scholarly journals MILDEW LOCUS O Mutation Does Not Affect Resistance to Grain Infections with Fusarium spp. and Ramularia collo-cygni

2015 ◽  
Vol 105 (9) ◽  
pp. 1214-1219 ◽  
Author(s):  
Katharina Hofer ◽  
Andrea Linkmeyer ◽  
Katharina Textor ◽  
Ralph Hückelhoven ◽  
Michael Hess
Keyword(s):  
Cell Death ◽  
Powdery Mildew ◽  
Fungal Pathogens ◽  
Powdery Mildew Resistance ◽  
Natural Infection ◽  
Spring Barley ◽  
Susceptibility Gene ◽  
Fusarium Spp ◽  
Mildew Resistance ◽  
Barley Powdery Mildew

MILDEW LOCUS O defines a major susceptibility gene for powdery mildew, and recessive mlo resistance alleles are widely used in breeding for powdery mildew resistance in spring barley. Barley powdery mildew resistance, which is conferred by mlo genes, is considered to be costly in terms of spontaneous defense reactions and enhanced susceptibility to cell-death-inducing pathogens. We assessed fungal infestation of barley (Hordeum vulgare) grain by measuring fungal DNA after natural infection with Fusarium spp. and Ramularia collo-cygni or after inoculation with Fusarium spp. in the field. Powdery-mildew-resistant mlo5 genotypes did not show enhanced Fusarium spp. or R. collo-cygni DNA content of grain over four consecutive years. Data add to our understanding of pleiotropic effects of mlo-mediated powdery mildew resistance and contributes to the discussion of whether or not application of barley mlo mutations may support pathogenesis of cell-death-inducing fungal pathogens under field conditions.

scholarly journals Virulence frequencies to powdery mildew resistance genes of winter barley cultivars

2010 ◽  
Vol 40 (No. 4) ◽  
pp. 135-140 ◽  
Author(s):  
A. Dreiseitl
Keyword(s):  
Czech Republic ◽  
Powdery Mildew ◽  
Resistance Genes ◽  
Powdery Mildew Resistance ◽  
Spring Barley ◽  
Winter Barley ◽  
The Czech Republic ◽  
Mildew Resistance ◽  
Barley Cultivars ◽  
Random Samples

The virulence frequencies to powdery mildew resistance genes possessed by winter barley cultivars registered and newly tested in the Czech Republic were studied in 2000, 2002 and 2004. Random samples of the populations originating from winter and spring barley fields were obtained from the air by a mobile version of a jet spore sampler mounted on a car roof. Conidia were sampled by driving across the Czech Republic. Fourteen differentials, carrying 18 out of 20 currently identified resistance genes present in winter barley cultivars, were used. High virulence frequencies (85–100%) to most resistance genes were found. Lower virulence frequencies (14.1–40.1%) were found to only three resistance genes that have not been described yet; their preliminary designations are Ml(Va), Ml(Dt) and Ml(Ca). The importance of resistance of winter barley cultivars is discussed with respect to limiting the speed with which the pathogen adapts to genetic resistances possessed by commercial cultivars of both winter and spring barley, and to the necessity of lowering the costs for powdery mildew control in barley.

scholarly journals Selections from barley landrace collected in Libya as new sources of effective resistance to powdery mildew (Blumeria graminis f.sp. hordei)

2011 ◽  
Vol 48 (No. 5) ◽  
pp. 217-223 ◽  
Author(s):  
J.H. Czembor ◽  
H.J. Czembor
Keyword(s):  
Powdery Mildew ◽  
Powdery Mildew Resistance ◽  
Agricultural Research ◽  
Genetic Resistance ◽  
Recessive Gene ◽  
Blumeria Graminis ◽  
Hordeum Vulgare L ◽  
Mildew Resistance ◽  
Barley Landrace ◽  
Barley Powdery Mildew

Powdery mildew on barley (Hordeum vulgare L.) caused by the pathogen Blumeria graminis f.sp. hordei occurs worldwide and can result in severe yield loss. Because agronomical methods to control the disease are not completely effective, cultivars with genetic resistance are needed. Therefore, there is a need to describe new sources of genes that confer resistance to barley powdery mildew. This study was conducted to determine the genetic basis of resistance to powdery mildew in three selections 995-1-1, 995-1-2, 995-1-3 from barley landrace 995 (ICB 112840) collected in Al Aziziyah district, Tripolitania, Libya. Landrace originated from InternationalCenter for Agricultural Research in the Dry Areas – ICARDA, Aleppo, Syria. To determine the number of genes, the types of genes action and the gene loci in tested lines two types of crosses were made: (1) the lines were crossed to the susceptible cultivar Pallas, (2) the lines were crossed with Pallas isoline P22 carrying gene mlo5. The parents and progeny F2 were evaluated with isolate R303.1 for the powdery mildew resistance. Based on segregation ratios we found that resistance in these three selections was determined by a single recessive gene allelic to the Mlo locus occurring in Pallas isoline P22. In addition tested lines showed resistance reaction type 0(4) characteristic only for genes mlo. The value of new identified sources of highly effective powdery mildew resistance to breeding programs and barley production is discussed.

Powdery Mildew Resistance Genes in 127 Northwest European Spring Barley Varieties

1992 ◽  
Vol 108 (3) ◽  
pp. 210-228 ◽  
Author(s):  
H. P. Jensen ◽  
E. Christensen ◽  
J. Helms Jorgensen
Keyword(s):  
Powdery Mildew ◽  
Resistance Genes ◽  
Powdery Mildew Resistance ◽  
Spring Barley ◽  
Mildew Resistance

scholarly journals Powdery Mildew Resistance of Foreign Spring Barley Varieties in Czech Official Trials

2011 ◽  
Vol 42 (No. 1) ◽  
pp. 1-8 ◽  
Author(s):  
A. Dreiseitl
Keyword(s):  
Powdery Mildew ◽  
Powdery Mildew Resistance ◽  
Spring Barley ◽  
Mildew Resistance ◽  
Homogeneous Varieties

In 1993–2005, resistance to powdery mildew was studied in 168 foreign varieties of spring barley included in Czech Official Trials in that period. Sixteen known resistances to powdery mildew were identified (Ab, Al, Ar, HH, Kw, La, Ly, MC, Mlo, N81, Ri, Ru, Sp, St, Tu, and We). Unknown resistances were found in 32 varieties, in nine of which these resistances were effective against all used pathotypes of the pathogen. Seven varieties (= 5%) exhibited heterogeneity in the examined trait, i.e. they are composed of lines (usually of two) with different resistances to powder mildew. The resistance Mlo, which was found in 75 homogeneous varieties (= 46%), dominated in the set. The resistances Ru, We, Ar and La were frequently present. The examined set includes 53% of varieties resistant to all used indigenous pathotypes of the pathogen.  

scholarly journals Powdery Mildew Resistance of Czech and Slovak Spring Barley Breeding Lines in Variety Trials

2011 ◽  
Vol 41 (No. 4) ◽  
pp. 160-166 ◽  
Author(s):  
A. Dreiseitl
Keyword(s):  
Powdery Mildew ◽  
Considerable Increase ◽  
Powdery Mildew Resistance ◽  
Spring Barley ◽  
Mildew Resistance ◽  
Breeding Lines ◽  
Breeding Station ◽  
Low Diversity ◽  
Mla Locus ◽  
The Given

In 2001–2005, resistance to powdery mildew was studied in 227 Czech and Slovak breeding lines of spring barley included in the breeding station trials or official trials. Seventeen known resistances were identified (Al, Ar, At, HH, Kr, La, Ly, Mlo, N81, Ri, Ru, Sp, St, Tu, We, Mla21, and Mlp1). Unknown resistances were found in 11 breeding lines, in five of which resistance was effective against all used pathotypes of the pathogen. Besides the identified resistances, unknown resistances were detected in another three breeding lines. Sixty-five breeding lines (= 29%) exhibited heterogeneity in the examined trait, i.e. they are composed of components with different resistances to powdery mildew. Comparison of current results with the previous ones shows a considerable increase in the proportion of breeding lines carrying the resistance Mlo (72%), on the account of the resistances located at the Mla locus, particularly Ru. The examined set is characterised by a high proportion of breeding lines resistant to all used Czech pathotypes of the given pathogen (78%), however of low diversity in the resistance.  

scholarly journals Lessons from a Phenotyping Center Revealed by the Genome-Guided Mapping of Powdery Mildew Resistance Loci

2016 ◽  
Vol 106 (10) ◽  
pp. 1159-1169 ◽  
Author(s):  
Lance Cadle-Davidson ◽  
David Gadoury ◽  
Jonathan Fresnedo-Ramírez ◽  
Shanshan Yang ◽  
Paola Barba ◽  
...  
Keyword(s):  
High Resolution ◽  
Powdery Mildew ◽  
Host Resistance ◽  
Powdery Mildew Resistance ◽  
Natural Infection ◽  
Genotyping By Sequencing ◽  
Developmentally Regulated ◽  
Mildew Resistance ◽  
Powdery Mildews ◽  
Trait Locus

The genomics era brought unprecedented opportunities for genetic analysis of host resistance, but it came with the challenge that accurate and reproducible phenotypes are needed so that genomic results appropriately reflect biology. Phenotyping host resistance by natural infection in the field can produce variable results due to the uncontrolled environment, uneven distribution and genetics of the pathogen, and developmentally regulated resistance among other factors. To address these challenges, we developed highly controlled, standardized methodologies for phenotyping powdery mildew resistance in the context of a phenotyping center, receiving samples of up to 140 grapevine progeny per F1 family. We applied these methodologies to F1 families segregating for REN1- or REN2-mediated resistance and validated that some but not all bioassays identified the REN1 or REN2 locus. A point-intercept method (hyphal transects) to quantify colony density objectively at 8 or 9 days postinoculation proved to be the phenotypic response most reproducibly predicted by these resistance loci. Quantitative trait locus (QTL) mapping with genotyping-by-sequencing maps defined the REN1 and REN2 loci at relatively high resolution. In the reference PN40024 genome under each QTL, nucleotide-binding site−leucine-rich repeat candidate resistance genes were identified—one gene for REN1 and two genes for REN2. The methods described here for centralized resistance phenotyping and high-resolution genetic mapping can inform strategies for breeding resistance to powdery mildews and other pathogens on diverse, highly heterozygous hosts.

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