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Fusarium head blight (FHB) is a disease problem (primarily caused by Fusarium graminearum Schwabe) that affects the quality and yield of barley (Hordeum vulgare L.) grain. The objectives of this study were to identify the location of quantitative trait loci (QTL) for resistance to FHB in a two-rowed by six-rowed population, to examine the association of FHB resistance with heading date and the Vrs1 (two-rowed spike morphology) locus, to validate the location of the major FHB resistance QTL primarily detected in the field, and to identify simple sequence repeat (SSR) markers linked to the QTL for FHB resistance. We created a genetic map of 143 molcular markers from a population derived from the parents Fredrickson (two-rowed, moderately resistant) and Stander (six-rowed, susceptible). The Fredrickson/Stander population was evaluated in two field environments by a grain spawn inoculation method, two field environments by a spray inoculation, and two greenhouse environments. QTL analysis detected three distinct regions on chromosome 2(2H) associated with FHB resistance; two of these regions were also associated with resistance to deoxynivalenol (DON) accumulation. One FHB resistance QTL was also associated with heading date, while another FHB resistance QTL was found associated with the Vrs1 locus. The third FHB resistance QTL was detected only in the greenhouse, but was coincident with a QTL for resistance to DON accumulation in the field. All three QTL were detected in the greenhouse, indicating that this environment may be useful for selecting FHB resistant barley genotypes. SSR markers were identified that are linked with each QTL and could prove useful for marker-assisted trait manipulation. Finally, the two major QTL detected in the field were validated using an independent population with Fredrickson and Stander parents. [ABSTRACT FROM AUTHOR]

Focuses on the registration of Lacey, a spring barley. Development of barley by Minnesota Agricultural Experiment Station; Purpose of development; Application of pedigree method with single-seed descent; Replacement of Robust varieties; Quality of the barley; Comparison between Lacey and Robust.

One of the major concerns with Fusarium head blight (FHB) of barley is the potential health risks to livestock and humans through the accumulation of the mycotoxin deoxynivalenol (DON) in infected grain. To define the role of the host in DON accumulation during the early stages of disease development, we conducted a series of greenhouse experiments. We inoculated single spikelets of greenhouse-grown plants with Fusarium graminearum, moved the plants to a dew chamber, and harvested the inoculated spikelets after 72 h for DON analysis. We conducted a quantitative trait locus (QTL) analysis using a genetic mapping population, constructed with the parents Stander and Frederickson, that segregated for DON accumulation after single-spikelet inoculation in two experiments. A single QTL on chromosome 3 explained 18 and 35% of the phenotypic variation in the two experiments. To validate this QTL for DON accumulation, we used a DNA marker to select near-isogenic lines from a family from the mapping population that was segregating at this QTL. Disease symptom development was similar between the nearisogenic lines; however, the mean DON concentration of the lines homozygous for the allele from the high DON parent was 2.5-fold more than the lines homozygous for the alternate allele. A time course experiment showed that this effect on toxin accumulation was observed at 10 days post inoculation. The near-isogenic lines developed in this study should prove useful for further exploration of the role of DON in FHB. [ABSTRACT FROM AUTHOR]