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This study aims at monitoring the dynamics of the occurrence and evolution of the attack of some pathogens to barley, among which we mention: mildew (Blummeria graminis f.sp. hordei), leaf stripe (Pyrenophora graminea) and barley's rust (Puccinia hordei). Also, the influence of applying these fungicides on the harvest, as well as of the number of treatments/ha as compared to the untreated control variant, has been monitored. For this study, an experiment with 6 treatment variants was created, being used the following phytosanitary products: EVALIA (azoxystrobin 250 g/l), RETENGO (200 g/l pyraclostrobin) and NATIVO PRO 325 SL (prothioconazole 175 g/l + trifloxystrobin 150 g/l). The treatment variants were the following: V1-RETENGO 0.8 l/ha, 1 treatment was applied on 13th April + 1 treatment on 17th May; V2 - EVALIA 0.75 l/ha, 1 treatment was applied on 13th April +1 treatment on 17th May; V3-NATIVO PRO 0.6l/ha, 1 treatment was applied on 13th April + 1 treatment on 17th May; V4- RETENGO 0.8 l/ha, 1 treatment was applied on 22nd May, V5- EVALIA 1.0 l/ha, 1 treatment was applied on 22nd May, V6- NATIVO 0.7 l/ha, 1 treatment was applied on 22nd May, V7 - Untreated Control Variant. The experiment was placed in Latin square, the 7 variants being placed in 7 repetitions. The year 2022 was a year where the spring and the beginning of summer were very dry, totally unfavorable to pathogen attacks. The experiment was not irrigated. Among the pathogens monitored, very weak attacks by the fungus Pyrenophora graminea, which produces, in barley, the disease known as leaf stripe, were observed. This led to very uniform yields in the variants studied. Basically, no significant yield differences occurred in the climate conditions of 2022 between the untreated control variant and the variants that were treated with fungicides. The variant's yields were: V1 - 5,276 to/ha, V2 - 5,292 to/ha, V3 - 5,451 to/ha, V4 - 5,184 to/ha, V5 - 5,601 to/ha, V6 - 5,585 to/ha and V7 - 5,508 to/ha. [ABSTRACT FROM AUTHOR]

Feed grains are prone to fungal infections during growth, harvesting, and storage. Corns such as wheat and barley may be contaminated with mycotoxins leading to acute and chronic animal health exposure. The objective of this study was to obtain an information on the levels of ochratoxin A (OTA) and zearalenone (ZEA) in wheat (n=26) and barley (n=21) samples intended for feeding to farm animals. The samples were collected from different regions of Bulgaria in 2017 harvest and analyzed by using Enzyme-linked immunosorbent assay (ELISA). The results showed that 35% of wheat samples were contaminated with ZEA in the range of 51.65 μg kg-1–126.54 μg kg-1 and in 29% barley samples the contamination was between 48.67–79.64 µg kg-1. OTA pollution was registered in 19% of wheat samples in the range 4.86–7.32 µg kg-1 and in 29% barley samples it was between 4.46–11.70 µg kg-1 respectively. In all of the investigated samples the contamination with OTA and ZEA is bellow the limit set in the valid EC Recommendation 576/2006/EC. [ABSTRACT FROM AUTHOR]

Recognized as the causal agent of net blotch, Drechslera teres is responsible for major losses of barley crop yield. The consequences of this leaf disease are due to the impact of the infection on the photosynthetic performance of barley leaves. To limit the symptoms of this ascomycete, the use of beneficial bacteria known as "Plant Growth Promoting Rhizobacteria" constitutes an innovative and environmentally friendly strategy. A bacterium named as strain B25 belonging to the genus Burkholderia showed a strong antifungal activity against D. teres. The bacterium was able to limit the development of the fungus by 95% in detached leaves of bacterized plants compared to the non-bacterized control. In this study, in-depth analyses of the photosynthetic performance of young barley leaves infected with D. teres and/or in the presence of the strain B25 were carried out both in and close to the necrotic area. In addition, gas exchange measurements were performed only near the necrotic area. Our results showed that the presence of the beneficial bacterium reduced the negative impact of the fungus on the photosynthetic performance and modified only the net carbon assimilation rate close to the necrotic area. Indeed, the presence of the strain B25 decreased the quantum yield of regulated non-photochemical energy loss in PSII noted as Y(NPQ) and allowed to maintain the values stable of maximum quantum yield of PSII photochemistry known as Fv/Fm and close to those of the control in the presence of D. teres. To the best of our knowledge, these data constitute the first study focusing on the impact of net blotch fungus and a beneficial bacterium on photosynthesis and respiratory parameters in barley leaves. [ABSTRACT FROM AUTHOR]

Spot blotch (SB) caused by Cochliobolus sativus presents a serious problem for barley production worldwide, and identification new sources of resistance is a key objective for many breeders. Breeding for resistance is an economically and environmentally friendly approach to reduce negative effects of the disease, and understanding the genetic basis of this resistance can enhance the development of resistant varieties. With that goal, F2 barley recombinant lines obtained from a cross of highly barley resistant cv. Banteng and the susceptible cv. WI2291 were tested for SB resistance which supported by AFLP markers. Following greenhouse evaluations under SB artificial infection conditions, results demonstrated different significant levels among barley recombinant lines ranged from highly susceptible to resistant. However, out of the 54 recombinant lines, 25 were resistant than the others which had 7 AFLP unique bands at different regions in the genome, this distribution and resistance or susceptibility can indicate that some positive or negative markers are common either to resistant or susceptible lines. The unique and common AFLP bands might be of considerable interest for enhancing effective resistance to SB. [ABSTRACT FROM AUTHOR]

Powdery mildew, caused by the fungal pathogen Blumeria graminis (Bg) is one of the most important foliar diseases of barley globally. Barley plants have evolved complex signaling pathways during defense response against Bg, including plant hormones such as salicylic acid (SA) and pathogenesisrelated proteins. Therefore, to better understand the defense mechanisms of resistant barley plants attacked by Bg, cooperative functioning between mla1, mla6, mla12, Rac1 genes and SA was evaluated at early time points of infection. mRNA was isolated 1, 2, 3, 4 and 6 days post inoculation and used for cDNA synthesis. The expression of mla and Rac1 genes was quantified using Quantitative reverse transcriptase PCR (qRT-PCR). SA measurement was performed by a high-performance liquid chromatography (HPLC) system. Data showed a remarkable increase in the expression patterns of mla and Rac1genes accompanied with an increase in SA level in infected plants 1 day post inoculation (dpi) when compared with non-infected plants. The most outstanding differences were observed in mla1 and Rac1 expressions which were 6.27 and 3.55 folds respectively higher, 4 dpi of barley Bg interaction, and were accompanied with an elevated SA level (610 ng/g). According to findings, this study might increase our understanding for a deeper molecular research on the cooperative functioning of mla & Rac1 genes and SA in resistant barley responses against Bg. [ABSTRACT FROM AUTHOR]

Chinese pearl barley (Coix chinensis Tod.) is grown worldwide as a cereal food and medicinal plant. During 2016 and 2017, a severe leaf blight outbreak was observed in Nanjing prefecture, Fujian Province, China. The disease outbreak affected almost 100% of the Chinese pearl barley plants under field conditions. The pathogen was isolated from infected leaves showing typical symptoms of dark brown spots surrounded by yellow halos, and was identified as Curvularia coicis Castellani based on morphological characteristics and sequencing of the ribosomal DNA internal transcribed spacer (rDNA-ITS). The optimal temperature for mycelial growth of C. coicis on potato dextrose agar (PDA) ranged from 25°C to 28°C. Pathogenicity assays were performed using Chinese pearl barley 'Longyi 1' at the seven- to eight-leaf stage. Overall, C. coicis had a high virulence on these inoculated plants, even in the absence of wounds, and the pathogen was successfully reisolated. The results from this study identified the causal organism of leaf blight on Chinese pearl barley. [ABSTRACT FROM AUTHOR]

The effect of the colonization of barley plants (Hordeum vulgare L.) by the associative microorganisms Pseudomonas putida BS3701 on the adaptation of the photosynthetic apparatus to high light intensity was studied. A number of differences were found in the functioning and structure of the photosynthetic apparatus of the control plants and plants colonized by P. putida BS3701 grown at 100 µmol quanta/m2 s. The barley plants colonized by P. putida BS3701 were shown to have an increased resistance to high light intensity (1000 µmol quanta/m2 s) when compared to the control plants. It was established that the adaptive decrease in the PSII antenna size was characterized by the same molecular mechanism in both the control plants and plants colonized by P. putida ВS3701. However, the decrease in PSII antenna size was more pronounced in plants colonized by P. putida ВS3701. It can be assumed that this might be the cause of more efficient protection of the photosynthetic apparatus of plants colonized by P. putida BS3701 against photoinhibition under high illumination. [ABSTRACT FROM AUTHOR]

Powdery mildew disease, caused by Blumeria graminis f. sp. hordei (Bgh), is one of the important diseases of barley. Hordeum vulgare Signal Recognition Particle 72 (HvSRP72) was previously identified as differentially induced at 6 h and/or 12 h after infection in powdery mildew disease resistance, suggesting its involvement in pathogen response. Since there is limited information on R gene-mediated signaling cascade, we sought to understand the way which HvSRP72 protein functions in powdery mildew resistance or susceptibility response. HvSRP72 was silenced by barley stripe mosaic virus (BSMV)-induced gene silencing, in order to understand its role in the plant response to pathogen infection. The level of HvSRP72 mRNA in silenced plant samples showed an average 57% reduction with respect to control plants (BSMV:00). The change in resistance or susceptibility to powdery mildew in HvSRP72-silenced plant leaves was determined by measuring the length of hyphal extensions and the germination efficiency upon inoculation. Under susceptible conditions, in HvSRP72-silenced samples spores germinated approximately four times more efficiently and Bgh development was also increased twice with respect to control plants. On the other hand, under the resistant condition, no difference was observed in HvSRP72-silenced samples when compared to the non-silenced ones. Thus, it can be concluded that silencing of HvSRP72 enhances Blumeria graminis f. sp. hordei susceptibility but no change of hyphal growth was observed during resistance response. [ABSTRACT FROM AUTHOR]

Early detection of foliar diseases is vital to the management of plant disease, since these pathogens hinder crop productivity worldwide. This research applied hyperspectral imaging (HSI) technology to early detection of Magnaporthe oryzae -infected barley leaves at four consecutive infection periods. The averaged spectra were used to identify the infection periods of the samples. Additionally, principal component analysis (PCA), spectral unmixing analysis and spectral angle mapping (SAM) were adopted to locate the lesion sites. The results indicated that linear discriminant analysis (LDA) coupled with competitive adaptive reweighted sampling (CARS) achieved over 98% classification accuracy and successfully identified the infected samples 24 h after inoculation. Importantly, spectral unmixing analysis was able to reveal the lesion regions within 24 h after inoculation, and the resulting visualization of host–pathogen interactions was interpretable. Therefore, HSI combined with analysis by those methods would be a promising tool for both early infection period identification and lesion visualization, which would greatly improve plant disease management. [ABSTRACT FROM AUTHOR]

Ramularia leaf spot has recently emerged as a major threat to barley production world-wide, causing 25% yield loss in many barley growing regions. Here, we provide a new reference genome of the causal agent, the Dothideomycete Ramularia collo-cygni. The assembly of 32 Mb consists of 78 scaffolds. We used RNA-seq to identify 11,622 genes of which 1,303 and 282 are coding for predicted secreted proteins and putative effectors respectively. The pathogen separated from its nearest sequenced relative, Zymoseptoria tritici ∼27 Ma. We calculated the divergence of the two species on protein level and see remarkably high synonymous and nonsynonymous divergence. Unlike in many other plant pathogens, the comparisons of transposable elements and gene distributions, show a very homogeneous genome for R. collo-cygni. We see no evidence for higher selective pressure on putative effectors or other secreted proteins and repetitive sequences are spread evenly across the scaffolds. These findings could be associated to the predominantly endophytic life-style of the pathogen. We hypothesize that R. collo-cygni only recently became pathogenic and that therefore its genome does not yet show the typical pathogen characteristics. Because of its high scaffold length and improved CDS annotations, our new reference sequence provides a valuable resource for the community for future comparative genomics and population genetics studies. [ABSTRACT FROM AUTHOR]

Fusarium Head Blight (FHB) is a major constraint to barley production that substantially reduces yield and grain quality. FHB is also a major food safety concern because FHB pathogens contaminate grain with trichothecenes and other mycotoxins. DNA sequence-based analyses and in-vitro toxin assessments were used to characterize the species and trichothecene chemotype composition of FHB pathogens on barley in Uruguay. F . graminearum was the dominant species (89.7%), and three other members of the F. graminearum species complex (FGSC) were identified as FHB pathogens of barley in Uruguay for the first time. Other minor contributors to FHB species diversity included F . poae, F . avenaceum , F. pseudograminearum and an unnamed species from the F . incarnatum - equiseti species complex (FIESC). Most isolates (89.7%) had the 15-acetyldeoxynivalenol (15-ADON) trichothecene type. However, the results expanded the known area of occurrence within Uruguay for the nivalenol (NIV) toxin type, which was observed among isolates from three species of the FGSC, F . pseudograminearum , and F . poae . Isolates with the 3-acetyldeoxynivalenol (3-ADON) or NX-2 toxin types were not observed, although a previously published multilocus genotyping assay was updated to identify NX-2 strains. Analyses of population structure and comparisons with FHB isolates from wheat in Uruguay indicated that F . graminearum constitutes a single genetic population with no evidence of population differentiation related to the sampled hosts. Inter and intraspecific differences were observed in aggressiveness toward four barley genotypes with different levels of resistance to FHB, and in general nivalenol producers were the least aggressive isolates. Sensitivity to metconazole was approximately 10 times higher than was detected for tebuconazole. This is the first report regarding tebuconazole and metconazole sensitivity for Fusarium species causing FHB in barley in Uruguay, and constitutes an important starting point for monitoring temporal or spatial changes in FGSC sensitivity, which is critical to define FHB management practices. [ABSTRACT FROM AUTHOR]

Key message: The quantitative barley leaf rust resistance gene, Rph26, was fine mapped within a H. bulbosum introgression on barley chromosome 1HL. This provides the tools for pyramiding with other resistance genes.Abstract: A novel quantitative resistance gene, Rph26, effective against barley leaf rust (Puccinia hordei) was introgressed from Hordeum bulbosum into the barley (Hordeum vulgare) cultivar ‘Emir’. The effect of Rph26 was to reduce the observed symptoms of leaf rust infection (uredinium number and infection type). In addition, this resistance also increased the fungal latency period and reduced the fungal biomass within infected leaves. The resulting introgression line 200A12, containing Rph26, was backcrossed to its barley parental cultivar ‘Emir’ to create an F2 population focused on detecting interspecific recombination within the introgressed segment. A total of 1368 individuals from this F2 population were genotyped with flanking markers at either end of the 1HL introgression, resulting in the identification of 19 genotypes, which had undergone interspecific recombination within the original introgression. F3 seeds that were homozygous for the introgressions of reduced size were selected from each F2 recombinant and were used for subsequent genotyping and phenotyping. Rph26 was genetically mapped to the proximal end of the introgressed segment located at the distal end of chromosome 1HL. Molecular markers closely linked to Rph26 were identified and will enable this disease resistance gene to be combined with other sources of quantitative resistance to maximize the effectiveness and durability of leaf rust resistance in barley breeding. Heterozygous genotypes containing a single copy of Rph26 had an intermediate phenotype when compared with the homozygous resistant and susceptible genotypes, indicating an incompletely dominant inheritance. [ABSTRACT FROM AUTHOR]

Abstract: Key messageMajor stem rust resistance QTLs proposed to beRpg2from Hietpas-5 andRpg3from GAW-79 were identified in chromosomes 2H and 5H, respectively, and will enhance the diversity of stem rust resistance in barley improvement programs.Abstract: Stem rust is a devastating disease of cereal crops worldwide. In barley (Hordeum vulgare ssp. vulgare), the disease is caused by two pathogens: Puccinia graminis f. sp. secalis (Pgs) and Puccinia graminis f. sp. tritici (Pgt). In North America, the stem rust resistance gene Rpg1 has protected barley from serious losses for more than 60 years; however, widely virulent Pgt races from Africa in the Ug99 group threaten the crop. The accessions Hietpas-5 (CIho 7124) and GAW-79 (PI 382313) both possess moderate-to-high levels of adult plant resistance to stem rust and are the sources of the resistance genes Rpg2 and Rpg3, respectively. To identify quantitative trait loci (QTL) for stem rust resistance in Hietpas-5 and GAW-79, two biparental populations were developed with Hiproly (PI 60693), a stem rust-susceptible accession. Both populations were phenotyped to the North American Pgt races of MCCFC, QCCJB, and HKHJC in St. Paul, Minnesota, and to African Pgt races (predominately TTKSK in the Ug99 group) in Njoro, Kenya. In the Hietpas-5/Hiproly population, a major effect QTL was identified in chromosome 2H, which is proposed as the location for Rpg2. In the GAW-79/Hiproly population, a major effect QTL was identified in chromosome 5H and is the proposed location for Rpg3. These QTLs will enhance the diversity of stem rust resistance in barley improvement programs. [ABSTRACT FROM AUTHOR]

Rhynchosporium commune is a destructive pathogen of barley, causing leaf scald. Previous microsatellite studies used Syria as a representative of cultivated barley's centre of origin, the Fertile Crescent. These suggested that R. commune and Hordeum vulgare (cultivated barley) did not co‐evolve in the host's centre of origin. The present study compares R. commune populations from Syria with those from Iran, which represents a secondary centre of origin for barley at the eastern edge of the Iranian Plateau. Results from this study also suggest that R. commune and barley did not co‐evolve in the centre of origin of cultivated barley. This was evidenced by the low pathogen genetic diversity in Iran, which was even lower than in Syria, indicating that the pathogen may have been introduced recently into Iran, perhaps through infected barley seed. Hierarchical analyses of molecular variance revealed that most genetic diversity in Iran and Syria is distributed within populations, with only 14% among populations. Analyses of multilocus association, genotype diversity and mating type frequency suggest that Iranian populations reproduce predominantly asexually. The presence of both mating types on barley and uncultivated grasses suggest a potential for sexual reproduction. Rhynchosporium commune was also found on Hordeum murinum subsp. glaucum, H. vulgare subsp. spontaneum, Lolium multiflorum and, for the first time, on Avena sativa. The variety of wild grasses that can be infected with R. commune in Iran raises concerns of these grasses acting as evolutionary breeding grounds and sources of inoculum. [ABSTRACT FROM AUTHOR]

Integrated Pest Management (IPM) offers a suite of ways by which to reduce the need for pesticide use, thus minimising environmental damage and pathogen resistance build-up in crop production. Farmers and agronomists active in the Scottish spring barley sector were surveyed to determine the extent to which they currently use or are open to implementing three IPM measures – varietal disease resistance, crop rotation, and forecasting disease pressure – in order to control three important fungal diseases. Overall, the survey results demonstrate that farmers and agronomists are open to using the three IPM techniques. However, gaps between actual and perceived recent practice were large: despite over 60% of farmers stating that they sowed varieties highly resistant to Rhynchosporium or Ramularia, less than one third of reportedly sown varieties were highly resistant to these diseases. Similarly, over 80% of farmers indicated that they used crop rotations, yet 66% of farmers also reported sowing consecutive barley often/always. Further research is needed in order to understand why these gaps exist, and how they can be reduced in future in order to increase IPM uptake and optimise pesticide use. [ABSTRACT FROM AUTHOR]

Barley stem gall midge, Mayetiola hordei (Kieffer) (Diptera: Cecidomyiidae) is among the most destructive pests of barley ( Hordeum vulgare L.) in the Mediterranean region of southern Europe and northern Africa. In Tunisia, the biology and ecology of this pest are not well documented. In addition to a management study, a study of M. hordei distribution, frequency of occurrence and population dynamics in barley crops was conducted in two semi-arid regions of North Tunisia. The pest was detected in 84% of all sampled fields across two years. Zaghouan region was identified as a high spot region with economic infestations registered in 67 and 56% of surveyed fields in 2013 and 2014, respectively. Three annual generations occurred at both sites, with two complete and one incomplete generation. The second generation (winter generation) is the most important one in terms of crop damage. The study showed that damage from this pest affects host plant growth at different developmental stages. The highest infestation was observed during tillering and elongation. The impact of different sowing date of barley on M. hordei infestation was also conducted. The infestation rate of barley by M. hordei increased by delaying sowing date. We demonstrate that M. hordei is a serious biosecurity threat to Tunisian barley's production and industry. [ABSTRACT FROM AUTHOR]

Occurrence of genus Fusarium as endophytes in roots of healthy barley plants cultivated in fields under two levels of phosphorous (P) was examined. F. avenaceum, F. graminearum, F. konzum, F. oxysporum, F. sacchari, F. scirpi, F. solani were isolated from asymptomatic surface sterilized root tissues. F. konzum and F. solani were only present in the roots of fertilized plants, whereas F. sacchari was present in unfertilized plants. F. scirpi was isolated in highest frequency and relative density, and was higher under P deficiency suggesting that P availability would determinate the occurrence of this species, suggesting the possibility of their association with stressed plants. This is the first report on the occurrence of Fusarium spp. as endophytes in healthy barley plants. However, it remains to be determined whether Fusarium spp. isolated are nonpathogenic forms and beneficial to barley plants or latent pathogens that could produce disease symptoms in other conditions. [ABSTRACT FROM AUTHOR]

To ascertain the presence of Barley/Cereal yellow dwarf viruses (BYDV-PAV, MAV, SGV, RMV, and CYDV-RPV), a total of 365 wheat leaf samples were randomly collected from wheat cultivation fields of Diyarbakir province in 2016 and were screened by using multiplex RT-PCR and RT-PCR methods. As a result of PCR tests the wheat samples were found to be infected by BYDV-PAV, BYDV-SGV and CYDV-RPV with the percentage of 3.5%, 2.4% and 1.3%, respectively. Detected mix infections of BYDV-PAV+BYDV-SGV, BYDV-PAV+CYDV-RPV, BYDV-SGV+CYDV-RPV, and BYDV-PAV+BYDV-SGV+CYDV-RPV were 2.2%, 0.8%, 0.8%, and 0.8%, respectively. A BYDV-PAV Diyarbakir isolate was chosen randomly, and its complete coat protein gene was characterized. The coat protein gene of BYDV-PAV virus (Genbank accession no. KX774424) was molecularly cloned and sequenced with the universal primers. The CP nucleotide sequence of BYDV-PAV Diyarbakir isolate was showed 81.4 - 98.3% identities with the other 21 world isolates. The present study is the first report for documentation of BYDV-PAV, BYDV-SGV and CYDV-RPV viruses in wheat fields of Diyarbakir province (Turkey). [ABSTRACT FROM AUTHOR]

Surveys were conducted in commercial wheat and barley fields in the south central production regions of state of Paraná, Brazil, from 2011 to 2015. Spikes displaying visible Fusarium head blight symptoms were collected and the pathogen isolated from the tissues. The 754 Fusarium isolates recovered were identified by a high-throughput multilocus genotyping assay (MLGT) designed to identify trichothecene toxin-producing fusaria (i.e., formerly B-clade, but referred to here as F. sambucinum species complex lineage 1 [FSAMSC-1]) together with sequencing a portion of the translation elongation factor 1-α (TEF1) gene. One strain was discovered that appeared to be closely related to but phylogenetically distinct from F. praegraminearum based on the relatively low 97.7% TEF1 identity and positive genotype obtained with one of the two F. praegraminearum species-specific MLGT probes. Molecular phylogenetic analyses of a 10-gene data set resolved this novel FSAMSC-1 species and F. praegraminearum as sisters. Formally described herein as F. subtropicale, it is phenotypically distinct from the 22 other FSAMSC-1 species in that it produces mostly 1-3-septate macroconidia. Whole-genome sequence data were used to predict its potential to produce mycotoxins. Chemical analyses confirmed that F. subtropicale could produce the mycotoxins 4,15-diacetylnivalenol, butenolide, culmorin, and fusarin C in vitro, and the pathogenicity experiment revealed that F. subtropicale could infect but not spread in susceptible hard red spring wheat cultivar "Norm." [ABSTRACT FROM AUTHOR]

Scald (Rhynchosporium secalis; Rs) and spot blotch (Cochliobolus sativus; Cs) are important diseases of barley (Hordeum vulgare L.) worldwide. Similar mechanisms and gene transcripts are assumed to be involved in the barley defense response since both these pathogens are necrotrophic fungi. In the current study, the transcriptome in leaves of the same barley genotype WI2291 inoculated with Rs and Cs was compared at different times postinoculation. Comparison of data for barley Rs- and Cs- inoculated plants with mockinoculated plants revealed gene expression changes that included basal defense transcripts and transcripts specific to the establishment of a necrotrophic interaction with associated fungi. During barley-pathogen interaction pathway, WI2291 activated a higher number of genes and pathways in response to Rs infection than in response to Cs invasion. However, families of genes encoding pectin-degrading enzymes, secondary metabolism enzymes, transporters and peptidases are expanded to cover Rs and Cs at an early stage following inoculation. Our results demonstrate differences in the pathways and activated genes of barely cv. WI291challenged by Rs and Cs, and that expression patterns of the same defenseassociated genes were altered in adaptation to different pathogens. Our work provides new insights into the underlying mechanisms related to regulation of different pathways in response to fungal infection. [ABSTRACT FROM AUTHOR]

One of the biotic agents of yellowing and stunting in wheat and barley cultivations is Wheat dwarf virus (WDV) which is naturally transmitted by the leafhopper Psammotettix alienus (Dahlbom). WDV-Wheat and WDV-Barley isolates of WDV were transmitted to wheat and barley, respectively, using the leafhoppers under four temperature regimes of constant 20, 25, 30, and 35°C. Infection rate, symptom development and virus content of the virus-inoculated plants were determined and the data was statistically analysed. The results showed that the temperature of 25°C was associated with the highest infection rate caused by the viruses. Moreover, P. alienus nymphs were found to be more efficient vectors of WDV than adults, highlighting the importance of nymphs in the epidemiology of wheat dwarf disease. WDV-infected plants incubated at 35°C showed less symptoms than those kept at 20, 25, and 30°C. ELISA results showed that these plants had comparatively low virus content. However, there was no significant difference between the infection rate, symptom development and virus content in plants infected by WDV-Wheat or WDV-Barley. [ABSTRACT FROM AUTHOR]

Fusarium graminearum is a fungal pathogen that causes Fusarium head blight (FHB) in wheat and barley. Autophagy is a highly conserved vacuolar degradation pathway essential for cellular homeostasis in which Atg9 serves as a multispanning membrane protein important for generating membranes for the formation of phagophore assembly site. However, the mechanism of autophagy or autophagosome formation in phytopathogens awaits further clarifications. In this study, we identified and characterized the Atg9 homolog (FgAtg9) in F. graminearum by live cell imaging, biochemical and genetic analyses. We find that GFP-FgAtg9 localizes to late endosomes and trans-Golgi network under both nutrient-rich and nitrogen starvation conditions and also show its dynamic actin-dependent trafficking in the cell. Further targeted gene deletion of FgATG9 demonstrates that it is important for growth, aerial hyphae development, and pathogenicity in F. graminearum. Furthermore, the deletion mutant (ΔFgatg9) shows severe defects in autophagy and lipid metabolism in response to carbon starvation. Interestingly, small GTPase FgRab7 is found to be required for the dynamic trafficking of FgAtg9, and co-immunoprecipitation (Co-IP) assays show that FgAtg9 associates with FgRab7 in vivo. Finally, heterologous complementation assay shows that Atg9 is functionally conserved in F. graminearum and Magnaporthe oryzae. Taken together, we conclude that FgAtg9 is essential for autophagy-dependent development and pathogenicity of F. graminearum, which may be regulated by the small GTPase FgRab7. [ABSTRACT FROM AUTHOR]

Phytopathogens deploy secreted effector proteins that interfere with different host cellular pathways to suppress plant immunity and redirect nutrient flow. Conventional effectors are small polypeptides with an N-terminal secretion signal, no transmembrane domain and often lacking any protein domain annotation. In their current work, Nottensteiner et al. (2018) provide experimental evidence for the existence of an unconventional, seemingly retrotransposon-derived effector of the barley powdery mildew fungus. This protein (ROPIP1) interacts with the barley susceptibility factor RACB, possibly leading to local destabilization of cortical microtubular network architecture, thereby supporting fungal host cell entry. [ABSTRACT FROM AUTHOR]

Summary: The filamentous fungus Fusarium graminearum, a devastating pathogen of barley (Hordeum vulgare L.), produces mycotoxins that pose a health hazard. To investigate the surface interactions of F. graminearum on barley, we focused on barley florets, as the most important infection site leading to grain contamination. The fungus interacted with silica‐accumulating cells (trichomes and silica/cork cell pairs) on the host surface. We identified variation in trichome‐type cells between two‐row and six‐row barley, and in the role of specific epidermal cells in the ingress of F. graminearum into barley florets. Prickle‐type trichomes functioned to trap conidia and were sites of fungal penetration. Infections of more mature florets supported the spread of hyphae into the vascular bundles, whereas younger florets did not show this spread. These differences related directly to the timing and location of increases in silica content during maturation. Focal accumulation of cellulose in infected paleae of two‐row and six‐row barley indicated that the response is in part linked to trichome type. Overall, silica‐accumulating epidermal cells had an expanded role in barley, serving to trap conidia, provide sites for fungal ingress and initiate resistance responses, suggesting a role for silica in pathogen establishment. [ABSTRACT FROM AUTHOR]

Aggressiveness variation among 16 isolates of four Fusarium species (F. culmorum, F. solani, F. verticillioides and F. equiseti) causing Fusarium head blight (FHB) was studied in vitro. Evaluation of three aggressiveness criteria involved in a Petri-dish test: germination rate reduction, standardized area under disease progress curve (AUDPCstandard), and coleoptile length reduction was carried out on the barley cultivar Arabi Aswad. Results showed differences between barley plants inoculated with FHB isolates and control for the three tested aggressiveness criteria. Regarding AUDPCstandard and Petri-dish aggressiveness index which is calculated from the mean value of three aggressiveness criteria, within and among variation was detected. Intra- and inter-species variability was not distinguished for the other two aggressiveness criteria. However, pathogenic level observed among 16 isolates can not be differentiated within the four FHB species. Significant correlation was detected only between AUDPCstandard and Petri-dish aggressiveness index. The results were comparable with those previously obtained using the same fungal isolates on wheat cultivar in vitro. It seems that FHB isolates recovered from wheat spikes and tested on wheat plants showed a similar range of aggressiveness on a barley cultivar, Arabi Aswad. [ABSTRACT FROM AUTHOR]

In recent years, due to the negative impact of toxigenic mycobiota and of the accumulation of their secondary metabolites in malting barley grains, monitoring the evolution of fungal communities in a certain cultivation area as well as detecting the different mycotoxins present in the raw material prior to malting and brewing processes have become increasingly important. In this study, a survey was carried out on malting barley samples collected after their harvest in the Umbria region (central Italy). Samples were analyzed to determine the composition of the fungal community, to identify the isolated Fusarium species, to quantify fungal secondary metabolites in the grains and to characterize the in vitro mycotoxigenic profile of a subset of the isolated Fusarium strains. The fungal community of barley grains was mainly composed of microorganisms belonging to the genus Alternaria (77%), followed by those belonging to the genus Fusarium (27%). The Fusarium head blight (FHB) complex was represented by nine species with the predominance of Fusarium poae (37%), followed by Fusarium avenaceum (23%), Fusarium graminearum (22%) and Fusarium tricinctum (7%). Secondary metabolites biosynthesized by Alternaria and Fusarium species were present in the analyzed grains. Among those biosynthesized by Fusarium species, nivalenol and enniatins were the most prevalent ones. Type A trichothecenes (T-2 and HT-2 toxins) as well as beauvericin were also present with a high incidence. Conversely, the number of samples contaminated with deoxynivalenol was low. Conjugated forms, such as deoxynivalenol-3-glucoside and HT-2-glucoside, were detected for the first time in malting barley grains cultivated in the surveyed area. In addition, strains of F. avenaceum and F. tricinctum showed the ability to biosynthesize in vitro high concentrations of enniatins. The analysis of fungal secondary metabolites, both in the grains and in vitro , revealed also the presence of other compounds, for which further investigations will be required. The combination of microbiological analyses, of molecular biology assays and of multi-mycotoxin screening shed light on the complexity of the fungal community and its secondary metabolites released in malting barley. [ABSTRACT FROM AUTHOR]

Barley is a host to Puccinia striiformis f. sp. hordei, and is an intermediate or near nonhost to the formae speciales adapted to wheat (P. striiformis f. sp. tritici) and to barley grass (P. striiformis f. sp. pseudohordei). The genetic basis of resistance to these forms of P. striiformis is not well understood. Accordingly, a recombinant inbred line (R1L) population was developed using a P. stra/omu-susceptible accession (Biosaline-19) and the immune cultivar Pompadour. We investigated the genetic basis of resistance to four diverse P. striiformis isolates (P. striiformis f. sp. pseudohordei, and P. striiformis f. sp. tritici pathotypes 104 E137 A-, 134 EI6 A+, and 64 EO A-). and determined that the immunity in Pompadour at the seedling stage to the different P. striiformis isolates was due to quantitative trait loci (QTL) on chromosomes 1H, 3H, 5H, and 7H with both overlapping and distinct specificities. Further histological analysis confirmed the presence of isolate specificity. The RILs were also assessed in the field for resistance to P. striiformis f. sp. pseudo-hordei, P. striiformis f. sp. hordei, and the leaf rust pathogen (P. hordei) to identify pleiotropic QTL loci effective at the adult plant stage and determine whether the leaf rust resistance in Pompadour (Rph20) was also effective to P. striiformis. RILs that were seedling susceptible to P. striiformis f. sp. pseudo-hordei were resistant in the field, implicating the involvement of adult plant resistance (APR). Additional QTLs were identified on chromosome 7H at the same genetic position as Rpli23 (APR to leaf rust), suggesting either pleiotropic resistance or the presence of a stripe rust resistance gene closely linked to or allelic with Rph23. Unlike many pleiotropic APR genes identified and isolated in wheat, our data suggest that the Rph20 locus does not confer resistance to the P. striiformis isolates used in this study (P. striiformis f. sp. hordei [X2 (independence) = 2.47 P > 0.12] and P. striiformis f. sp. pseudo-hordei [X2 (independence) = 0.42 P > 0.60]). [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]

Fusarium culmorum (W.G. Smith) leads to economic losses in wheat and barley fields in Turkey as well as in many countries worldwide as a result of head blight and crown rot diseases. In this study, in vitro growth capacity of 33 F. culmorum isolates originating from Turkey and the relationship between phenotypic and genetic characteristics obtained based on similarities of FcMgv1, FcStuA and FcVeA genes were investigated. Linear growth rate values were recorded at 4th and 7th days of incubation. The mean linear growth rate values ranged from 7.58±1.06 to 14.7±1.26mm/day. The isolates F2 and 18F with relatively high linear growth values and the isolates 12F and F19 with relatively low linear growth values, were selected to be used in multiloci based genotyping analysis. FcMgv1, FcStuA and FcVeA genes were amplified in lengths of 1733, 2001 and 1898bp, respectively. The genes were sequenced, aligned and then subjected to BLASTn and to maximum likelihood topology analysis. Nucleotide sequence of each gene showed maximum hit with associated genes deposited in NCBI with 0.0-0.0 Evalues and 1188 to 3256 bit scores. Alignment analysis resulted in at least 89% bootstrap support. Moreover, isolates with similar linear growth rates were co-clustered in phylogenetic analysis. The findings obtained in this study showed that the three genes which are essential for fungal survival could be used in genetic characterization analysis and in revealing the associations between their genetic and phenotypic characteristics. [ABSTRACT FROM AUTHOR]

Twenty-four Alternaria strains were isolated from barley grain samples. These strains were screened for the production of mycotoxins on rice medium using thin layer chromatography. All 24 strains produced at least one of the five mycotoxins (ALT, AOH, ATX-I, AME, and TeA). Three representative strains, namely EML-BLDF1-4, EML-BLDF1-14, and EML-BLDF1-18, were further analyzed using a new LC–MS/MS-based mycotoxin quantification method. This method was used to detect and quantify Alternaria mycotoxins. We used positive ion electrospray mass spectrometry with multiple reaction mode (MRM) for the simultaneous quantification of various Alternaria mycotoxins produced by these strains. Five Alternaria toxins (ALT, ATX-I, AOH, AME, and TeA) were detected and quantified. Sample preparation included methanol extraction, concentration, and injection into LC–MS/MS. Limit of detection ranged from 0.13 to 4 μg/mL and limit of quantification ranged from 0.25 to 8 μg/mL. [ABSTRACT FROM AUTHOR]

Infections of one host by multiple parasites are common, and several studies have found that the order of parasite invasion can affect both within-host competition and disease severity. However, it is unclear to what extent coinfection timing might be important to consider when modeling parasite impacts on host populations. Using a model system of two viruses infecting barley, we found that simultaneous infections of the two viruses were significantly more damaging to hosts than sequential coinfections. While priority effects were evident in within-host concentrations of sequential coinfections, priority did not influence any parameters (such as virulence or transmission rate) that affect host population dynamics. We built a susceptible-infected model to examine whether the observed difference in coinfection virulence could impact host population dynamics under a range of scenarios. We found that coinfection timing can have an important but context-dependent effect on projected host population dynamics. Studies that examine only simultaneous coinfections could inflate disease impact predictions. [ABSTRACT FROM AUTHOR]

Summary: Bipolaris sorokiniana is the causal agent of multiple diseases on wheat and barley and is the primary constraint to cereal production throughout South Asia. Despite its significance, the molecular basis of disease is poorly understood. To address this, the genomes of three Australian isolates of B. sorokiniana were sequenced and screened for known pathogenicity genes. Sequence analysis revealed that the isolate BRIP10943 harboured the ToxA gene, which has been associated previously with disease in the wheat pathogens Parastagonospora nodorum and Pyrenophora tritici‐repentis. Analysis of the regions flanking ToxA within B. sorokiniana revealed that it was embedded within a 12‐kb genomic element nearly identical to the corresponding regions in P. nodorum and P. tritici‐repentis. A screen of 35 Australian B. sorokiniana isolates confirmed that ToxA was present in 12 isolates. Sequencing of the ToxA genes within these isolates revealed two haplotypes, which differed by a single non‐synonymous nucleotide substitution. Pathogenicity assays showed that a B. sorokiniana isolate harbouring ToxA was more virulent on wheat lines that contained the sensitivity gene when compared with a non‐ToxA isolate. This work demonstrates that proteins that confer host‐specific virulence can be horizontally acquired across multiple species. This acquisition can dramatically increase the virulence of pathogenic strains on susceptible cultivars, which, in an agricultural setting, can have devastating economic and social impacts. [ABSTRACT FROM AUTHOR]

Fusarium head blight of malting barley is difficult to diagnose and difficult to prevent by crop protection measures. However, Fusarium species cause severe problems in processing barley grain and cause contaminations of malt and malt products with fungal toxins and possibly with toxin derivates. Therefore, we briefly summarize at which stage of malt production Fusarium infections cause which kind of problems and how such problems can be possibly managed in future malt production practice. We argue for a stronger focus on innovative diagnostics and development of appropriate crop protection measures to prevent problems Fusarium species cause once infected barley grain has entered the value chain. [ABSTRACT FROM AUTHOR]

Bacterial black node caused by Pseudomonas syringae pv. syringae is the most serious bacterial disease of barley and wheat in Japan. The spatiotemporal distribution of barley and wheat plants infected with bacterial black node in fields in 2016-2017 was analyzed using Taylor's model and Iwao's model. In Taylor's model, the sample variance ( s ) of the total and the newly diseased plants at each observation increased with mean plant density ( m). In Iwao's model, although the mean crowding ( m*) of total and newly recognized diseased plants increased with m, Taylor's model fit the data better than did Iwao's model. Thus, bacterial black node could be explained as a colony expansion model. [ABSTRACT FROM AUTHOR]

The presence of mycotoxins in animal feed cause health disorders and can also contribute to other factors such as stress, lack of nutrition, infectious agents etc. The aim of this article was to study effect of feed ration contaminated with mycotoxins on liver histology and live weight of laboratory rats. 15 pieces of laboratory rats were divided into 3 groups (A, B, C). The rats in first group (A) fed with part of 30 % mycotoxin-contaminated barley, in second group (B were fed with 60 % and in control group (C) were fed without mycotoxin-contaminated barley. Content of deoxynivalenol (DON) was 9634 µg / kg and content of zearalenone (ZEN) was 2192 µg / kg. Barley monodietus were given rats in all groups to induce a nutritional imbalance. The aim of this study was to monitor the effect of mycotoxins and nutritional imbalances on weight gains and liver histology. The question is, "will the presence of mycotoxins in feed dose increase negative effect of a monodiets on health status?" No significant differences were found between the observed parameters. The presence of mycotoxins did not aggravate the negative effect of the monodiets on liver histology of the experimental rats. [ABSTRACT FROM AUTHOR]

Background: Spot blotch, caused by Cochliobolus sativus, is one of the most widespread and harmful diseases in barley. Identification of genetic loci associated with resistance to C. sativus is of importance for future marker-assisted selection. The goal of the current study was to identify loci conferring seedling resistance to two different pathotypes of C. sativus in the Siberian spring barley core collection. Results: A total of 96 spring barley cultivars and lines were phenotyped at the seedling stage with two C. sativus isolates (Kr2 and Ch3). According to the Fetch-Steffenson rating scale 16%/17% of genotypes were resistant and 26%/30% were moderate-resistant to the Kr2/Ch3 isolates respectively. A total of 94 genotypes were analyzed with the barley 50 K Illumina Infinium iSELECT assay. From 44,040 SNPs, 40,703 were scorable, from which 39,140 were polymorphic. 27,319 SNPs passed filtering threshold and were used for association mapping. Data analysis by GLM revealed 48 and 41 SNPs for Kr2 and Ch3 isolates, respectively. After application of 5% Bonferroni multiple test correction, only 3 and 27 SNPs were identified, respectively. A total of three genomic regions were associated with the resistance. The region on chromosome 3H associated with Ch3-resistance was expanded between markers SCRI_RS_97417 and JHI-Hv50k-2016-158003 and included 11 SNPs, from which JHI-Hv50k-2016-157070, JHI-Hv50k-2016-156842 had the lowest p-values. These two SNPs were also significant in case of Kr2 isolate. The region on chromosome 2H included 16 loci (7 of them with the lowest p-values were tightly linked to BOPA2_12_11504). Three loci corresponding to this region had suggestive p-values in case of Kr2 tests, so the locus on chromosome 2H may also contribute to resistance to Kr2 isolate. The third region with significant p-value in case of Kr2 tests was identified on chromosome 1H at the locus JHI-Hv50k-2016-33568. Conclusions: Three genomic regions associated with the resistance to one or both isolates of C. sativus were identified via screening of the Siberian spring barley core collection. Comparison of their location with QTLs revealed previously either with biparental mapping populations studies or with GWAS of distinct germplasm and other isolates, demonstrated that resistance to isolates Kr2 and Ch3 is conferred by known spot blotch resistance loci. Information on SNPs related can be used further for development of DNA-markers convenient for diagnostics of resistance-associated alleles in barley breeding programs. [ABSTRACT FROM AUTHOR]

Fusarium crown rot is a major disease of wheat and barley worldwide, with the most frequently isolated causal agents being Fusarium pseudograminearum and F. culmorum. This study has successfully designed a quantitative polymerase chain reaction assay that is specific for F. culmorum, which has been used in conjunction with a previously established F. pseudograminearum-specific assay to compare the location and extent of infection by each fungus across a range of potential hosts, including six winter and three summer cereal species. All common winter cereals, excluding oat, demonstrated a similar range of visual and fungal biomass results when inoculated with either F. pseudograminearum or F. culmorum. Oat exhibited the lowest visual disease ratings and fungal biomass values of the winter cereals, while the sorghum, maize, and rice cultivars returned the lowest values overall. The ranking of host species according to visual discoloration was strongly correlated for both pathogens. Visual reactions to F. pseudograminearum were greater than those caused by F. culmorum in all potential hosts trialed; however, fungal biomass results only indicated this trend for barley. These results demonstrate significant variation in the ability of these pathogens to colonize the range of cereal species examined and also suggest differences between the pathogens in their patterns of host colonization. [ABSTRACT FROM AUTHOR]

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The powdery mildew fungus, Blumeria graminis f. sp. hordei is a worldwide threat to barley (Hordeum vulgare L. ssp. vulgare) production. One way to control the disease is by the development and deployment of resistant cultivars. A genome-wide association study was performed in a Nordic spring barley panel consisting of 169 genotypes, to identify marker-trait associations significant for powdery mildew. Powdery mildew was scored during three years (2012-2014) in four different locations within the Nordic region. There were strong correlations between data from all locations and years. In total four QTLs were identified, one located on chromosome 4H in the same region as the previously identified mlo locus and three on chromosome 6H. Out of these three QTLs identified on chromosome 6H, two are in the same region as previously reported QTLs for powdery mildew resistance, whereas one QTL appears to be novel. The top NCBI BLASTn hit of the SNP markers within the novel QTL predicted the responsible gene to be the 26S proteasome regulatory subunit, RPN1, which is required for innate immunity and powdery mildew-induced cell death in Arabidopsis. The results from this study have revealed SNP marker candidates that can be exploited for use in marker-assisted selection and stacking of genes for powdery mildew resistance in barley. [ABSTRACT FROM AUTHOR]

The purpose of this study is to use near-infrared reflectance (NIR) spectroscopy equipment to nondestructively and rapidly discriminate Fusarium-infected hulled barley. Both normal hulled barley and Fusarium-infected hulled barley were scanned by using a NIR spectrometer with a wavelength range of 1175 to 2170 nm. Multiple mathematical pretreatments were applied to the reflectance spectra obtained for Fusarium discrimination and the multivariate analysis method of partial least squares discriminant analysis (PLS-DA) was used for discriminant prediction. The PLS-DA prediction model developed by applying the second-order derivative pretreatment to the reflectance spectra obtained from the side of hulled barley without crease achieved 100% accuracy in discriminating the normal hulled barley and the Fusarium-infected hulled barley. These results demonstrated the feasibility of rapid discrimination of the Fusarium-infected hulled barley by combining multivariate analysis with the NIR spectroscopic technique, which is utilized as a nondestructive detection method. [ABSTRACT FROM AUTHOR]

Powdery mildew pathogens colonize over 9500 plant species, causing critical yield loss. The Ascomycete fungus, Blumeria graminis f. sp. hordei (Bgh), causes powdery mildew disease in barley (Hordeum vulgare L.). Successful infection begins with penetration of host epidermal cells, culminating in haustorial feeding structures, facilitating delivery of fungal effectors to the plant and exchange of nutrients from host to pathogen. We used expression Quantitative Trait Locus (eQTL) analysis to dissect the temporal control of immunity-associated gene expression in a doubled haploid barley population challenged with Bgh. Two highly significant regions possessing trans eQTL were identified near the telomeric ends of chromosomes (Chr) 2HL and 1HS. Within these regions reside diverse resistance loci derived from barley landrace H. laevigatum (MlLa) and H. vulgare cv. Algerian (Mla1), which associate with the altered expression of 961 and 3296 genes during fungal penetration of the host and haustorial development, respectively. Regulatory control of transcript levels for 299 of the 961 genes is reprioritized from MlLa on 2HL to Mla1 on 1HS as infection progresses, with 292 of the 299 alternating the allele responsible for higher expression, including Adaptin Protein-2 subunit μ AP2M and Vesicle AssociatedMembrane Protein VAMP72 subfamily members VAMP721/722. AP2M mediates effector-triggered immunity (ETI) via endocytosis of plasma membrane receptor components. VAMP721/722 and SNAP33 form a Soluble N-ethylmaleimide-sensitive factor Attachment Protein REceptor (SNARE) complex with SYP121 (PEN1), which is engaged in pathogen associated molecular pattern (PAMP)-triggered immunity via exocytosis.We postulate that genes regulated by alternate chromosomal positions are repurposed as part of a conserved immune complex to respond to different pathogen attack scenarios. [ABSTRACT FROM AUTHOR]

Pyrenophora teres f. teres is the causal agent of net form net blotch (NFNB) of barley. In order to map the genetics of avirulence/virulence in P. teres f. teres , a fungal population was developed using P. teres f. teres isolates BB25 (Denmark) and FGOH04Ptt-21 (North Dakota, USA) due to these two isolates differing in virulence on several common barley lines. 109 progeny isolates were obtained from the BB25 by FGOH04Ptt-21 cross that were then used for NFNB disease evaluation across eight barley lines, four of which have been used commonly as NFNB differential lines as well as four cultivars commonly used in barley production in the Northern Great Plains. BB25 was virulent on one of the barley lines and avirulent on seven of the barley lines whereas, FGOH04Ptt-21 was virulent on all eight barley lines evaluated. Genetic maps were generated with single nucleotide polymorphism (SNP) markers obtained using a restriction associated DNA genotyping by sequencing (RAD-GBS) approach. Sixteen linkage groups were formed and were used to identify quantitative trait loci (QTL) associated with avirulence/virulence. Nine unique QTL were identified on eight linkage groups out of which three QTL had major effects ( R 2 ≥ 45%) while the remaining six QTL were relatively minor ( R 2 < 20%). One or two major effect loci were identified for the lines commonly used as differentials. Conversely, variation in virulence on the local barley cultivars was mostly associated with small effect loci that contributed quantitatively to disease. [ABSTRACT FROM AUTHOR]

Yellowing and dwarfing disease in wheat (Triticum aestivum) and barley (Hordeum vulgaris) plants is a major constraint for yield production worldwide. Wheat and barley strains of wheat dwarf virus (WDV) were found to be associated with the disease in Iran and some parts of the world. However, host specificity of wheat and barley strains of WDV is controversial. In this study, we isolated and sequenced a new variant of WDV from barley plants in the southwest of Iran. The full-length genome of this isolate comprises 2,732 nucleotides with four open reading frames. Sequence analysis of the full-length genome revealed that this isolate is similar (87.3 to 97% identity) to the barley isolates of WDV and was considered as a new variant of the virus. Phylogenetic analysis indicated that this isolate is grouped with other barley isolates of WDV from Europe in a distinct sub-group with a barley isolate from Iran. An infectious clone of WDV was constructed in a binary vector using a partial dimer of the full-length genome. Agroinoculation with the cloned viral DNA resulted in yellowing and dwarfing symptom in both wheat and barley plants. Using this system, the barley isolate of WDV infects wheat and barley with similar efficiency. This infectious clone can be used for screening both wheat and barley plants for resistance/susceptibility, identification of host resistance gene/s and investigating the virus-host interaction. [ABSTRACT FROM AUTHOR]

A new Bacillus amyloliquefaciens subsp. plantarum strain IMV B-7404 was selected by an in-vitro agar plate assay as a potential biological control agent. The strain strongly inhibited the growth of 12 important plant pathogenic fungi. In growth chamber assays, the severity of spot blotch of barley decreased when culture filtrate was applied on leaves or was introduced into the plant growth medium before fungal inoculation. Apparently, the metabolites of strain IMV B-7404 play a role in disease prevention, which indicates that the strain can stimulate induced systemic resistance (ISR). When the cell suspension was sprayed onto leaves, the disease severity depended on environmental and, probably, some other conditions. We suggest that effective biological control by Bacillus-based products depends on spraying leaves with the cell suspension to co-ordinate with the process of plant infection by the pathogen. The ecological behaviour and biology of both the antagonist and the target pathogen are the key elements in enhancing the efficacy of biocontrol products. It is necessary to know the stage of infection that is most vulnerable. This information needs to be identified individually for each pathosystem and in relation to environmental conditions. [ABSTRACT FROM AUTHOR]

Bacterial leaf streak caused by Xanthomonas translucens pv. undulosa (Xtu) is an important disease of wheat (Triticum aestivum) and barley (Hordeum vulgare) worldwide. Transcription activator-like effectors (TALEs) play determinative roles in many of the plant diseases caused by the different species and pathovars of Xanthomonas, but their role in this disease has not been characterized. ICMP11055 is a highly virulent Xtu strain from Iran. The aim of this study was to better understand genetic diversity of Xtu and to assess the role of TALEs in bacterial leaf streak of wheat by comparing the genome of this strain to the recently completely sequenced genome of a U.S. Xtu strain, and to several other draft X. translucens genomes, and by carrying out mutational analyses of the TALE (tal) genes the Iranian strain might harbor. The ICMP11055 genome, including its repeat-rich tal genes, was completely sequenced using single molecule, real-time technology (Pacific Biosciences). It consists of a single circular chromosome of 4,561,583 bp, containing 3,953 genes. Whole genome alignment with the genome of the United States Xtu strain XT4699 showed two major re-arrangements, nine genomic regions unique to ICMP11055, and one region unique to XT4699. ICMP110055 harbors 26 non-TALE type III effector genes and seven tal genes, compared to 25 and eight for XT4699. The tal genes occur singly or in pairs across five scattered loci. Four are identical to tal genes in XT4699. In addition to common repeat-variable diresidues (RVDs), the tal genes of ICMP11055, like those of XT4699, encode several RVDs rarely observed in Xanthomonas, including KG, NF, Y_, YD, and YK. Insertion and deletion mutagenesis of ICMP11055 tal genes followed by genetic complementation analysis in wheat cv. Chinese Spring revealed that Tal2 and Tal4b of ICMP11055 each contribute individually to the extent of disease caused by this strain. A largely conserved ortholog of tal2 is present in XT4699, but for tal4b, only a gene with partial, fragmented RVD sequence similarity can be found. Our results lay the foundation for identification of important host genes activated by Xtu TALEs as targets for the development of disease resistant varieties. [ABSTRACT FROM AUTHOR]

Brazil is blast disease hot spot because severe epidemics have occurred among wheat, triticale, rye, barley and oat crops. Although the first outbreak of barley blast appeared in 1998, little information is available. Therefore, this study aimed to examine host range, mating type composition and population structure of Magnaporthe sp. from a single barley field in São Paulo, Brazil. To examine pathogenicity, 25 Magnaporthe isolates were inoculated on five, three, two and two cultivars of barley, wheat, oat and rice, respectively, and one cultivar each of rye, corn, sorghum, triticale and certain weeds ( Cenchrus echinatus, Setaria geniculata, Brachiaria plantaginea and Eleusine indica). Mating type distribution of 33 isolates was investigated by molecular tools. The genotypic divergence of 41 barley and five wheat isolates was investigated by 15 random amplified polymorphic DNA primers and unweighted pair group method with arithmetic mean. The host range of the barley blast pathogen included wheat, oat, rye and triticale but not rice and weeds. Sexual reproduction appeared to not be involved in the high genotypic diversity because only a single isolate, MAT1-2, was identified. The majority of barley isolates clustered together with wheat blast, except for four, suggesting a different origin. [ABSTRACT FROM AUTHOR]

Pyrenophora teres is an important pathogen of barley. The pathogen has two biotypes: Pyrenophora teres f. teres, which causes the net type of net blotch, and P. teres f. maculata causing the spot type of net blotch. Turkey is an important gene centre of barley and has a rich barley landrace population. Finding disease resistant barley germplasm has potential for world agriculture. Three virulent Pyrenophora teres f. maculata (Ptm) isolates and three virulent Pyrenophora teres f. teres (Ptt) isolates were tested for their pathogenicity to 198 barley landraces, and landraces resistant to both forms of the pathogen were identified. Thirteen landraces (numbered 17, 40, 71, 98, 101, 103, 104, 143, 162, 167, 171, 183 and 185) were resistant to the Ptm isolates and seven (numbered 18, 21, 22, 24, 40, 71 and 153) were resistant to the Ptt isolates. Two landraces (40 and 71) were resistant to all six P. teres isolates. In addition, several of the landraces exhibited reactions to one or two isolates of Ptt or Ptm, in the resistant to moderately resistant range. Using disease resistant host genotypes will help to reduce the use of disease control chemicals, and with development of efficient host resistance strategies to combat net blotch diseases. These landraces could be used as sources of resistance for barley breeding. [ABSTRACT FROM AUTHOR]