C. A. Griffey

Effectiveness of adult-plant resistance in reducing grain yield loss to powdery mildew in winter wheat.

We studied the effectiveness of adult-plant resistance (APR) in protecting grain yields in winter wheat grown in Virginia under varying levels of intensity of powdery mildew (caused by Blumeria graminis f. sp. tritici) obtained with different fungicide treatments in field experiments in two crop years. Mildew severity was assessed at three to four plant growth stages, and the data were used to calculate mean mildew severity (MMS) and area under the mildew disease progress curve. The susceptible cultivar Saluda had an average MMS of 5.3%. MMS and grain yield for Saluda were significantly negatively correlated in both years, and yield loss averaged 13.4% in untreated plots relative to full-season control plots (.)

Yield losses in winter barley resulting from a new race of Puccinia hordei in North America

Leaf rust resistance, derived from the barley cultivar Cebada Capa, has been effective in the southeastern United States since 1950, when it was first used in the Virginia barley breeding program. In 1990, races of Puccinia hordei virulent to barleys that possess the resistance gene Rph7 were identified for the first time in North America. This research assessed the potential impact of Rph7-virulent races of leaf rust on grain yield and quality in winter barley. Natural epidemics of leaf rust occurred in cultivar trials at Painter and Warsaw, Virginia, in 1991 and 1992. Mean leaf rust severities for barley lines observed over three environments ranged from 10% for the moderately resistant line VA 90-42-45 to 76% for the susceptible cultivar Barsoy

Pathotypes of Puccinia hordei with virulence for the barley leaf rust resistance gene Rph7 in the United States.

The barley (Hordeum vulgare) accession Cebada Capa has been used extensively as a source of resistance to the leaf rust pathogen (Puccinia hordei) in the Virginia barley breeding program, Cebada Capa possesses the resistance gene Rph7; and in the mid-Atlantic region of the United States, cultivars derived from it have remained resistant to P. hordei since 1968. In 1990, outbreaks of leaf rust were observed in Virginia on cultivars carrying Rph7. Isolates of P. hordei collected from these cultivars were found to possess virulence on Cebada Capa in greenhouse and growth chamber experiments. In addition to Virginia, P. hordei isolates with Rph7 virulence were identified in Pennsylvania and California

Confirmation of Three Quantitative Trait Loci Conferring Adult Plant Resistance to Powdery Mildew in Two Winter Wheat Populations

Hypersensitive, race specific genes primarily have been deployed to control powdery mildew (Blumeria graminis (DC) EO Speer f. sp. tritici) in wheat (Triticum aestivum L.); however, recent efforts have shifted to breeding for more durable resistance. Previously, three quantitative trait loci (QTL) for adult plant resistance (APR) to powdery mildew in the winter wheat cultivar Massey were identified in a Becker/Massey (BM) F2:3 population. Fourteen new simple sequence repeat (SSR) markers were added to the pre-existing BM F2:3 linkage maps near the QTL for APR on chromosomes 1BL (QPm.vt-1BL), 2AL (QPm.vt-2AL), and 2BL (QPm.vt-2BL). Genetic linkage maps comprised of 17 previously and newly mapped SSRs from the BM population on chromosomes 1BL, 2AL, and 2BL were constructed in a USG 3209/Jaypee (UJ) F6:7 recombinant inbred line (RIL) confirmation population, wherein the APR resistance of USG 3209 was derived from Massey. Interval mapping analysis of mildew severity data collected in 2002 (F5:6) and 2003 (F6:7) field experiments with marker genotypic data obtained in 2003 (F6:7) confirmed the presence of the three QTL governing APR to powdery mildew in the UJ RILs. The QTL QPm.vt-1BL, QPm.vt-2AL, and QPm.vt-2BL explained 12–13, 59–69, and 22–48% of the phenotypic variance for powdery mildew severity in the UJ confirmation populations, respectively, in two field experiments. The current study verified that the elite wheat cultivar USG 3209 possesses the same QTL for APR as its parent Massey.

Near-Infrared Analysis of Ground Barley for Use as a Feedstock for Fuel Ethanol Production

The objective of this study was to explore the potential of near-infrared spectroscopy for determining the compositional quality properties of barley as a feedstock for fuel ethanol production and to compare the prediction accuracy between calibration models obtained using a Fourier transform near-infrared system (FT-NIR) and a dispersive near-infrared system. The total sample set contained 206 samples of three types of barley, hull-less, malt, and hulled varieties, which were grown at various locations in the eastern U.S. from 2002 to 2005 years. A new hull-less barley variety, Doyce, which was specially bred for potential use in ethanol production, was included in the sample set. One hundred and thirty-eight barley samples were used for calibration and sixty-eight were used for validation. Ground barley samples were scanned on both a FT-NIR spectrometer (10000 to 4000 cm−1 at 4 cm−1 resolution) and a dispersive NIR spectrometer (400 to 2498 nm at 10 nm resolution), respectively. Six grain components, moisture, starch, β-glucan, protein, oil, and ash content, were analyzed as parameters of barley quality. Principal component analysis showed that barley samples could be classified by their types: hull-less, malt, and hulled. Partial least squares regression indicated that both FT-NIR and dispersive NIR spectroscopy have the potential to determine quality properties of barley with an acceptable accuracy, except for β-glucan content. There was no predictive advantage in using a high-resolution FT-NIR instrument over a dispersive system for most components of barley.

Evaluation of Components of Fusarium Head Blight Resistance in Soft Red Winter Wheat Germ Plasm Using a Detached Leaf Assay

A large environmental influence on phenotypic estimates of disease resistance and the complex polygenic nature of Fusarium head blight (FHB) resistance in wheat (Triticum aestivum) are impediments to developing resistant cultivars. The objective of this research was to investigate the utility of a detached leaf assay, inoculated using inoculum from isolates of Microdochium nivale var. majus, to identify components of FHB resistance among 30 entries of U.S. soft red winter wheat in the 2002 Uniform Southern FHB Nursery (USFHBN). Whole plant FHB resistance of the USFHBN entries was evaluated in replicated, mist-irrigated field trials at 10 locations in eight states during the 2001-2002 season. Incubation period (days from inoculation to the first appearance of a dull gray-green water-soaked lesion) was the only detached leaf variable significantly correlated across all FHB resistance parameters accounting for 45% of the variation in FHB incidence, 27% of FHB severity, 30% of Fusarium damaged kernels, and 26% of the variation in grain deoxynivalenol (DON) concentration. The results for incubation period contrasted with previous studies of moderately resistant European cultivars, in that longer incubation period was correlated with greater FHB susceptibility, but agreed with previous findings for the Chinese cultivar Sumai 3 and CIMMYT germ plasm containing diverse sources of FHB resistance. The results support the view that the detached leaf assay method has potential for use to distinguish between specific sources of FHB resistance when combined with data on FHB reaction and pedigree information. For example, entry 28, a di-haploid line from the cross between the moderately resistant U.S. cultivar Roane and the resistant Chinese line W14, exhibited detached leaf parameters that suggested a combination of both sources of FHB resistance. The USFHBN represents the combination of adapted and exotic germ plasm, but four moderately resistant U.S. commercial cultivars (Roane, McCormick, NC-Neuse, and Pat) had long incubation and latent periods and short lesion lengths in the detached leaf assay as observed in moderately FHB resistant European cultivars. The dichotomy in the relationship between incubation period and FHB resistance indicates that this may need to be considered to effectively combine exotic and existing/adapted sources of FHB resistance.

Comparative Effects of 1BL/1RS Translocation in Relation to Protein Composition and Milling and Baking Quality of Soft Red Winter Wheat

ABSTRACT Forty grain samples, derived from six soft red winter wheat lines with 1BL/1RS and four genotypes without the translocation, grown in four diverse environments, were used to assess test weight, flour yield, protein content of grain and flour, rheological properties, and end-use characteristics in cakes and cookies. Wheat lines with 1BL/1RS had similar or higher mean test weights than lines without the translocation. Mean flour yields were similar for the two groups. Test weight was not predictive of flour yield. Mean values for grain moisture, grain protein, and rheological properties, as measured by farinograph for mixing time stability and mixing tolerance index, were similar for wheat lines with and without 1BL/1RS. In several cases, flour from lines with 1BL/1RS produced dough with greater mixing tolerance and cakes with higher volume and softer texture than did check lines without the translocation. However, the translocation in these soft red winter wheat lines resulted in higher farinograp...

Genes governing resistance to Puccinia hordei in thirteen spring barley accessions

ABSTRACT Leaf rust, caused by Puccinia hordei, is an important disease of barley in many parts of the world. In the eastern United States, this disease was effectively controlled for over 20 years through the deployment of cultivars carrying the resistance gene Rph7. Isolates of P. hordei with virulence for Rph7 appeared in this region in the early 1990s rendering barley cultivars with this gene vulnerable to leaf rust infection. From a preliminary evaluation test, 13 accessions from diverse geographic locations possessed resistance to P. hordei isolate VA90-34, which has virulence for genes Rph1, 2, 4, 6, 7, 8, and 11. Each of these 13 accessions was crossed with susceptible cvs. Moore or Larker to characterize gene number and gene action for resistance to P. hordei. Additionally, the 13 accessions were intercrossed and crossed to host differential lines possessing genes Rph3, Rph5, and Rph9 to determine allelic relationships of resistance genes. Seedlings of F(1), F(2), and BC(1)F(1) populations were evaluated in the greenhouse for their reaction to P. hordei isolate VA90-34. Leaf rust resistance in six of the accessions including Collo sib, CR270.3.2, Deir Alla 105, Giza 119, Gloria, and Lenka is governed by a single dominant gene located at or near the Rph3 locus. All accessions for which the gene Rph3 was postulated to govern leaf rust resistance, except for Deir Alla 105, likely possess an allele different than Rph3.c found in Estate based on the differential reaction to isolates of P. hordei. The resistance gene in Grit and Donan is located at or near the Rph9 locus. Alleles at both the Rph3 and Rph9 loci confer resistance in Femina and Dorina. In addition to Rph3, Caroline and CR366.13.2 likely possess a second unknown recessive gene for leaf rust resistance. Resistance in Carre 180 is governed by a recessive gene that is different from all other genes considered in this study. Identification of both known and unique genes conferring leaf rust resistance in the barley germplasm included in this study provides breeding programs with the knowledge and opportunity to assess currently used sources of leaf rust resistance and to incorporate new sources of resistance into their programs.

Conversion of deoxynivalenol to 3- acetyldeoxynivalenol in barley-derived fuel ethanol co-products with yeast expressing trichothecene 3-O-acetyltransferases

BackgroundThe 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.ResultsTwo 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.ConclusionsThis study demonstrates the potential of using yeast expressing a trichothecene 3-O-acetyltransferase to modify DON during commercial fuel ethanol fermentation.

Variation in Kernel Hardness and Associated Traits in U.S. Barley Breeding Lines

ABSTRACTKernel hardness is an important trait influencing postharvest handling, processing, and food product quality in cereal grains. Though well-characterized in wheat, the basis of kernel hardness is still not completely understood in barley. Kernels of 959 barley breeding lines were evaluated for hardness using the Single Kernel Characterization System (SKCS). Barley lines exhibited a broad range of hardness index (HI) values at 30.1–91.9. Distribution of kernel diameter and weight were 1.7–2.9 mm and 24.9–53.7 mg, respectively. The proportion of hull was 10.2–20.7%. From the 959 breeding lines, 10 hulled spring barley lines differing in HI values (30.1–91.2) were selected to study the associations of HI with proportion of hull, kernel weight, diameter, vitreousness, protein, β-glucan, and amylose content. Vitreousness, evaluated visually using a light box, showed a clear distinction between hard and soft kernels. Hard kernels appeared translucent, while soft kernels appeared opaque when illuminated f...