trichothecene mycotoxin deoxynivalenol (DON) may be concentrated in distillers dried grains with solubles (DDGS; a co-product of fuel ethanol fermentation) when grain containing DON is used to produce fuel ethanol. Even low levels of DON (≤ 5 ppm) in DDGS sold as feed pose a significant threat to the health of monogastric animals. New and improved strategies to reduce DON in DDGS need to be developed and implemented to address this problem. Enzymes known as trichothecene 3-O-acetyltransferases convert DON to 3-acetyldeoxynivalenol (3ADON), and may reduce its toxicity in plants and animals. Results Two Fusarium trichothecene 3-O-acetyltransferases (FgTRI101 and FfTRI201) were cloned and expressed in yeast (Saccharomyces cerevisiae) during a series of small-scale ethanol fermentations using barley (Hordeum vulgare). DON was concentrated 1.6 to 8.2 times in DDGS compared with the starting ground grain. During the fermentation process, FgTRI101 converted 9.2% to 55.3% of the DON to 3ADON, resulting in DDGS with reductions in DON and increases in 3ADON in the Virginia winter barley cultivars Eve, Thoroughbred and Price, and the experimental line VA06H-25. Analysis of barley mashes prepared from the barley line VA04B-125 showed that yeast expressing FfTRI201 were more effective at acetylating DON than those expressing FgTRI101; DON conversion for FfTRI201 ranged from 26.1% to 28.3%, whereas DON conversion for FgTRI101 ranged from 18.3% to 21.8% in VA04B-125 mashes. Ethanol yields were highest with the industrial yeast strain Ethanol Red®, which also consumed galactose when present in the mash. Conclusions This study demonstrates the potential of using yeast expressing a trichothecene 3-O-acetyltransferase to modify DON during commercial fuel ethanol fermentation.

Many quantitative trait loci (QTL) in wheat (Triticum aestivum L.) conferring resistance to Fusarium head blight (FHB), caused by the Fusarium graminearium, have been mapped in diverse genetic sources. Use of nonadapted FHB resistant sources by breeding programs In the soft red winter (SRW) wheat region of the United States has not been very successful. Therefore, native sources of FHB resistance identified or validated in SRW wheat cultivars predominantly have been used. The breeding line VA00W-38 has moderate FHB resistance and does not possess any previously identified exotic sources of resistance in its parentage. A set of 182 recombinant inbred lines (RILs) were developed from the cross VA00W-38 × Pioneer brand '26R46' and tested in field scab nurseries and natural conditions in two environments for each of 2 yr. Eight consistent QTL were identified on chromosomes 1BL, 2A, 2DL, 5B, 6A, and 7A and explained 6.5 to 21.3% of phenotypic variation of traits associated with FHB resistance. Their logarithm of odds (LOD) scores ranged from 2.5 to 6.7. Favorable alleles to decrease FHB are from VA00W-38 except one QTL on chromosome 7A. Major QTL on chromosomes 2DL, 6A, and 5B decreased FHB index (IND), Fusarium damaged kernels (FDK), and deoxynivalenol (DON), respectively. Tightly linked markers identified for these consistent QTL can be used to select for favorable alleles associated with FHB resistance in breeding populations after validation in diverse genetic backgrounds. [ABSTRACT FROM AUTHOR]