Pathogenic Groups Identified Among Isolates of Rhynchosporium secalis

Arabi, M. I. E.; Al-Shehadah, E.; Jawhar, M.

doi:10.5423/ppj.2010.26.3.260

Cited by 7 publications

(10 citation statements)

References 12 publications

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“…However, only about 61 (32 sampled and 29 not sampled) races were present in the populations over the entire survey, accounting for less than a half of the theoretical maximum. There are two likely explanations for this less than expected race richness: 1) although many molecular surveys inferred that sexual recombination could be one of main factors accountable for high genetic variation in R. secalis [9], [10], [12], [17], no sexual stage has yet been observed. Lack of random mating constrained the formation of all races; 2) natural selection coupled with genetic drift eliminated less fit races from the population.…”

Section: Discussionmentioning

confidence: 99%

“…The disease occurs in all of major barley growing regions in the world and can cause significant reductions in barley yield and malting quality [7]. Population genetic studies using molecular and morphological markers reveal that R. secalis , the causal agent of leaf blotch, is a highly variable pathogen [8], [9], [10], possibly attributing to its large effective population size [11], high gene flow [8], [12], high mutation rate [13], [14], frequently sexual reproduction [9] and somatic recombination [15], [16]. These studies also show little genetic differentiation among R. secalis populations collected from the same countries or regions [8], [9], [17], [18].…”

Section: Introductionmentioning

confidence: 99%

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Pathogen Populations Evolve to Greater Race Complexity in Agricultural Systems – Evidence from Analysis of Rhynchosporium secalis Virulence Data

et al. 2012

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Fitness cost associated with pathogens carrying unnecessary virulence alleles is the fundamental assumption for preventing the emergence of complex races in plant pathogen populations but this hypothesis has rarely been tested empirically on a temporal and spatial scale which is sufficient to distinguish evolutionary signals from experimental error. We analyzed virulence characteristics of ∼1000 isolates of the barley pathogen Rhynchosporium secalis collected from different parts of the United Kingdom between 1984 and 2005. We found a gradual increase in race complexity over time with a significant correlation between sampling date and race complexity of the pathogen (r20 = 0.71, p = 0.0002) and an average loss of 0.1 avirulence alleles (corresponding to an average gain of 0.1 virulence alleles) each year. We also found a positive and significant correlation between barley cultivar diversity and R. secalis virulence variation. The conditions assumed to favour complex races were not present in the United Kingdom and we hypothesize that the increase in race complexity is attributable to the combination of natural selection and genetic drift. Host resistance selects for corresponding virulence alleles to fixation or dominant frequency. Because of the weak fitness penalty of carrying the unnecessary virulence alleles, genetic drift associated with other evolutionary forces such as hitch-hiking maintains the frequency of the dominant virulence alleles even after the corresponding resistance factors cease to be used.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Pathogen Populations Evolve to Greater Race Complexity in Agricultural Systems – Evidence from Analysis of Rhynchosporium secalis Virulence Data

et al. 2012

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“…Under inoculation screening experiments in greenhouse and laboratory, the Australian cv. WI2291 proved to be the most susceptible genotype to all scald and spot blotch isolates available so far (Arabi and Jawhar 2004;Arabi et al 2010). Therefore, it was selected for the cDNA-AFLP analysis.…”

Section: Plant Materials and Experimental Designmentioning

confidence: 97%

Transcriptome profiling reveals distinct gene activations in barley responding to scald and spot blotch

Shoaib

Al-Daoude

Arabi

et al. 2018

Cereal Research Communications

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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.

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“…Seedlings were irrigated with Knop's nutrient solution (1 g NaNO 3 ; 0.25 g KNO 3 ; 0.25 g MgSO 4 7H 2 O; 0.25 g KH 2 PO 4 ; and 10 mg FeCl 3 per 1000 ml of water). Inoculation tests of the Rs46 isolate was performed using the method described by Arabi et al (2010). After inoculation, plants were maintained in the dark at 95-100% R.H. for the first 18 h. Non-inoculated control plants were sprayed with distilled water.…”

Section: Host Genotype and Inoculationmentioning

confidence: 99%

“…The most virulent isolate (Rs46) to all barley genotypes available so far (Arabi et al 2010) was used in this study. The fungal mycelia were transferred from a stock culture into Petri dishes containing lima bean agar (LBA) with 13 mg/L kanamycin sulphate and incubated for 2 weeks at 15 ± 1 °C in the dark.…”

Section: Isolation Of Fungusmentioning

confidence: 99%

Transcriptome profile of early responsive genes in susceptible barley duringRhynchosporium secalisinfection

Al-Daoude

Shoaib

Al-Shehadah

et al. 2016

Cereal Research Communications

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Scald caused by Rhynchosporium secalis, is an economically important disease found worldwide. In order to profile genes and pathways responding to R. seclais infection, leaf transcriptomes before and after fungus inoculation in susceptible barley were compared using cDNA-AFLP technique. Transcriptional changes of 144 expressed sequence tags (ESTs) were observed, of which 18 have no previously described function. Functional annotation of the transcripts revealed a wide range of pathways including cell wall fortification, cytoskeleton construction and metabolic processes at different time points. Furthermore, the results of RT-PCR analysis on candidate genes, ABC transporters and lycine-specific demethylase were consistent with the cDNA-AFLP data in their expression patterns. Taken together, our data suggest that susceptible barley reprograms metabolic and biological processes to initiate a suitable response R. secalis infection.

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Pathogenic Groups Identified Among Isolates of Rhynchosporium secalis

Cited by 7 publications

References 12 publications

Pathogen Populations Evolve to Greater Race Complexity in Agricultural Systems – Evidence from Analysis of Rhynchosporium secalis Virulence Data

Pathogen Populations Evolve to Greater Race Complexity in Agricultural Systems – Evidence from Analysis of Rhynchosporium secalis Virulence Data

Transcriptome profiling reveals distinct gene activations in barley responding to scald and spot blotch

Transcriptome profile of early responsive genes in susceptible barley duringRhynchosporium secalisinfection

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