Browsing by Subject "Hordeum vulgare"

Now showing 1 - 9 of 9
  • Thumbnail Image
    Item
    Amplified fragment length polymorphism and virulence polymorphism in Puccinia hordei
    (Canadian Journal of Plant Pathology, 2007) Sun, Y; Neate, S.M.; Zhong, S; Steffenson, Brian; Friesen, T. L.
    Puccinia hordei is the causal agent of barley leaf rust. To study the genetic diversity in P. hordei, 45 isolates with diverse virulence patterns and geographical origins were analyzed using amplified fragment length polymorphism markers. Two pathotypes of Puccinia graminis f. sp. tritici and one isolate of P. graminis f. sp. secalis were included in the analysis for comparison. Six primer-pair combinations of amplified fragment length polymorphism were used and a total of 782 polymorphic markers were generated. Cluster analysis showed that P. graminis f. sp. tritici and P. graminis f. sp. secalis were distinctly different from P. hordei. The P. hordei isolates were clustered into five groups: group I contained a single, rare isolate that was virulent on all resistance genes except Rph13 and Rph15 ; group II contained a single isolate found to be virulent on the resistance gene Rph15 ; group III contained 2 isolates; group IV contained 24 isolates, 11 from the United States and 13 from diverse locations around the world; and group V contained 17 isolates, 7 from California, 7 from other states of United States, and 3 from central Europe. The study revealed that molecular diversity in P. hordei can be associated with virulence, but not well with geographic origin.
  • Thumbnail Image
    Item
    Effect of incubation time and temperature on the phenotypic expression of rpg4 to Puccinia graminis f. sp. tritici in barley
    (Canadian Journal of Plant Pathology, 1997-03-01) Sun, Yonglian; Steffenson, Brian
    To study the effect of incubation time and temperature on the phenotypic expression of rpg4, five barley genotypes with this resistance gene were infected with pathotype QCCJ of Puccinia graminis f. sp. tritici at the seedling stage, then subjected to various times of incubation at either 18-19°C or 27~28°C. Genotypes with rpg4 exhibited low (0, 0;, and 1), mesothetic (e.g. 3-210;, 120;3), and high (3,3) infection types at 18-19°C after initial incubation at 27-28°C for 0-28, 40-76, and 88 or more hours, respectively. A period of 88 or more hours of initial incubation at high temperature rendered the rpg4 resistance completely ineffective against this pathotype of P. g. f. sp. tritici. In contrast, high, mesothetic, and low infection types were found for the same genotypes at 27-28°C after initial incubation at 18-19°C for 0-40, 52-100, and 112 or more hours, respectively. The resistant infection types conferred by rpg4 are apparently established within the first 112 hours after the end of the infection period since subsequent shifts to higher temperature did not result in marked changes in the resistance response. These data indicate the critical importance of maintaining precise temperature control when assessing the infection phenotypes of barley genotypes carrying the stem rust resistance gene rpg4.
  • Thumbnail Image
    Item
    Genetic variation for virulence and RFLP markers in Pyrenophora teres
    (Canadian Journal of Plant Pathology, 2003-03-01) Wu, H.-L.; Steffenson, Brian; Zhong, S; Li, Y; Oleson, A.E.
    Pyrenophora teres f. teres (causing net blotch) and Pyrenophora teres f. maculata (causing "spot form" of the disease) are important foliar pathogens of barley. In breeding for resistance to disease, it is important to have a thorough knowledge of the degree of genetic variation in the pathogen. This study was undertaken to assess genetic variation in a small, but geographically diverse collection of P. teres isolates. Isolates derived from single conidia were evaluated for their virulence phenotypes on 25 differential barley genotypes. Fifteen pathotypes were identified from a collection of 23 P. t. f. teres isolates, and 4 pathotypes, from a collection of 8 P. t. f. maculata isolates. In general, the P. t. f. teres isolates exhibited a broader spectrum and a higher level of virulence on the host differentials than the P. t. f. maculata isolates. Eight barley genotypes were resistant to all 19 pathotypes identified and should be useful in breeding barley for resistance to both forms of P. teres. Genetic variation was also examined by restriction fragment length polymorphism (RFLP) analysis. A 0.46-kb DNA fragment (ND218) generated by the polymerase chain reaction from genomic DNA of a California isolate of P. t. f. teres was used as a probe. Every P. teres isolate tested with ND218 exhibited a unique RFLP pattern. Cluster analysis, based on both the virulence phenotypes and RFLP patterns, indicates that P. teres possesses a high degree of diversity at the species and subspecies levels. The high degree of polymorphism revealed by ND218 will make this probe a useful tool for the DNA fingerprinting of P. teres isolates.
  • Thumbnail Image
    Item
    Identification and mapping of a leaf rust resistance gene in barley line Q21861
    (Genome, 1997) Steffenson, Brian; Borovkova, I.G.; Jin, Y.; Kilian, A.; Blake, T.K.; Kleinhofs, A.
    Barley line Q21861 possesses an incompletely dominant gene (RphQ) for resistance to leaf rust caused by Puccinia hordei. To investigate the allelic and linkage relations between RphQ and other known Rph genes, F2 populations from crosses between Q21861 and donors of Rph1 to Rph14 (except for Rph8) were evaluated for leaf rust reaction at the seedling stage. Results indicate that RphQ is either allelic with or closely linked to the Rph2 locus. A doubled haploid population derived from a cross between Q21861 and SM89010 (a leaf rust susceptible line) was used for molecular mapping of the resistance locus. Bulked segregant analysis was used to identify markers linked to RphQ, using random amplified polymorphic DNAs (RAPDs), restriction fragment length polymorphisms (RFLPs), and sequence tagged sites (STSs). Of 600 decamer primers screened, amplified fragments generated by 9 primers were found to be linked to the RphQ locus; however, only 4 of them were within 10 cM of the target. The RphQ locus was mapped to the centromeric region of chromosome 7, with a linkage distance of 3.5 cM from the RFLP marker CDO749. Rrn2, an RFLP clone from the ribosomal RNA intergenic spacer region, was found to be very closely linked with RphQ, based on bulked segregant analysis. An STS marker, ITS1, derived from Rrn2, was also closely linked (1.6 cM) to RphQ.
  • Thumbnail Image
    Item
    Identification of Cochliobolus sativus isolates expressing differential virulence on two-rowed barley genotypes from North Dakota
    (Canadian Journal of Plant Pathology, 2009-12-29) Fetch Jr, T.G.; Steffenson, Brian
    Severe spot blotch infection was observed in 1990 on several two-row barley breeding lines previously regarded as resistant to Cochliobolus sativus. Studies were conducted to compare the virulence pattern of a C. sativus isolate (ND90Pr) obtained from this two-row breeding nursery with one (ND85F) used in previous disease screening evaluations. Greenhouse and field experiments were performed in 1991 and 1992 at Fargo, ND, using a split plot design with isolate as the main effect. Isolates ND90Pr and ND85F exhibited distinct differential virulence patterns on barley genotypes ND 5883, ND 12437, ND 12720, ND 12721, and Bowman. Isolate ND90Pr displayed high virulence on ND 12720, ND 12721, and Bowman, and low virulence on ND 5883 and ND 12437. In contrast, isolate ND85F was highly virulent on ND 5883 and ND 12437 and weakly virulent on ND 12720, ND 12721, and Bowman. Both isolates expressed low virulence on genotype ND Bl 12, the primary source of resistance to C. sativus in commercial six-row barley germplasm. To incorporate adequate levels of resistance into future two-row barley cultivars, disease evaluations should be made with C. sativus isolates that express the full spectrum of virulence found in North Dakota.
  • Thumbnail Image
    Item
    Predicting agronomic performance of barley using canopy reflectance data
    (Canadian Journal of Plant Pathology, 2004) Steffenson, Brian; Fetch, T.G.; Pederson, V.D.
    The ability to accurately and rapidly predetermine agronomic performance would be desirable in most plant breeding programs. Remote sensing of canopy reflectance is a quick and nondestructive method that may be useful in the estimation of agronomic performance. Studies were conducted at Fargo and Langdon, North Dakota, to determine the effectiveness of a multispectral radiometer in estimating yield, kernel plumpness (KP), and 1000-kernel weight (TKW) in barley. Canopy reflectance was measured in eight (500–850 nm) discrete narrow-wavelength bands. Three types of reflectance models were evaluated: simple models using one to four wavelengths, simple ratio and normalized difference vegetation indices (NDVI) using green, red, and near-infrared wavelengths, and soil-adjusted vegetation indices (SAVI). The relationship between canopy reflectance and agronomic performance was significantly influenced by environment, growth stage, and plant genotype. Grain yield was best estimated near GS73 (0.84 < R2 < 0.92) at Fargo and at GS83 (0.55 < R2 < 0.81) at Langdon. In contrast, KP and TKW could be estimated at both late (GS83; 0.68 < R2 < 0.93) and early (GS24–GS47; 0.72 < R2 < 0.91) growth stages. The 550-nm and 800-nm wavelengths are critical for development of predictive models. A simple model using 550-nm, 600-nm, and 800-nm from GS47-GS73 gave significant (0.45 < R2 < 0.64) estimation of agronomic performance across all environments. In contrast, simple ratio, NDVI, and SAVI were less effective (0.05 < R2 < 0.77) in predicting agronomic performance. Remote sensing using canopy reflectance is a potential tool to estimate agronomic performance of barley, but genotypic and crop stage factors affect this method. Further studies are needed to improve the usefulness of multispectral radiometry in predicting agronomic performance.
  • Thumbnail Image
    Item
    Reaction of barley seedlings with different stem rust resistance genes to Puccinia graminis f. sp. tritici and P. g. f. sp. secalis
    (Canadian Journal of Plant Pathology, 2005-03-01) Sun, Y; Steffenson, Brian
    Seedling tests are desirable for disease resistance screening in breeding programs because a large number of lines can be evaluated in a short period of time and with modest space requirements. This study was undertaken to identify pathotypes of the wheat stem rust pathogen (Puccinia graminis f. sp. tritici) and cultures of the rye stem rust pathogen (Puccinia graminis f. sp. secalis) that might be useful for detecting resistance genes in barley (Hordeum vulgare) at the seedling stage. Barley accessions with different resistance genes (Rpg1, Rpg2, Rpg3, rpg4, and rpgBH) were assessed for their infection types (ITs) to 13 pathotypes of P. graminis f. sp. tritici and two cultures of P. graminis f. sp. secalis at two temperature regimes (18–21 °C and 24–25 °C). The P. graminis f. sp. tritici pathotypes HKHJ and QCCJ were effective for specifically detecting Rpg1 and rpg4, respectively, and will facilitate resistance breeding efforts. No cultures were found to be effective for specifically detecting the resistance of Hietpas-5, PI 382313, or Black Hulless at the seedling stage. Some pathotypes or cultures did, however, produce low ITs on these sources and will therefore be useful for genetic studies involving crosses with susceptible barleys
  • Thumbnail Image
    Item
    Receptivity of barley to Puccinia graminis f. sp. tritici
    (Canadian Journal of Plant Pathology, 2009-12-29) Steffenson, Brian; Wilcoxson, Roy
    The receptivity of barley genotypes {Hordeum vulgare) was studied in seedlings and adult plants in the greenhouse and in adult plants in the field to races I13-RTQ and 151-QSH of Puccinia graminis f. sp. tritici. In the greenhouse, significant differences in number of uredia/cm2 of leaf were detected due to the effects of races, host genotypes, and their interaction. The cultivar Hiproly was most receptive (had the most uredia) and 80-TT-29 was least receptive (had the fewest uredia) to both races at both growth stages. With race 151-QSH, genotypes with the T-gene, 80-TT-29 and Manker had low weighted infection types (seedling stage), moderately resistant host responses (adult stage), and lower receptivity (both growth stages) than cultivars lacking this gene. With race 113-RTQ, the T-gene was associated with low receptivity only in 80-TT-29. The data suggest that gene(s) other than the T-gene may confer receptivity to P. graminis f. sp. tritici. The ranking of genotypes and the relative differences in receptivity were similar in seedling and adult plants. In the field, genotypes with the T-gene had mostly moderately resistant reactions and fewer uredia than those without the gene. The significant race x host genotype interaction in this study suggests that receptivity in barley varies due to the specific host-parasite combination.
  • Thumbnail Image
    Item
    Sources of resistance to septoria speckled leaf blotch caused by Septoria passernii in barley
    (Canadian Journal of Plant Pathology, 2004-09-01) Toubia-Rahme, H; Steffenson, Brian
    Septoria speckled leaf blotch (SSLB), incited by Septoria passerinii, has reemerged as one of the most serious foliar diseases of barley (Hordeum vulgare) in the Upper Midwest region of the United States over the last decade. The most cost-effective and environmentally safe method of preventing SSLB epidemics is through the use of resistant cultivars. Thus, the objective of this study was to investigate sources of resistance to S. passerinii in barley and to determine the reliability of greenhouse seedling tests for predicting the adult-plant reaction in the field. From a preliminary greenhouse screening of over 250 barley accessions, 78 lines were selected and subsequently evaluated at the seedling (greenhouse) and adult-plant (field) stages for reaction to S. passerinii. All of the major malting (H. vulgare ‘Drummond’, ‘Excel’, ‘Foster’, ‘Lacey’, ‘Legacy’, ‘Morex’, ‘Stander’, ‘Conlon’, and ‘Robust’) and feed (H. vulgare ‘Bowman’, ‘Logan’, and ‘Royal’) cultivars grown in or recommended for the Upper Midwest region of the United States were highly susceptible. Highly significant correlations were detected between the infection response of seedlings in the greenhouse and adult plants in the field. Twenty-nine accessions exhibited resistance at both the seedling and adult-plant stages. The resistant accessions identified in this study were from geographically diverse regions and will be valuable in developing barley cultivars with diverse and broad-based resistance to SSLB.