Pyrenophora teres f. maculata (Ptm) is a fungal pathogen that causes the spot form of net blotch on barley and leads to economic losses in many of the world's barley-growing regions. Isolates of Ptm ...exhibit varying levels of aggressiveness that result in quantifiable changes in the severity of the disease. Previous research on plant-pathogen interactions has shown that such divergence is reflected in the proteome and secretome of the pathogen, with certain classes of proteins more prominent in aggressive isolates. Here we have made a detailed comparative analysis of the secretomes of two Ptm isolates, GPS79 and E35 (highly and mildly aggressive, respectively) using a proteomics-based approach. The secretomes were obtained in vitro using media amended with barley leaf sections. Secreted proteins therein were harvested, digested with trypsin, and fractionated offline by HPLC prior to LC-MS in a high-resolution instrument to obtain deep coverage of the proteome. The subsequent analysis used a label-free quantitative proteomics approach with relative quantification of proteins based on precursor ion intensities. A total of 1175 proteins were identified, 931 from Ptm and 244 from barley. Further analysis revealed 160 differentially abundant proteins with at least a two-fold abundance difference between the isolates, with the most enriched in the aggressive GPS79 secretome. These proteins were mainly cell-wall (carbohydrate) degrading enzymes and peptidases, with some oxidoreductases and other pathogenesis-related proteins also identified, suggesting that aggressiveness is associated with an improved ability of GPS79 to overcome cell wall barriers and neutralize host defense responses.
Net blotch foliar diseases of barley are important in Turkey, lowering grain yields and quality. There are two forms, the spot form (caused by Pyrenophora teres f. maculata (Ptm)) and the net form ...(caused by P. teres f. teres (Ptt)). To determine the pathotypes of Ptt and Ptm in Turkey, surveys were carried out during 2012, 2013 and 2015. Pyrenophora teres samples were collected from 34 provinces of Turkey. From these samples, 258 Ptm and 167 Ptt single conidium isolates were obtained. Pathotypes of 50 P. teres f. maculata and 40 P. teres f. teres isolates were assessed by inoculating onto a differential set of 25 barley genotypes. Twenty six Ptm pathotypes and 24 Ptt pathotypes were identified, and significant pathogenic variation was found among the isolates. Barley breeding programmes in Turkey should consider the pathotypes identified for incorporation of net blotch resistance. Continuous virulence monitoring for the P. teres population should be carried out to inform resistance breeding priorities.
Wild barley (Hordeum spontaneum) and barley landraces are important sources of genetic variation for disease resistance. Thirty wild barley (H. spontaneum) genotypes and 30 barley landraces were ...evaluated for susceptibility to two Drechslera graminea isolates. Virulence differences were observed between the isolates, while the responses of the host genotypes to the isolates also varied. Of the H. spontaneum genotypes, 23% and 63%, respectively, were resistant to the Yozgat D. graminea isolate, and Eskişehir D. graminea isolates. On the other hand, 43% and 90% of the barley landraces were resistant to Yozgat and Eskişehir D. graminea isolates, respectively. Hordeum spontaneum genotypes 13, 24, 27, 29, 54, 86, and 91 exhibited resistance to both D. graminea isolates, while genotypes 14 and 32 showed intermediate reactions to the Yozgat isolate and resistant reactions to the Eskişehir isolate. Barley landraces 21, 37, 38, 39, 40, 73, 98, 128, 139, 153, 159,167, and 171 showed resistant reactions, and barley landrace 8 showed an intermediate reaction to both isolates. Barley landraces 3, 20, 24, 71, 101, 103, 104 and 160 exhibited intermediate responses to the Yozgat isolate and a resistant response to the Eskişehir isolate. Using resistant barley genotypes would reduce the need for pesticides for control of leaf stripe, and be an environmentally preferred strategy for disease control. The disease resistance present in wild barley and barley landraces are important for expanding the genetic basis of cultivated barley (H. vulgare). The resistant and intermediate genotypes identified in this study could be used as resistance sources in barley breeding, or landraces could be used directly for commercial barley production.
In this study, we present the existence result for the the second order
m
-point boundary value problems on infinite time scales. Nagumo condition, lower and upper solutions play an important role in ...the arguments.
Powdery mildew, net blotch, scald, spot blotch, barley stripe, and leaf rust are important foliar fungal pathogens of barley. Fungal leaf pathogens negatively affect the yield and quality in barley ...plant. Virulence changes, which can occur in various ways, may render resistant plants to susceptible ones. Factors such as mutation, population size and random genetic drift, gene and genotype flow, reproduction and mating systems, selection imposed by major gene resistance, and quantitative resistance can affect the genetic diversity of the pathogenic fungi. The use of fungicide or disease-resistant barley genotypes is an effective method of disease control. However, the evolutionary potential of pathogens poses a risk to overcome resistance genes in the plant and to neutralize fungicide applications. Factors affecting the genetic diversity of the pathogen fungus may lead to the emergence of more virulent new pathotypes in the population. Understanding the factors affecting pathogen evolution, monitoring pathogen biology, and genetic diversity will help to develop effective control strategies.
Key message
Rhynchosporium commune
is a globally devastating pathogen of barley. Wild and landrace barley are underutilized, however, contain an abundance of loci that can be used as potential ...sources of resistance.
Rhynchosporium commune,
the causal agent of the disease scald or leaf blotch of barley, is a hemibiotrophic fungal pathogen of global importance, responsible for yield losses ranging from 30 to 40% on susceptible varieties. To date, over 150 resistance loci have been characterized in barley. However, due to the suspected location of the
R. commune
host jump in Europe, European germplasm has been the primary source used to screen for
R. commune
resistance leaving wild (
Hordeum spontaneum
) and landrace (
H. vulgare
) barley populations from the center of origin largely underutilized. A diverse population consisting of 94 wild and 188 barley landraces from Turkey were genotyped using PCR-GBS amplicon sequencing and screened with six Turkish
R. commune
isolates. The isolates were collected from distinct geographic regions of Turkey with two from the Aegean region, two from central Turkey and two from the Fertile Crescent region. The data set was utilized for association mapping analysis with a total of 21 loci identified, of which 12 were novel, indicating that these diverse primary barley gene pools contain an abundance of novel
R. commune
resistances that could be utilized for resistance breeding.
By employing Green's function, we obtain new Lyapunov and Hartman-type inequalities for higher-order discrete fractional boundary value problems. Reported results essentially generalize some theorems ...existing in the literature. As an application, we discuss the corresponding eigenvalue problems.
Rhynchosporium commune is the causal agent of barley scald disease and is an important foliar disease of barley worldwide. During 2012, 2013, and 2014, Rhynchosporium commune single-spore isolates ...were collected from different parts of Turkey, and from those, 60 isolates were selected. The mating type distribution and prevalence of these selected isolates were determined. Twenty-one of the 60 single-spore isolates were found to be MAT1-1 type and 39 isolates were MAT1-2 type χ2 (1:1) types = 5.40 (P = 0.02). The mating type ratio showed that R. commune populations may have predominantly asexual reproduction in Turkey. To determine the genetic diversity of R. commune isolates, 5 single-spore isolates from different regions of Turkey were tested with 72 ISSR primers. Eleven primers were found to be polymorphic. UBC 826, UBC 861, UBC 886, UBC 887, UBC 890, UBC 848, UBC 884 and UBC 850 primers showed optimal band numbers and good band intensities. Sixty isolates were evaluated with these 8 ISSR primers. UBC826 and UBC886 primers amplified the largest numbers of bands. The genetic diversity of the isolates in the R. commune population in Turkey appeared to be low. There were no definite groupings of the mating type or geographical region. Turkey is one of the gene centers of barley and this study is the first one addressing the genetic variation and mating type distribution of R. commune in Turkey. The low genetic diversity and possible asexual reproduction observed in our study may contribute to the hypothesis that R. commune did not evolve in the origin of the barley plant.
•This study is the first one addressing the genetic variation and mating type distribution of Rhynchosporium commune in Turkey.•Twenty-one of the 60 single-spore isolates were found to be MAT1-1 type and 39 isolates were MAT1-2 type (χ2 (1:1) types = 5.40 and P = 0.02).•UBC826 and UBC886 primers amplified the largest numbers of bands.•There were no definite groupings of the mating type or geographical region.•Low genetic diversity and possible asexual reproduction observed in this study.•Our results may contribute to hypothesis that R. commune did not evolve in the origin of the barley plant.
Unimproved landraces and wild relatives of crops are sources of genetic diversity that were lost post domestication in modern breeding programs. To tap into this rich resource, genome-wide ...association studies in large plant genomes have enabled the rapid genetic characterization of desired traits from natural landrace and wild populations. Wild barley (Hordeum spontaneum), the progenitor of domesticated barley (Hordeum vulgare), is dispersed across Asia and North Africa, and has co-evolved with the ascomycetous fungal pathogens Pyrenophora teres f. teres and P. teres f. maculata, the causal agents of the diseases net form of net blotch and spot form of net blotch, respectively. Thus, these wild and local adapted barley landraces from the region of origin of both the host and pathogen represent a diverse gene pool to identify new sources of resistance, due to millions of years of co-evolution. The barley-P. teres pathosystem is governed by complex genetic interactions with dominant, recessive, and incomplete resistances and susceptibilities, with many isolate-specific interactions. Here, we provide the first genome-wide association study of wild and landrace barley from the Fertile Crescent for resistance to both forms of P. teres. A total of 14 loci, four against P. teres f. maculata and 10 against P. teres f. teres, were identified in both wild and landrace populations, showing that both are genetic reservoirs for novel sources of resistance. We also highlight the importance of using multiple algorithms to both identify and validate additional loci.
PDF
