Scald Resistance In Barley Research Articles

Donors of effective genes for scald resistance in barley

Background. One of the most harmful diseases of barley in all areas of its cultivation is scald. The causal agent Rhynchosporium commune Zaffarano, B.A. McDonald & A. Linde (formerly – Rhynchosporium secalis (Oudem.) J.J. Davis) is characterized by a high level of variability, which leads to the emergence of new pathotypes and the loss of resistance of a number of cultivars. Most barley cultivars recommended for cultivation are highly affected by the pathogen. The aim of the study was to find new donors of effective barley resistance genes to R. commune.Materials and methods. Resistance to the fungus was tested in 99 accessions of barley landraces from 18 countries under laboratory and field conditions. The experiments employed isolates and clones of R. commune isolated from plants collected in Leningrad Province. Plant resistance was scored using point scales. Genetic control of fungal resistance was studied in the selected accessions using hybridological analysis.Results and conclusions. We identified 3 accessions of barley landraces, which retained high resistance to the fungus for six years of study in the field under inoculation with different populations of R. commune. Accessions k-31504 (Macedonia), k-31505 (Ethiopia) and k-31503 (India) are protected by R. commune resistance genes, which differ from each other, are not allelic to the previously identified effective Rrs9 gene, and manifest themselves throughout all stages of barley ontogenesis. Each of accessions k-31504 and k-31505 incorporates 2 recessive pathogen resistance genes; k-31503 carries 3 recessive resistance genes.

Recent insights into barley and Rhynchosporium commune interactions.

Rhynchosporium commune is the causal pathogen of scald in barley (Hordeum vulgare), a foliar disease that can reduce yield by up to 40% in susceptible cultivars. R. commune is found worldwide in all temperate growing regions and is regarded as one of the most economically important barley pathogens. It is a polycyclic pathogen with the ability to rapidly evolve new virulent strains in response to resistance genes deployed in commercial cultivars. Hence, introgression and pyramiding of different loci for resistance (qualitative or quantitative) through marker‐assisted selection is an effective way to improve scald resistance in barley. This review summarizes all 148 resistance quantitative trait loci reported at the date of submission of this review and projects them onto the barley physical map, where it is clear many loci co‐locate on chromosomes 3H and 7H. We have summarized the major named resistance loci and reiterated the renaming of Rrs15 (CI8288) to Rrs17. This review provides a comprehensive resource for future discovery and breeding efforts of qualitative and quantitative scald resistance loci.

Bivariate analysis of barley scald resistance with relative maturity reveals a new major QTL on chromosome 3H

The disease scald of barley is caused by the pathogen Rhynchosporium commune and can cause up to 30–40% yield loss in susceptible cultivars. In this study, the Australian barley cultivar ‘Yerong’ was demonstrated to have resistance that differed from Turk (Rrs1 (Rh3 type)) based on seedling tests with 11 R. commune isolates. A doubled haploid population with 177 lines derived from a cross between ‘Yerong’ and the susceptible Australian cultivar ‘Franklin’ was used to identify quantitative trait loci (QTL) for scald resistance. A QTL on chromosome 3H was identified with large effect, consistent with a major gene conferring scald resistance at the seedling stage. Under field conditions, a bivariate analysis was used to model scald percentage of infected leaf area and relative maturity, the residuals from the regression were used as our phenotype for QTL analysis. This analysis identified one major QTL on chromosome 3H, which mapped to the same position as the QTL at seedling stage. The identified QTL on 3H is proposed to be different from the Rrs1 on the basis of seedling resistance against different R. commune isolates and physical map position. This study increases the current understanding of scald resistance and identifies genetic material possessing QTLs useful for the marker-assisted selection of scald resistance in barley breeding programs.

Investigating Parent Combining Ability and Gene Interactions via Diallel Analysis Against Scald Resistance in Barley

Investigating Parent Combining Ability and Gene Interactions via Diallel Analysis Against Scald Resistance in Barley

オオムギ・イネにおける耐病性,多収性育種の基礎研究および災害復興支援の研究による北陸地域への貢献(北陸作物・育種学会賞(功労賞))

オオムギ・イネにおける耐病性,多収性育種の基礎研究および災害復興支援の研究による北陸地域への貢献(北陸作物・育種学会賞(功労賞))

Pathogenic Groups Identified Among Isolates of Rhynchosporium secalis

Scald, caused by Rhynchosporium secalis has been the major yield-reducing factor for barley production during the last decade. In this study, pathogenic groups of R. secalis were identified to obtain a global picture of the assembly of isolates involved in Syrian populations which is essential for the development of scald-resistant barley cultivars. To identify a number of pathogenic groups, 49 isolates collected over ten years from major barley growing areas in Syria were evaluated on five differential barley genotypes. Genotypes presented a continuous range of response from highly susceptible to moderately resistant, but none were immune to the disease. A cluster analysis placed isolates in six distinct differential pathogenic groups. Mean disease rating of 39.24% was the separation point between avirulent and virulent reactions. Isolate Rs46 exhibited distinct differential virulence patterns associated with high frequency across all genotypes. Hence, the data presented here provides crucial information for future selection of isolates to develop durable barley scald resistance.

MOLECULAR AND PATHOGENIC VARIATION IDENTIFIED AMONG ISOLATES OF RHYNCHOSPORIUM SECALIS FROM SYRIA

The fungus Rhynchosporium secalis is the causal agent of barley scald disease. Sixty-three isolates of diverse geographical origin within Syria were analyzed for pathogenicity and variability of genomic DNA through random amplified polymorphic DNA (RAPD) markers. The isolates were highly variable and 18 unique haplotypes were identified. A neighbour-joining diagram, based on Nei’s genetic distances, showed that isolates formed three phylogenetic groups, and did not fall into clusters linked with geographical origin or pathogenicity, which suggests a regional dispersal of the fungus. However, most isolates with different pathogenicity levels were in the same clusters. The information obtained from this study is crucial for studying genetic variation in R. secalis and is important for future selection of isolates to develop durable barley scald resistance.

Identification of QTLs for powdery mildew and scald resistance in barley

A population of 103 recombinant inbred lines (RILs, F9-derived lines) developed from the two-row spring barley cross L94 × ‘Vada’ was evaluated under field conditions for resistance against powdery mildew (Blumeria graminis f.sp. hordei) and scald (Rhynchosporium secalis). Apart from the major resistance gene mlo on chromosome 4 (4H), three QTLs (Rbgq1, Rbgq2 and Rbgq3) for resistance against powdery mildew were detected on chromosomes 2 (2H), 3 (3H), and 7 (5H), respectively. Rbgq1 and Rbgq2 have not been reported before, and did not map to a chromosome region where a major gene for powdery mildew had been reported. Four QTLs (Rrsq1, Rrsq2, Rrsq3 and Rrsq4) for resistance against scald were detected on chromosomes 3 (3H), 4 (4H) and 6 (6H). All four mapped to places where QTLs for scald resistance had been reported before in different populations.

A novel barley scald resistance gene: genetic mapping of the Rrs15 scald resistance gene derived from wild barley, Hordeum vulgare ssp. spontaneum

Most genes for resistance to barley leaf scald map either to the Rrs1 locus on the long arm of chromosome 3H, or the Rrs2 locus on the short arm of chromosome 7H. Other loci containing scald resistance genes have previously been identified using lines derived from wild barley, Hordeum vulgare ssp. spontaneum. A single dominant gene conditioning resistance to scald was identified in a third backcross (BC 3 F 3 ) line derived from an Israeli accession of wild barley. The resistance gene is linked to three microsatellite markers that map to the long arm of chromosome 7H; the closest of these loci, HVM49, maps 11.5 cM from the resistance gene. As no other scald resistance genes have been mapped to this chromosome arm, it is considered to be a novel scald resistance locus. As the Acp2 isozyme locus is linked to this scald resistance locus, at 17.7 cM, Acp2 is assigned to chromosome 7H. Molecular markers linked to the novel scald resistance gene, designated Rrv15, can be used in breeding for scald resistance.

Quantitative trait loci for scald resistance in barley localized by a non‐interval mapping procedure

AbstractThree quantitative trait loci (QTL) for scald resistance in barley were identified and mapped in relation to molecular markers using a population of chromosome doubled‐haploid lines produced from the F1 generation of a cross between the spring barley varieties ‘Alexis’ and ‘Regatta’. Two field experiments were conducted in Denmark and two in Norway to assess disease resistance. The percentage leaf area covered with scald (Rhynchosporium secalis) ranged from 0 to 40% in the 189 doubled‐haploid (DH) lines analysed. One quantitative trait locus was localized in the centromeric region of chromosome 3H, Qryn3, using the MAPQTL program. MAPQTL was unable to provide proper localization of the other two resistance genes and so a non‐interval QTL mapping method was used. One was found to be located distally to markers on chromosome 4H (Qryn4) and the other, Qryn6, was located distally to markers on chromosome 6H. The effects of differences between the Qryn3, Qryn4 and Qryn6 alleles in two barley genotypes for the QTL were estimated to be 8.8%, 7.3% and 7.0%, respectively, of leaf covered by scald. No interactions between the QTLs were found.

Genetic mapping of the barley Rrs14 scald resistance gene with RFLP, isozyme and seed storage protein markers

AbstractThe scald susceptible barley cultivar ‘Clipper’ and a third‐backcross (BC3) line homozygous for the Rrs14 scald resistance gene that originally came from Hordeum vulgare ssp. spontaneum were grown in replicated field trials. The level of resistance that Rrs14 confers against field populations of the pathogen Rhynchosporium secalis, the causal agent of scald disease, was evaluated. The Rrs14 BC3 line exhibited 80% and 88% less leaf damage than ‘Clipper’ in 1995 and 1996, respectively. Given this effectiveness of Rrs14, research was undertaken to identify a linked marker locus suitable for indirect selection of Rrs14. Based on linkage to a set of previously mapped loci, Rrs14 was positioned to barley chromosome 1H between the seed storage protein (hordein) loci Hor1 and Hor2, approximately 1.8 cM from the latter locus. The Hor2 locus is thus an ideal codominant molecular marker for Rrs14. The tight linkage between Rrs14 and Hor2 and the availability of alternative biochemical and molecular techniques for scoring Hor2 genotypes, permits simple indirect selection of Rrs14 in barley scald resistance breeding programmes.

Genetic Analysis of Changes in Scald Resistance in Barley Composite Cross V

Genetic Analysis of Changes in Scald Resistance in Barley Composite Cross V

Sources and Use of Scald Resistance in Barley1

Agronomy JournalVolume 40, Issue 10 p. 926-928 Article Sources and Use of Scald Resistance in Barley1 O. C. Riddle, O. C. RiddleSearch for more papers by this authorC. A. Suneson, C. A. Suneson Private Consulting Agronomist, formerly Assistant Professor, University of California: and Agronomist, respectively.Search for more papers by this author O. C. Riddle, O. C. RiddleSearch for more papers by this authorC. A. Suneson, C. A. Suneson Private Consulting Agronomist, formerly Assistant Professor, University of California: and Agronomist, respectively.Search for more papers by this author First published: 01 October 1948 https://doi.org/10.2134/agronj1948.00021962004000100010xCitations: 8 1 Contribution from the Agronomy Division, University of California, Davis, Calif., and the Division of Cereal Crops and Diseases, Bureau of Plant Industry, Soils, and Agricultural Engineering, Agricultural Research Administration, U. S. Dept. of Agriculture, cooperating. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume40, Issue10October 1948Pages 926-928 RelatedInformation