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Plants use a sophisticated immune system to perceive pathogen infection and activate immune responses in a tightly controlled manner. In barley, HvWRKY2 acts as a repressor in barley disease resistance to the powdery mildew fungus, Blumeria graminis f. sp. hordei (Bgh). However, the molecular features of HvWRKY2 in its DNA-binding and repressor functions, as well as its target genes, are uncharacterized. We show that the W-box binding of HvWRKY2 requires an intact WRKY domain and an upstream sequence of -75 amino acids, and the HvWRKY2 W-box binding activity is linked to its repressor function in disease resistance. Chromatin immunoprecipitation (ChIP)-seq analysis identified HvCEBiP, a putative chitin receptor gene, as a target gene of HvWRKY2 in overexpressing transgenic barley plants. ChIP-qPCR and Electrophoretic Mobility Shift Assay (EMSA) verified the direct binding of HvWRKY2 to a W-boxcontaining sequence in the HvCEBiP promoter. HvCEBiP positively regulates resistance against Bgh in barley. Our findings suggest that HvWRKY2 represses barley basal immunity by directly targeting pathogen-associated molecular pattern (PAMP) recognition receptor genes, suggesting that HvCEBiP and likely chitin signaling function in barley PAMP-triggered immune responses to Bgh infection. [ABSTRACT FROM AUTHOR]

Breeding for adult plant resistance (APR) is currently impeded by the low frequency of annual field‐based testing and variable environmental conditions. We developed and implemented a greenhouse‐based methodology for the rapid phenotyping of APR to leaf rust in barley to improve the efficacy of gene discovery and cloning. We assessed the effects of temperature (18 and 23°C) and growth stage (1–5 weeks) on the expression of APR in the greenhouse using 28 barley genotypes with both known and uncharacterized APR. All lines were susceptible in week 1, while lines carrying Rph20 and several with uncharacterized resistance expressed resistance as early as week 2. In contrast, lines lacking Rph20 and carrying either Rph23 and/or Rph24 expressed resistance from week 4. Resistant phenotypes were clearest at 18°C. A subset of 16 of the 28 lines were assessed for leaf rust across multiple national and international field sites. The greenhouse screening data reported in this study were highly correlated to most of the field sites, indicating that they provide comparable data on APR phenotypes for screening purposes. [ABSTRACT FROM AUTHOR]

Barley phylloplane is seriously colonized by Drechslera graminea, the causal agent of leaf stripe disease in the hos. The present study involved the elucidation of alterations induced in the protein content of the host due to Drechslera infection. Naturally growing barley plants were obtained from fields and Drechslera graminea was isolated and identified from diseased plants' leaves. After identification and preparation of the pure culture, the pathogen was inoculated on plants grown under aseptic and controlled laboratory conditions. Changes in the total soluble cytoplasmic proteins and defense enzymes of the host such as polyphenol oxidase (PPO), peroxidase (POX), phenylalanine lyase (PAL) and tyrosine ammonia lyase (TAL) were observed up to 5 h after inoculation. The results demonstrated a significant effect of the pathogen on the cytoplasmic protein expression of the host as well as in its defense system. [ABSTRACT FROM AUTHOR]

Key message: Resistance factors against non-adapted powdery mildews were mapped in barley. Some QTLs seem effective only to non-adapted mildews, while others also play a role in defense against the adapted form.The durability and effectiveness of nonhost resistance suggests promising practical applications for crop breeding, relying upon elucidation of key aspects of this type of resistance. We investigated which genetic factors determine the nonhost status of barley (Hordeum vulgare L.) to powdery mildews (Blumeria graminis). We set out to verify whether genes involved in nonhost resistance have a wide effectiveness spectrum, and whether nonhost resistance genes confer resistance to the barley adapted powdery mildew. Two barley lines, SusBgtSC and SusBgtDC, with some susceptibility to the wheat powdery mildew B. graminis f.sp. tritici (Bgt) were crossed with cv Vada to generate two mapping populations. Each population was assessed for level of infection against four B. graminis ff.spp, and QTL mapping analyses were performed. Our results demonstrate polygenic inheritance for nonhost resistance, with some QTLs effective only to non-adapted mildews, while others play a role against adapted and non-adapted forms. Histology analyses of nonhost interaction show that most penetration attempts are stopped in association with papillae, and also suggest independent layers of defence at haustorium establishment and conidiophore formation. Nonhost resistance of barley to powdery mildew relies mostly on non-hypersensitive mechanisms. A large-effect nonhost resistance QTL mapped to a 1.4 cM interval is suitable for map-based cloning. [ABSTRACT FROM AUTHOR]

Quantitative resistance in barley to four Fusarium head blight (FHB) species was investigated in vitro. Nine components involved in three assays (detached leaf, modified Petridish and seedling tests) were compared on two widely grown Syrian barley cultivars: Arabi Aswad (AS) and Arabi Abiad (AB). On AB, inoculation with FHB species resulted in a significantly shorter latent period and larger lesion length of detached leaf inoculation, more standardized area under disease progress curve (AUDPCstandard) of modified Petridish inoculation and a higher percentage of infected seedlings of pin-point inoculation than on AS. The latent period of AB was 14.89% less than AS, lesion length of AS was 6.01% less than AB, AUDPCstandard of AS was 17.07% less than AB and the percentage of infected seedlings of AS was 4.87% less than AB. Inoculation with FHB species resulted in no significant differences in the other five components measured: incubation period of detached leaf inoculation, germination rate reduction and coleoptile length reduction of modified Petridish inoculation, percentage of infected seedlings of foliar-spraying inoculation and lesion length of clip-dipping inoculation. AS was more resistant to in vitro FHB infection than AB. The latent period and AUDPCstandard recorded the highest values compared with the lowest values for lesion length and percentage of infected seedlings. It seems that measurement of the latent period and AUDPCstandard may be useful in identifying barley cultivars which are highly susceptible or resistant to FHB at early stages. [ABSTRACT FROM AUTHOR]

The fungal disease barley stripe rust (BSR, causal agent Puccinia striiformis f. sp. hordei) can greatly reduce yield and quality of malt barley (Hordeum vulgare L.), a valuable crop in the distilling and brewing industries. Yield losses of up to 70% have been reported. Resistant cultivars are the most sustainable defense against BSR, especially those cultivars with pyramids of quantitative disease resistance (QDR) genes. The Oregon State University (OSU) barley breeding program has selected for BSR resistance for decades and has released cultivars with BSR resistance. We wanted to determine the number and effect of the loci underlying that resistance, as well as whether it was conferred by QDR or race-specific qualitative loci. To test these, we used BSR resistance quantitative trait loci (QTL) mapping via genomewide association studies (GWAS) in adult-plant field trials (3 yr, one location) and race-specific seedling greenhouse trials (five races). The FAC-WIN6, a GWAS panel composed of 300 lines that represent the OSU and University of Minnesota facultative and winter six-rowed malt barley breeding programs, was used in genotyping and phenotyping. The FAC-WIN6 was developed as part of the USDA-ARS Triticeae Coordinated Agricultural Project but was not developed specifically for BSR resistance. In total, we detected three race-specific QTL in greenhouse trials (one of which was also significant in field trials) and 14 QTL significant in field trials only with 2.3 to 20.7% additive reduction in percentage disease severity. At least five QTL were considered novel. These results indicated that the OSU breeding program had both QDR and race-specific loci for BSR resistance. We suspected that its BSR resistance distributions in the FAC-WIN6 might align with the major population structure patterns in ways that would be difficult to account for with a GWAS model alone. Therefore, based on post hoc diagnostics, we report a qualitative "usability" level for each QTL. [ABSTRACT FROM AUTHOR]

Key message: QTL conferring a 14-40% reduction in adult plant stem rust severity to multiple races of Pgt were found on chromosome 5H and will be useful in barley breeding. Abstract: Stem rust, caused by Puccinia graminis f. sp. tritici ( Pgt) is an important disease of barley. The resistance gene Rpg1 has protected the crop against stem rust losses for over 70 years in North America, but is not effective against the African Pgt race TTKSK (and its variants) nor the domestic race QCCJB. To identify resistance to these Rpg1-virulent races, the Barley iCore Collection, held by the United States Department of Agriculture-Agricultural Research Service National Small Grains Collection was evaluated for adult plant resistance (APR) and seedling resistance to race TTKSK and APR to race QCCJB and the Pgt TTKSK composite of races TTKSK, TTKST, TTKTK, and TTKTT. Using a genome-wide association study approach based on 6224 single nucleotide polymorphic markers, seven significant loci for stem rust resistance were identified on chromosomes 1H, 2H, 3H, and 5H. The most significant markers detected were 11_11355 and SCRI_RS_177017 at 71-75 cM on chromosome 5H, conferring APR to QCCJB and TTKSK composite. Significant markers were also detected for TTKSK seedling resistance on chromosome 5H. All markers detected on 5H were independent of the rpg4/Rpg5 complex at 152-168 cM. This study verified the importance of the 11_11355 locus in conferring APR to races QCCJB and TTKSK and suggests that it may be effective against other races in the Ug99 lineage. [ABSTRACT FROM AUTHOR]

In this study, we characterized and mapped a new and rare resistance gene ( Rph FT) in the Chinese barley variety 'Fong Tien'. Rph FT, a dominant gene, was mapped to chromosome 5 HL at a genetic position of 142.1 cM using DArT-seq markers. The gene was also confirmed to be present in Australian cultivar 'Yagan' based on allelic tests, and likely 'Lockyer' based on multipathotype tests. The genetic studies also confirmed the presence of Rph12 in Australian cultivar 'Baudin'. Rph12 is also located on chromosome 5 HL close to Rph FT, and the two loci were confirmed to be independent. Gene Rph FT is of limited breeding value because it is effective to only one pathotype of P. hordei, 220P+ + Rph13 in Australia; nevertheless, it may play a role in controlling leaf rust if used in combination with other Rph genes. The locus symbol Rph25 is recommended for Rph FT in accordance with the rules and numbering system of barley gene nomenclature. [ABSTRACT FROM AUTHOR]

Differences in early plant-pathogen interactions are mainly characterized by using destructive methods. Optical sensors are advanced techniques for phenotyping host-pathogen interactions on different scales and for detecting subtle plant resistance responses against pathogens. A microscope with a hyperspectral camera was used to study interactions between Blumeria graminis f. sp. hordei and barley (Hordeum vulgare) genotypes with high susceptibility or resistance due to hypersensitive response (HR) and papilla formation. Qualitative and quantitative assessment of pathogen development was used to explain changes in hyperspectral signatures. Within 48 h after inoculation, genotype-specific changes in the green and red range (500 to 690 nm) and a blue shift of the red-edge inflection point were observed. Manual analysis indicated resistance-specific reflectance patterns from 1 to 3 days after inoculation. These changes could be linked to host plant modifications depending on individual host-pathogen interactions. Retrospective analysis of hyperspectral images revealed spectral characteristics of HR against B. graminis f. sp. hordei. For early HR detection, an advanced data mining approach localized HR spots before they became visible on the RGB images derived from hyperspectral imaging. The link among processes during pathogenesis and host resistance to changes in hyperspectral signatures provide evidence that sensor-based phenotyping is suitable to advance time-consuming and cost-expensive visual rating of plant disease resistances. [ABSTRACT FROM AUTHOR]

Key message: Genome-wide association studies of barley breeding populations identified candidate minor genes for pairing with the adult plant resistance gene Rph20 to provide stable leaf rust resistance across environments. Abstract: Stable resistance to barley leaf rust (BLR, caused by Puccinia hordei) was evaluated across environments in barley breeding populations (BPs). To identify genomic regions that can be combined with Rph20 to improve adult plant resistance (APR), two BPs genotyped with the Diversity Arrays Technology genotyping-by-sequencing platform (DArT-seq) were examined for reaction to BLR at both seedling and adult growth stages in Australian environments. An integrated consensus map comprising both first- and second-generation DArT platforms was used to integrate QTL information across two additional BPs, providing a total of four interrelated BPs and 15 phenotypic data sets. This enabled identification of key loci underpinning BLR resistance. The APR gene Rph20 was the only active resistance region consistently detected across BPs. Of the QTL identified, RphQ27 on chromosome 6HL was considered the best candidate for pairing with Rph20. RphQ27 did not align or share proximity with known genes and was detected in three of the four BPs. The combination of RphQ27 and Rph20 was of low frequency in the breeding material; however, strong resistance responses were observed for the lines carrying this pairing. This suggests that the candidate minor gene RphQ27 can interact additively with Rph20 to provide stable resistance to BLR across diverse environments. [ABSTRACT FROM AUTHOR]

Background: The harsh environment on the Qinghai-Tibetan Plateau gives Tibetan hulless barley (Hordeum vulgare var. nudum) great ability to resist adversities such as drought, salinity, and low temperature, and makes it a good subject for the analysis of drought tolerance mechanism. To elucidate the specific gene networks and pathways that contribute to its drought tolerance, and for identifying new candidate genes for breeding purposes, we performed a transcriptomic analysis using two accessions of Tibetan hulless barley, namely Z772 (drought-tolerant) and Z013 (drought-sensitive). Results: There were more up-regulated genes of Z772 than Z013 under both mild (5439-VS-2604) and severe (7203-VS-3359) dehydration treatments. Under mild dehydration stress, the pathways exclusively enriched in droughttolerancegenotype Z772 included Protein processing in endoplasmic reticulum, tricarboxylic acid (TCA) cycle, Wax biosynthesis, and Spliceosome. Under severe dehydration stress, the pathways that were mainly enriched in Z772 included Carbon fixation in photosynthetic organisms, Pyruvate metabolism, Porphyrin and chlorophyll metabolism. The main differentially expressed genes (DEGs) in response to dehydration stress and genes whose expression was different between tolerant and sensitive genotypes were presented in this study, respectively. The candidate genes for drought tolerance were selected based on their expression patterns. Conclusions: The RNA-Seq data obtained in this study provided an initial overview on global gene expression patterns and networks that related to dehydration shock in Tibetan hulless barley. Furthermore, these data provided pathways and a targeted set of candidate genes that might be essential for deep analyzing the molecular mechanisms of plant tolerance to drought stress. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Barley ( Hordeum vulgare) is cultivated on 49.1 million hectares worldwide with 50.2% of the area located in Europe. Powdery mildew, caused by Blumeria graminis f. sp. hordei ( Bgh), occurs wherever barley is grown. Cultivar resistance plays an important role in global barley production, especially in parts of Europe where high concentrations of both spring and winter types are grown. The aim of this report was to postulate specific resistance genes in barleys from nine European countries registered in the Czech Republic from 2011 to 2015. Thirty-five spring cultivars and 27 winter barleys were tested with 56 diverse Bgh isolates. Twenty-five known resistance genes were postulated, and unknown genes were detected in Sandra, Saturn and Zeppelin. Unidentified specific resistance genes were also present in winter hybrids Hobbit and Wootan. Spring cultivars Arthur and Francin consisted of three and two genotypes, respectively. Resistance gene mlo was present in 26 spring cultivars, and the proportion of cultivars with this gene increased from 62.9% in 2006-2010 to 75.7% in 2011-2015. The gene Mlp1 was identified for the first time in German winter cultivar Saturn. Five spring cultivars registered in Slovakia were included in the tests. All the cultivars that were tested contained one or more specific resistance genes to powdery mildew. Adaptability of the pathogen and possibilities for breeding winter barleys are discussed. [ABSTRACT FROM AUTHOR]

Partial resistance quantitative trait loci (QTLs) Rphq11 and rphq16 against Puccinia hordei isolate 1.2.1 were previously mapped in seedlings of the mapping populations Steptoe/Morex and Oregon Wolfe Barleys, respectively. In this study, QTL mapping was performed at adult plant stage for the two mapping populations challenged with the same rust isolate. The results suggest that Rphq11 and rphq16 are effective only at seedling stage, and not at adult plant stage. The cloning of several genes responsible for partial resistance of barley to P. hordei will allow elucidation of the molecular basis of this type of plant defence. A map-based cloning approach requires to fine-map the QTL in a narrow genetic window. In this study, Rphq11 and rphq16 were fine-mapped using an approach aiming at speeding up the development of plant material and simplifying its evaluation. The plant materials for fine-mapping were identified from early plant materials developed to produce QTL-NILs. The material was first selected to carry the targeted QTL in heterozygous condition and susceptibility alleles at other resistance QTLs in homozygous condition. This strategy took four to five generations to obtain fixed QTL recombinants (i.e., homozygous resistant at the Rphq11 or rphq16 QTL alleles, homozygous susceptible at the non-targeted QTL alleles). In less than 2 years, Rphq11 was fine-mapped into a 0.2-cM genetic interval and a 1.4-cM genetic interval for rphq16. The strongest candidate gene for Rphq11 is a phospholipid hydroperoxide glutathione peroxidase. Thus far, no candidate gene was identified for rphq16. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Barley (Hordeum vulagare L) is the major crop for the people living in the high hills and mountainous region of Nepal. Leaf rust (caused by Puccinia hordei) is one of the major production threats for barley cultivation. A lot of variation can be observed on Nepalese barley accessions with respect to leaf rust resistance characteristics. Two hundred and forty one barley accessions were screened for leaf rust resistance characteristics on heading stage at Khumaltar, Lalitpur, Nepal. Among them, one hundred and nine Nepalese barley accessions showing promising for disease resistance were screened using six SSR markers linked to leaf rust resistance genes. Bonus and Local Jau was used as the resistant and susceptible check respectively. Leaf rust resistance genes Rph1, Rph2, Rph3, Rph7, QBLR-P and QTL on chromosome 5HS were detected on Nepalese barley accessions using respective SSR markers. Eight Nepalese barley accessions showed presence of three and more leaf rust resistant genes. The poor relationship between the field disease resistance and molecular markers linked with specific leaf rust resistance gene proved that Nepalese barley gene pool contains other leaf resistance genes. [ABSTRACT FROM AUTHOR]

The barley ( Hordeum vulgare L.) mutant erectoides-k.32 ( ert-k.32) was isolated in 1947 from an X-ray-mutant population of cultivar 'Bonus'. The mutant was released as a cultivar in 1958 with the name 'Pallas' - one of the first cereal crop cultivars developed from induced mutants. 'Pallas' is a semi-dwarf barley cultivar known for its culm stability and resistance to lodging. In total, eight allelic ert-k mutants are known that show different phenotypic strength concerning culm length and spike architecture. They represent alternatives to the widely used, but pleiotropic 'Green Revolution' alleles of the Sdw1 ( semidwarf1/denso) and Uzu1 ( semi-brachytic1) genes in breeding of robust elite barley cultivars. In the present study, we locate Ert-k to a 15.7- cM region in the centromeric region of chromosome 6H. Although the interval is estimated to contain approximately 700 genes, the work provides a solid foundation for the identification of the underlying mutations causing the ert-k lodging-resistant phenotype. In addition, the linked markers could be used to follow the ert-k mutant genotype in marker-assisted selection of new lodging-resistant barley cultivars. [ABSTRACT FROM AUTHOR]

Key message: This study describes the generation, screening, genetic and molecular characterization, and high-resolution mapping of barley mutants susceptible to stem rust ( Puccinia graminis f. sp. tritici ) races MCCF and HKHJ. Abstract: A single gene, Rpg1, has protected barley cultivars against many races of stem rust pathogen ( Puccinia graminis f. sp. tritici) for the last 70 years in the United States and Canada. To identify signaling components of protein product RPG1, we employed a mutagenesis approach. Using this approach, six mutants exhibiting susceptibility to Puccinia graminis f. sp. tritici races MCCF and HKHJ were identified in the gamma irradiated M population of resistant cultivar Morex, which carries Rpg1 on chromosome 7H. The mutants retained a functional Rpg1 gene and an apparently functional protein, suggesting that the mutated genes were required for downstream or upstream signaling. Selected mutants were non-allelic, hence each mutant represents a unique gene. Low and high-resolution genetic mapping of the rpr2 mutant identified chromosome 6H (bin 6) as the location of the mutated gene. The target region was reduced to 0.6 cM and gene content analyzed. Based on the published barley genomic sequence, the target region contains approximately 157 genes, including a set that encodes putative leucine-rich receptor-like protein kinases, which may be strong candidates for the gene of interest. Overall, this study presents a strong platform for future map-based cloning of genes identified in this mutant screen. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Plant Protection & Pathology is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Barley yellow dwarf viruses (BYDVs) are responsible for the disease barley yellow dwarf (BYD) and affect many cereals including oat (Avena sativa L.). Until recently, the molecular marker technology in oat has not allowed for many marker-trait association studies to determine the genetic mechanisms for tolerance. A genome-wide association study (GWAS) was performed on 428 spring oat lines using a recently developed high-density oat single nucleotide polymorphism (SNP) array as well as a SNP-based consensus map. Marker-trait associations were performed using a Q-K mixed model approach to control for population structure and relatedness. Six significant SNP-trait associations representing two QTL were found on chromosomes 3C (Mrg17) and 18D (Mrg04). This is the first report of BYDV tolerance QTL on chromosome 3C (Mrg17) and 18D (Mrg04). Haplotypes using the two QTL were evaluated and distinct classes for tolerance were identified based on the number of favorable alleles. A large number of lines carrying both favorable alleles were observed in the panel. [ABSTRACT FROM AUTHOR]

Background: The Avrk1 and Avra10 avirulence (AVR) genes encode effectors that increase the pathogenicity of the fungus Blumeria graminis f.sp. hordei (Bgh), the powdery mildew pathogen, in susceptible barley plants. In resistant barley, MLK1 and MLA10 resistance proteins recognize the presence of AVRK1 and AVRA10, eliciting the hypersensitive response typical of gene for gene interactions. Avrk1 and Avra10 have more than 1350 homologues in Bgh genome, forming the EKA (Effectors homologous to Avrk1 and Avra10) gene family. Results: We tested the hypothesis that the EKA family originated from degenerate copies of Class I LINE retrotransposons by analysing the EKA family in the genome of Bgh isolate DH14 with bioinformatic tools specially developed for the analysis of Transposable Elements (TE) in genomes. The Class I LINE retrotransposon copies homologous to Avrk1 and Avra10 represent 6.5 % of the Bgh annotated genome and, among them, we identified 293 AVR/effector candidate genes. We also experimentally identified peptides that indicated the translation of several predicted proteins from EKA family members, which had higher relative abundance in haustoria than in hyphae. Conclusions: Our analyses indicate that Avrk1 and Avra10 have evolved from part of the ORF1 gene of Class I LINE retrotransposons. The co-option of Avra10 and Avrk1 as effectors from truncated copies of retrotransposons explains the huge number of homologues in Bgh genome that could act as dynamic reservoirs from which new effector genes may evolve. These data provide further evidence for recruitment of retrotransposons in the evolution of new biological functions. [ABSTRACT FROM AUTHOR]

one of the most important factors affecting genomic prediction accuracy appears to be training population (Tp) composition. The objective of this study was to evaluate the effect of genomic relationship on genomic prediction accuracy and determine if adding increasingly unrelated individuals to a Tp can reduce prediction accuracy. To accomplish this, a population of barley (Hordeum vulgare L.) lines from the University of Minnesota (lines denoted as MN) and North Dakota State University (lines denoted as ND) breeding programs were used for model training. predictions were validated using two independent sets of progenies derived from MN × MN crosses and ND × ND crosses. predictive ability sharply decreased with decreasing relationship between the Tp and validation population (Vp). More importantly, it was observed that adding increasingly unrelated individuals to the Tp can actually reduce predictive ability compared with smaller Tps consisting of highly related individuals only. reported results are possibly conditional on the relatively low marker density (342 single nucleotide polymorphisms [SNps]) used. Nevertheless, these findings suggest plant breeding programs desiring to use genomic selection could benefit from focusing on good phenotyping of smaller Tps closely related to the selection candidates rather than developing large and diverse Tps. [ABSTRACT FROM AUTHOR]

This study was conducted to determine the population density of khapra beetle, Trogoderma granarium Everts, on grains and spikes of wheat (Adnania variety) and barely (barley hybrid, Forat x Baraka; black barley, Al- Jazera variety and White barley, Badea variety) under natural room storage condition for five months period (from July till November, 2012), in addition the loss in weight due to the infestation were evaluated. The results indicated that, for each sample of 25 gm, the average total number of all stages of insect recorded on grains at the end of storage period were 927.50 individuals and the total weight loss due to infestation were 25.68% while on spikes there were 15.42 individuals and weight losses of 0.24%. The highest mean number of all stages was 1045.50 individuals with highest weight losses of 24.6% in wheat grains and the lowest number was 8.70 individual with lowest weight losses of 0.64% in white barley grains. The interaction between the kind of storage, in grains or spikes, with the kind of grains have considerably significant effect on the mean number of different stages of insect as well as the mean weight loss. [ABSTRACT FROM AUTHOR]

C1A plant cysteine proteases are synthesized as pre-pro-enzymes that need to be processed to become active by the pro-peptide claves off from its cognate enzyme. These pro-sequences play multifunctional roles including the capacity to specifically inhibit their own as well as other C1A protease activities from diverse origin. In this study, it is analysed the potential role of C1A pro-regions from barley as regulators of cysteine proteases in target phytophagous arthropods (coleopteran and acari). The in vitro inhibitory action of these pro-sequences, purified as recombinant proteins, is demonstrated. Moreover, transgenic Arabidopsis plants expressing different fragments of HvPap-1 barley gene containing the pro-peptide sequence were generated and the acaricide function was confirmed by bioassays conducted with the two-spotted spider mite Tetranychus urticae. Feeding trials resulted in a significant reduction of leaf damage in the transgenic lines expressing the pro-peptide in comparison to non-transformed control and strongly correlated with an increase in mite mortality. Additionally, the analysis of the expression levels of a selection of potential mite targets (proteases and protease inhibitors) revealed a mite strategy to counteract the inhibitory activity produced by the C1A barley pro-prodomain. These findings demonstrate that pro-peptides can control mite pests and could be applied as defence proteins in biotechnological systems. [ABSTRACT FROM AUTHOR]

Key message: Multi-environment multi-QTL mixed models were used in a GWAS context to identify QTL for disease resistance. The use of mega-environments aided the interpretation of environment-specific and general QTL. Abstract: Diseases represent a major constraint for barley ( Hordeum vulgare L.) production in Latin America. Spot blotch (caused by Cochliobolus sativus), stripe rust (caused by Puccinia striiformis f.sp. hordei) and leaf rust (caused by Puccinia hordei) are three of the most important diseases that affect the crop in the region. Since fungicide application is not an economically or environmentally sound solution, the development of durably resistant varieties is a priority for breeding programs. Therefore, new resistance sources are needed. The objective of this work was to detect genomic regions associated with field level plant resistance to spot blotch, stripe rust, and leaf rust in Latin American germplasm. Disease severities measured in multi-environment trials across the Americas and 1,096 SNPs in a population of 360 genotypes were used to identify genomic regions associated with disease resistance. Optimized experimental design and spatial modeling were used in each trial to estimate genotypic means. Genome-Wide Association Mapping (GWAS) in each environment was used to detect Quantitative Trait Loci (QTL). All significant environment-specific QTL were subsequently included in a multi-environment-multi-QTL (MEMQ) model. Geographical origin and inflorescence type were the main determinants of population structure. Spot blotch severity was low to intermediate while leaf and stripe rust severity was high in all environments. Mega-environments were defined by locations for spot blotch and leaf rust. Significant marker-trait associations for spot blotch (9 QTL), leaf (6 QTL) and stripe rust (7 QTL) and both global and environment-specific QTL were detected that will be useful for future breeding efforts. [ABSTRACT FROM AUTHOR]

We report on a new adult plant resistance (APR) gene Rph23 conferring resistance to leaf rust in barley. The gene was identified and characterized from a doubled haploid population derived from an intercross between the Australian barley varieties Yerong (Y) and Franklin (F). Genetic analysis of adult plant field leaf rust scores of the Y/F population collected over three successive years indicated involvement of two highly additive genes controlling APR, one of which was named Rph23. The gene was mapped to chromosome 7HS positioned at a genetic distance 36.6 cM. Rph23 is closely linked to marker Ebmac0603, which is flanked by markers bPb-8660 and bPb-9601 with linkage distances of 0.8 and 5.1 cM, respectively. A PCR-based marker was optimized for marker-assisted selection of Rph23, and on the basis of this marker, the gene was postulated as being common in Australian and global barley germplasm. Pedigree and molecular marker analyses indicated that the six-rowed black Russian landrace 'LV-Taganrog' is the likely origin of Rph23. [ABSTRACT FROM AUTHOR]

Barley spot blotch (SB) is a frequent foliar disease of the brewing barley crop in southern Brazil. At present, there are few reports regarding the efficacy of fungicide spray programs in relation to the severity of SB damage to barley crop yield. The goals of this study were as follows: 1) to determine the crop growth stage at which severity of SB was most strongly related to grain yield (GY), thousand kernel weight (TKW), and granulometry (G) damage in brewing barley and 2) to evaluate the efficacy of fungicides in controlling SB and the effect of fungicide application timing on disease intensity and yield. The experiments were performed using the BRS Cauê barley cultivar at Muitos Capões municipality, Rio Grande do Sul State, southern Brazil, during the 2009 and 2010 growing seasons. The experiments involved a randomized complete block design with five treatments and four replicates. The treatments varied by the number of fungicide applications. The control received no fungicide application. SB severity assessments were performed at the following growth stages: main stem and one tiller developed, main stem and four tillers developed, swelling 2nd node detectable, flag leaf ligule just visible, full boot, and 50% of spikes visible. SB severity data were integrated as a function of time to determine the area under the disease progress curve (AUDPC). SB resulted in damage of up to 49.2% and 34.6% in GY, 19.9% and 19.7% in TKW, and 26.0% and 11.2% in G in the 2009 and 2010 growing seasons, respectively. A frequency of three and four foliar fungicide applications controlled 70.1% and 78.3% of SB in the 2009 growing season and 85.8% and 88.6% in the 2010 growing season, respectively. GY and SB severity showed a significant negative relationship in both the 2009 and 2010 growing seasons and at all growth stages evaluated. The greatest GY damage related to SB severity occurred at the final growth stages at full boot and 50% of spikes visible. There was a significant negative relationship between AUDPC and GY, with damage coefficients of 17.19 and 22.94 in the 2009 and 2010 growing seasons, respectively. There was a positive net return on barley GY, TKW, and G when four fungicide applications were used for SB control. [ABSTRACT FROM AUTHOR]

Net blotch (Pyrenophora teres) is one of the most devastating diseases of barley (Hordeum vulgare L.) worldwide. Identification of diagnostic molecular markers associated with genes and quantitative trait loci (QTL) for net blotch resistance will facilitate pyramiding of independent genes. Linkage mapping was used to identify chromosomal locations of the independent, dominant genes conditioning net blotch resistance in the winter barley 'Nomini' (PI 566929) and spring barley CIho 2291. The F2 populations of 238 and 193 individuals, derived from crosses between the susceptible spring barley parent 'Hector' (CIho 15514) and the resistant parents Nomini and CIho 2291, respectively, were used to map the genes governing resistance in the resistant parents. The dominant gene governing resistance in Nomini, temporarily designated Rpt-Nomini, was mapped to a 9.2-cM region of barley chromosome 6H between the flanking microsatellite markers Bmag0344a (r² = 0.7) and Bmag0103a (r² = 0.9), which were 6.8 and 2.4 cM away from Rpt-Nomini, respectively. The dominant gene governing resistance in CIho 2291, temporarily designated Rpt-CIho2291, was mapped to a 34.3-cM interval on the distal region of barley chromosome 6H between the flanking microsatellite markers Bmag0173 (r² = 0.65) and Bmag0500 (r² = 0.26), which were 9.9 and 24.4 cM away from Rpt-CIho2291, respectively. Identification of the chromosomal location of Rpt-Nomini and Rpt-CIho2291 will facilitate efforts in pyramiding multiple genes for net blotch resistance. [ABSTRACT FROM AUTHOR]

Cereal yellow dwarf virus (CYDV-RPV) causes a serious viral disease affecting small grain crops around the world. In the United States, it frequently is present in California where it causes significant yield losses, and when infections start early in development, plant death. CYDV is transmitted by aphids, and it has been a major impediment to developing malting barley in California. To identify chromosome locations associated with tolerance/resistance to CYDV, a segregating population of 184 recombinant inbred lines (RIL) from a cross of the California-adapted malting barley line Butta 12 with the CYDVtolerant Madre Selva was used to construct a genetic map including 180 polymorphic markers mapping to 170 unique loci. Tolerance to CYDV was evaluated in replicated experiments where plants were challenged by aphid mediated inoculation with the isolate CYDV-RPV in a controlled environment. Quantitative trait loci (QTL) analysis revealed the presence of two major QTL for CYDV tolerance from Madre Selva on chromosomes 2H (Qcyd.MaBu-1) and 7H (Qcyd.MaBu- 2), and 4 minor QTL from Butta 12 on chromosomes 3H, 4H, and 2H. This paper discusses the contribution of each QTL and its potential value to improve barley tolerance to CYDV. [ABSTRACT FROM AUTHOR]

Russian wheat aphid [RWA; Diuraphis noxia (Mordvilko)] is a worldwide insect pest of barley (Hordeum vulgare L.), causing crop losses each year. Previously identified resistant barley lines do not show variable reactions to the eight United States RWA biotypes identified by wheat reactions. However, additional RWA isolates have been identified outside the United States. The objective of this research was to determine whether additional RWA biotypes that impact resistance in barley exist and whether resistance to these biotypes is present in the resistant barley germplasm and cultivars that have been developed by the USDA-ARS. A total of 166 barley lines were rated for chlorosis and leaf rolling in response to infestation with RWA United States' biotype 1 and to individual isolates from Hungary, Chile, Mexico, and Iran. Each barley line was genotyped for 5912 single nucleotide polymorphism (SNP) markers, and the combined data were used for association mapping of loci associated with resistance to each RWA isolate. A total of 40 loci were associated with resistance to the five RWA isolates. Biotype differences were evident, with only 23 lines showing resistance to all five biotypes. Loci with large effects on mean chlorosis and rolling differences were found for resistance to biotypes from the United States, Hungary, and Chile, while the loci for resistance to biotypes from Mexico and Iran had small effects on these traits, which may pose problems for developing resistant germplasm. The 23 lines resistant to all biotypes included 10 unadapted germplasm accessions and 13 improved germplasm lines and provide useful germplasm for developing new barley cultivars with resistance to multiple RWA biotypes. [ABSTRACT FROM AUTHOR]

Key message: This study demonstrates for the first time that resistance to different root lesion nematodes ( P. neglectus and P. penetrans ) is controlled by a common QTL. A major resistance QTL ( Rlnnp6H ) has been mapped to chromosome 6H using two independent barley populations. Abstract: Root lesion nematodes ( Pratylenchus spp.) are important pests in cereal production worldwide. We selected two doubled haploid populations of barley (Igri × Franka and Uschi × HHOR 3073) and infected them with Pratylenchus penetrans and Pratylenchus neglectus. Nematode multiplication rates were measured 7 or 10 weeks after infection. In both populations, continuous phenotypic variations for nematode multiplication rates were detected indicating a quantitative inheritance of resistance. In the Igri × Franka population, four P. penetrans resistance QTLs were mapped with 857 molecular markers on four linkage groups (2H, 5H, 6H and 7H). In the Uschi × HHOR 3073 population, eleven resistance QTLs ( P. penetrans and P. neglectus) were mapped with 646 molecular markers on linkage groups 1H, 3H, 4H, 5H, 6H and 7H. A major resistance QTL named Rlnnp6H (LOD score 6.42-11.19) with a large phenotypic effect (27.5-36.6 %) for both pests was mapped in both populations to chromosome 6H. Another resistance QTL for both pests was mapped on linkage group 5H (Igri × Franka population). These data provide first evidence for common resistance mechanisms against different root lesion nematode species. The molecular markers are a powerful tool for the selection of resistant barley lines among segregating populations because resistance tests are time consuming and laborious. [ABSTRACT FROM AUTHOR]

Barley yellow dwarf disease (BYD) is transmitted by aphids and is caused by different strains of Barley yellow dwarf virus (BYDV) and Cereal yellow dwarf virus (CYDV). Economically it is one of the most important diseases of cereals worldwide. Besides chemical control of the vector, growing of tolerant/resistant cultivars is an effective way of protecting crops against BYD. The Ryd3 gene in barley ( Hordeum vulgare L.) confers tolerance to BYDV-PAV and BYDV-MAV and the locus was previously mapped on the short arm of barley chromosome 6H near the centromere. We applied a strategy for high-resolution mapping and marker saturation at the Ryd3 locus by exploiting recent genomic tools available in barley. In a population of 3,210 F2 plants, 14 tightly linked markers were identified, including 10 that co-segregated with Ryd3. The centromeric region where Ryd3 is located suffers suppressed recombination or reduced recombination rate, suggesting potential problems in achieving (1) map-based cloning of Ryd3 and (2) marker selection of the resistance in breeding programmes without the introduction of undesirable traits via linkage drag. [ABSTRACT FROM AUTHOR]

Abstract: Drop behaviour during impact affects retention. Increasing adhesion is usually seen as an objective when applying crop protection products, while bouncing and shattering are seen as detrimental to spray retention. However, observation of drop impacts on barley (Hordeum vulgare L.) using high speed shadowgraphy shows that bouncing and fragmentation can occur in Cassie–Baxter as well as in Wenzel wetting regimes. In this last regime, a part of the drop may remain stuck on the surface, contributing to retention. Using simultaneous measurements of drop impacts with high speed imaging and of retention with fluorophotometry for spray mixtures on excised barley leaves using a Teejet 11003 nozzle at 0.2 MPa, it was observed that about 50% of the drops that fragmented in the Wenzel state remain on the horizontal leaf. Depending on the spray mixture, these impact outcomes accounted for 28–46% of retention, the higher contribution being correlated with bigger VMD (Volume Median Diameter). This contribution is not negligible and should be considered when modelling spray retention processes. [Copyright &y& Elsevier]

Leaf rust of barley, caused by Puccinia hordei, occurs in all barley-growing regions of Australia causing significant yield losses under epidemic conditions. The development and use of resistant cultivars are the most economical and environmentally sustainable method to control leaf rust which in turn relies on ongoing efforts to identify and characterize new sources of resistance. The aim of this study was to postulate known genes and/or identify new sources of resistance to P. hordei. Fifty-two genotypes were assessed at the seedling and adult plant growth stages. On the basis of multipathotype tests, 39 genotypes lacked detectable seedling resistance, and nine were postulated to carry the genes Rph2, Rph4, Rph12 and Rph19 singly. Four genotypes carried uncharacterized seedling resistance; however, the gene(s) present in each were ineffective to at least one of the pathotypes used. Field tests at the adult plant growth stage revealed the presence of adult plant resistance ( APR) in 12 genotypes. Tests of allelism and marker analysis indicated that resistance genes present in these genotypes were independent of the APR gene Rph20. [ABSTRACT FROM AUTHOR]

In central Europe, winter barley is infected by a broader spectrum of pathogens than spring barley. However, the dominant disease on susceptible cultivars is powdery mildew. The objective of this contribution was to postulate resistance genes in cultivars registered in the Czech Republic and Slovakia from 1993 to 2010 using a set of 40 isolates of the barley powdery mildew pathogen. Seedlings of 42 European cultivars were tested, and 15 known resistance genes were postulated namely, Mla6, Mla7, Mla12, Mla13, MlaRu4, Mlg, Mlh, MlLa, Mlra, Ml( Ch), Ml( Dr2), Ml( IM9), Ml( Lo), Ml( Ru2) and Ml( St). Two unknown resistances were detected, one in cultivars Gilberta, Mirko and Polana, and another in Ricus. Three cultivars ( Campanile, Carrero and Mirko) were heterogeneous for mildew response. The most frequent genes were Mlra and Mlh, which were found in 25 and 14 cultivars, respectively. Genes located at the Mla locus were present in 14 cultivars; 11 of these cultivars carried Mla6. No resistance gene was detected in Hanna. Previously unknown resistances will be further characterized. [ABSTRACT FROM AUTHOR]

‘Dahye’, a new covered cultivar derived from the crosses between ‘Suwon318' and‘Suwon311' developed at the Honam Agricultural Research Institute (HARI), NICS, RDA in 2007. The initial crossing was made in 1996 and an elite line, ‘SB964008-B-B-B-92' was selected from under yield trial test in 2004. It was designed as ‘Iksan409' and showed a high yield and had good quality in the regional yield trials (RYT) from 2005 to 2007. It was released with the name of ‘Dahye’.‘Dahye’had a rate Ⅲ growth habit, green leaf and stem, compact spike and long rough awns. The heading date was April 29 in upland and April 20 in paddy field, which was 2 and 5 days earlier than that of check cultivar,‘Olbori', respectively. It had 88 cm of culm length, 4.2 cm of spike length and 666 spikes per m2, 52 grains per spike, 35.6 g of 1,000-grain weight and 702 g of test weight. It showed stronger winter hardiness and higher resistance to barley yellow mosaic virus (BaYMV) than those of check cultivar. It had similar protein content with check cultivar and higher whiteness and diastatic power (DP) than those of Olbori. The average yield of the pearled grain in the regional yield trial (RYT) was 4.00 ton ha-1 in upland and 4.11 ton ha-1 in paddy field. This cultivar would be suitable for the area that the daily minimum mean temperature is above -8℃ in January in Korean peninsula. [ABSTRACT FROM AUTHOR]

BRS Savanna, a cross between V. Morales x IF200113, is a spring andan early-maturing six-rowed barley, widely adapted to irrigated areas of the savanna, in Central Brazil. It presents production stability and the industrial quality, grain yield and lodging resistance are high. It is suitable for cultivation in the states of GO, MG and DF [ABSTRACT FROM AUTHOR]

A large number of resistances to powdery mildew (Blumeria graminis f.sp. hordei) and their combinations are known in barley (Hordeum vulgare L.). A similarity of resistance spectra between cultivars carrying the resistance Bw, designated for the winter barley cultivar Borwina, and the near-isogenic spring barley line P15, which carries the resistance Ru2, derived from the landrace Rupee, was found. The objective of this study was to test the difference between resistances Bw and Ru2. Six cultivars were tested, four with Bw and two with Ru2. Testing with 40 isolates showed identical reaction spectra between both groups. Testing of the cultivar Kompolti 4 (Bw) and line P15 (Ru2) with 300 isolates confirmed this result. Thus, the resistances currently designated Bw and Ru2 can be regarded as identical, and are determined by the gene Ml(Ru2). Both Bw and Ru2 should be designated by the earlier code, Ru2. [ABSTRACT FROM AUTHOR]

This work aimed to determine patterns of pathogenicity in Pyrenophora teres f. teres and to identify potentially effective resistance sources that could be used as breeding material to control net blotch in Tunisia. Extensive pathogenic variability was detected in 85 isolates of P. teres causing net blotch of barley in Tunisia. Based on unweighted pair-group method with arithmetic averaging clustering and mean disease rating scores, three distinct virulence groups were identified. The isolates were classified into 23 pathotypes. Pathogenic variability within the groups was higher than that between the groups, a finding that can guide a rational choice of isolates for screening lines as part of a breeding program. Conversely, studying the relationship between geographic and pathotypic structure allowed us to detect a significant isolation by distance pattern, suggesting a regular and gradual dispersal of the pathogen over this spatial scale. Using specific resistance prop-erties of individual barley genotypes as virulence markers, all the dif-ferential barley genotypes were shown to be distinct, and no single source of resistance was totally effective against all isolates. [ABSTRACT FROM AUTHOR]

Fusarium crown rot (FCR) is a major disease of wheat and barley, and stem-base browning has been routinely used to measure resistance. Compared with barley ( Hordeum vulgare L.), bread wheat ( Triticum aestivum L.) shows less severe FCR stem-base browning symptoms (indicative of greater resistance or tolerance) but suffers higher yield loss (indicative of greater susceptibility), whereas durum wheat ( T. durum Desf.) shows similar FCR severity but suffers much worse yield loss. To understand these differences, fungal biomass in bread and durum wheats and barley was estimated by real-time quantitative PCR at different stages of FCR disease development. Similar to a previous report on bread wheat infection by Fusarium graminearum, FCR infection caused by Fusarium pseudograminearum also showed 'three distinct phases' in each of the three crop species analysed. During all stages of FCR disease development, barley varieties invariably displayed earlier and faster fungal accumulation compared with either bread or durum wheat. Although suffering much greater yield loss than barley, durum wheat appears to accumulate significantly lower levels of F. pseodugraminearum during infection. These results demonstrate that bread wheat varieties are more resistant to FCR infection and pathogen accumulation than barley varieties, and the less yield loss of the latter is likely due to its better tolerance to this disease. If also existing among different sources of resistance within a given species, these different features of disease resistance and tolerance could be exploited to minimize yield loss of new varieties. [ABSTRACT FROM AUTHOR]

Yellow rust caused by Puccinia striiformis f. sp. hordei is an important disease of barley (Hordeum vulgare L.) in some parts of the world. We compared the effectiveness of different types of resistance in field plots at Ardabil Agricultural Research Station (Iran) during 2010–2011. Yield components along with slow rusting parameters including final rust severity (FRS), apparent infection rate (r), relative area under disease progress curve (rAUDPC) and coefficient of infection (CI) were evaluated for 25 barley cultivars. In all, two barley cultivars with race-specific resistance, 19 cultivars with different levels of slow rusting resistance and four susceptible cultivars were included in two experiments with and without fungicide protection under high disease pressure. Barley cultivars with slow rusting resistance displayed a range of severity responses indicating phenotypic diversity. Mean thousand kernels weight (TKW) losses for susceptible, race-specific and slow rusting genotypes were 31, 3 and 12%, respectively, and mean kernels per spike (KPS) losses for susceptible, race-specific and slow rusting genotypes were 19, 0.2 and 8%, respectively. Correlation coefficient of mean TKW and KPS losses with epidemiological parameters; rAUDPC, r, CI and FRS were highly significant. Slow rusting cultivars with low values of different parameters as well as genotypes with low yield component losses despite moderate disease levels were identified. Such genotypes can be used for breeding barely genotypes with high levels of resistance and negligible yield losses. [ABSTRACT FROM PUBLISHER]

In 2006-2010, resistance to the powdery mildew pathogen was studied in 277 spring barley cultivars. They were represented by 54 cultivars in Czech official variety trials, of which 42 were foreign, and 223 cultivars in variety trials conducted by domestic breeding companies in that period. Sixty-eight domestic cultivars (28.8%) exhibited heterogeneity in the examined trait, i.e. they were composed of lines with different resistances to powdery mildew. Thirteen known resistances were identified (Ab, Ar, HH, La, Ly, Mlo, Ri, Ro, Ru, Sp, St, Tu2 and We). The most frequent resistance was Mlo detected in 160 homogeneous cultivars (= 76.6%). The newly described resistance Ro was found in 13 cultivars. Frequency of other resistances was low (maximally 2.4%). Unknown resistances were found in 16 cultivars, in five of which they were effective to all used pathotypes of the pathogen. Research on cultivars possessing unknown resistances and registered heterogeneous cultivars continues. [ABSTRACT FROM AUTHOR]

Genomic regions influencing resistance to powdery mildew [Blumeria graminis (DC.) E.O. Speer f. sp. hordei Em. Marchal] were detected in a doubled haploid (DH) barley (Hordeum vulgare L.) population derived from a cross between the breeding line ND24260 and cultivar Flagship when evaluated across four field environments in Australia and Uruguay. Significant quantitative trait loci (QTL) for resistance to B. graminis were detected on six of the seven chromosomes (1H, 2H, 3H, 4H, 5H, and 7H). A QTL with large effect donated by ND24260 mapped to the short arm of chromosome 1H (1HS) conferring near immunity to B. graminis in Australia but was ineffective in Uruguay. Three QTL donated by Flagship contributed partial resistance to B. graminis and were detected in at least two environments. These QTL were mapped to chromosomes 3H, 4H, and 5H (5HS) accounting for up to 18.6, 3.4, and 8.8% phenotypic variation, respectively. The 5HS QTL contributed partial resistance to B. graminis in all field environments in both Australia and Uruguay and aligned with the genomic region of Rph2O, a gene conferring adult plant resistance (APR) to leaf rust (Puccinia hordei Otth), which is found in some cultivars having `Vada' or `Emir' in their parentage. Selection for favorable marker haplotypes within the 3H, 4H, and 5H QTL regions can be performed even in the presence of single (major) gene resistance. Pyramiding such QTL may provide an effective and potentially durable form of resistance to B. graminis. [ABSTRACT FROM AUTHOR]

The responses of 95 barley lines and cultivars to spot form of net blotch (SFNB) caused by Pyrenophora teres f. maculata were analyzed as seedlings and adults in Australia and Canada. Cluster analyses revealed complex reaction responses. Only 2 lines (Esperance Orge 289 and TR3189) were resistant to all isolates at the seedling stage, whereas 15 lines and cultivars (81-82/033, Arimont, BYDV-018, CBSS97M00855T-B2-M1-Y1-M2-Y-IM-0Y, CI9776, Keel, Sloop, Torrens, TR326, VB0111, Yarra, VB0229, WI-2477, WI2553, and Wisconsin Pedigree) were resistant toward the two Canadian isolates and mixture of Australian isolates at the adult stages. In Australian field experiments, the effectiveness of SFNB resistance in three barley cultivars (Barque, Cowabbie, and Schooner) and one breeding line (VB9104) with a different source of resistance was tested. Barque, which possessed a resistance gene that provided complete resistance to SFNB, was the most effective and showed no effect on grain yield or quality in the presence of inoculum. Generally, cultivars with seedling or adult resistance had less disease and better grain quality than the susceptible control, Dash, but they were not as effective as Barque. A preliminary differential set of 19 barley lines and cultivars for P. teres f. maculata is proposed. [ABSTRACT FROM AUTHOR]

Abstract: Cereal farming is moving rapidly towards reduced tillage, with over 100 million ha of land currently tilled using minimum tillage implements. This study reports five years of data from a field experiment investigating the response of different barley cultivars and mixtures to soil tillage practice and nitrogen fertiliser levels. Five tillage treatments were established that imposed different amounts of soil disturbance: (T1) zero tillage, (T2) minimum tillage to 7cm depth and ploughed treatments followed by power harrowing consisting of (T3) conventional plough to 20cm depth, (T4) plough to 20cm followed by compaction by wheeling the entire plot with a tractor fitted with 8.8 Mg total load and (T5) deep plough to 40cm depth, all on the same site each year. Four winter barley cultivars (Sumo, Fanfare, Pastoral and Pipkin) were selected based on contrasting rooting characteristics, disease resistance and yield sensitivity. They were planted in plots as monocultures and as all 2-, 3- and 4-component mixtures thereof. Significant differences in soil physical properties and carbon content were observed over the five years of the study. Grain yield varied by 13% between tillage treatments, with conventional and deep plough conditions generally the highest yielding and zero tillage the lowest. Sumo gave the highest yield overall under deep plough conditions, whereas Pipkin was the best cultivar under conventional and zero tillage conditions. Rhynchosporium was the most common disease and the mixture gave decreased infection in all years and tillage conditions. Complex mixtures gave around 32% less disease than the simple mixtures. There was an overall differential cultivar response to soil tillage conditions that was buffered by cultivar mixtures. Mixtures offered benefits in both yield response and disease control under all soil tillage conditions. [Copyright &y& Elsevier]

SUMMARY The receptor-like protein kinases (RLKs) constitute a large and diverse group of proteins controlling numerous plant physiological processes, including development, hormone perception and stress responses. The cysteine-rich RLKs (CRKs) represent a prominent subfamily of transmembrane-anchored RLKs. We have identified a putative barley ( Hordeum vulgare) CRK gene family member, designated HvCRK1. The mature putative protein comprises 645 amino acids, and includes a putative receptor domain containing two characteristic 'domain 26 of unknown function' (duf26) domains in the N-terminal region, followed by a rather short 17-amino-acid transmembrane domain, which includes an AAA motif, two features characteristic of endoplasmic reticulum (ER)-targeted proteins and, finally, a characteristic putative protein kinase domain in the C-terminus. The HvCRK1 transcript was isolated from leaves inoculated with the biotrophic fungal pathogen Blumeria graminis f.sp. hordei ( Bgh). HvCRK1 transcripts were observed to accumulate transiently following Bgh inoculation of susceptible barley. Transient silencing of HvCRK1 expression in bombarded epidermal cells led to enhanced resistance to Bgh, but did not affect R-gene-mediated resistance. Silencing of HvCRK1 phenocopied the effective penetration resistance found in mlo-resistant barley plants, and the possible link between HvCRK1 and MLO was substantiated by the fact that HvCRK1 induction on Bgh inoculation was dependent on Mlo. Finally, using both experimental and in silico approaches, we demonstrated that HvCRK1 localizes to the ER of barley cells. The negative effect on basal resistance against Bgh and the functional aspects of MLO- and ER-localized HvCRK1 signalling on Bgh inoculation are discussed. [ABSTRACT FROM AUTHOR]

Fusarium head blight (FHB), caused by the fungal plant pathogen Fusarium graminearum (teleomorph Gibberella zeae), is a devastating disease of barley (Hordeum vulgare) in the United States. Recent epidemics of FHB in the mid-Atlantic region have underscored the need to develop new commercial varieties of barley that are resistant to FHB and restrict accumulation of the mycotoxin deoxynivalenol (DON). FHB incidence, FHB index, and DON levels of Virginia hulled and hulless barley genotypes were evaluated over five years (2006 to 2010) in FHB nurseries in Virginia. FHB incidence ranged from 22.5% (2010) to 80.1% (2008), and mean DON levels ranged from 0.5 ± 0.4 (2008) to 2.4 ± 2.1 ppm (2010). Barley genotype played a significant role in determining FHB resistance in 2006 to 2009. DON levels were significantly different among barley genotypes in 2007, 2008, and 2009. FHB incidence was positively correlated with FHB index in all 5 years studied. In 2006 and 2010, FHB incidence and index were positively correlated with DON. Early spike emergence resulted in higher FHB incidence and index in 2007, 2008, and 2010. This preliminary work has identified some promising hulled and hulless barley genotypes for targeted breeding and commercialization efforts in FHB nurseries in the future; 'Eve' (hulless) and 'Thoroughbred' (hulled) ranked among the most FHB resistant genotypes. [ABSTRACT FROM AUTHOR]

Abstract: Rusts and powdery mildews employ different strategies to suppress defense during penetration. We observed that a compatible interaction of barley-Puccinia hordei induced increased penetration resistance to a challenge infection by powdery mildew. This induced resistance is local and its level is not determined by the virulence spectrum of the challenger isolate. Our data suggest that the inducer effect is due to rust-stoma communication during penetration, to the presence of the rust hyphae in the apoplast, or to penetration resistance mounted by the rust attacked mesophyll cells. We hypothesized that the rust “primes” the basal defense prior to the mildew infection. [Copyright &y& Elsevier]

Trichothecenes are sesquiterpene mycotoxins produced by Fusarium spp. and cause serious health problems in humans and animals. A trichothecene, deoxynivalenol (DON), produced by Fusarium graminearum, the causal agent of fusarium head blight (FHB) in wheat, barley, and triticale, has been reported as a virulence factor. In this study, 10 selected resistance-related (RR) endogenous metabolites, previously demonstrated to inhibit mycelial biomass, were further evaluated for their efficiency in the inhibition of trichothecene biosynthesis by F. graminearum. These RR metabolites belong to phenolic, flavonoid and fatty acid chemical groups. Basal liquid medium inoculated with F. graminearum, and amended with or without RR metabolites at their LD50 molar concentrations for biomass inhibition, were incubated for 5 days. Dry fungal biomass was determined. The trichothecenes were extracted from the spent media and analyzed using LC–ESI–LTQ–Orbitrap. Trichothecene production was completely inhibited by lauric, p-coumaric, sinapic and ferulic acids, naringenin, quercetin and methyl jasmonate at LD50 molar concentrations. Trichothecene biosynthesis inhibition, relative to control, was partial with capric, quinic and caffeic acid. The cumulative effects of these RR metabolites, as both mycelial biomass inhibitors and trichothecene inhibitors, and their potential application as resistance biomarker metabolites to screen wheat and barley are discussed. [ABSTRACT FROM AUTHOR]