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Eyespot is a major fungal disease of winter wheat, mostly affecting the base of the stem. The development of biological control approaches, using organisms such as earthworms, represents a potential alternative strategy for eyespot control. In a greenhouse experiment, we analyzed the response of two wheat cultivars (Soissons and Aubusson) to the presence of the pathogenic fungus Oculimacula yallundae and the anecic earthworm Lumbricus terrestris , alone and in combination. We assessed necrosis frequency, necrosis severity, wheat biomass, resource allocation and soil mineral concentrations. Disease incidence was lower in the presence of earthworms: the frequency of necrosis was 44% lower for Soissons and 70% lower for Aubusson. Necrosis severity was also lower for both cultivars (50% lower for Soissons and 80% lower for Aubusson) in the presence of earthworms. Earthworms had no detectable effect on the shoot and root biomasses of plants exposed to the fungus, but they modified resource allocation between plant organs and nutrient translocation within the plant. Our results suggest that earthworms are a potentially effective biocontrol agent for eyespot, and we discuss the possible underlying mechanisms. [ABSTRACT FROM AUTHOR]

Endopeptidase marker EpD1b and STS marker XustSSR2001-7DL are closely linked to very effective eyespot resistance gene Pch1. Because of this, the aim of this study was to compare the results obtained under lab conditions using such markers with the results obtained under field conditions. 134 wheat breeding lines and Triticum aestivum L. var. Randevous used as a eyespot resistance control were analized. The combination of three methods allowed to select eight completely resistant or high resistant lines, that could be used in following breeding processes. Results obtained using endopeptidase and STS markers in 100% correlate with the phenotyping scoring. [ABSTRACT FROM AUTHOR]

The endopeptidase marker Ep-D1b and Sequence Tag Site (STS) marker XustSSR2001–7DL were reported to be closely associated with the most effective resistance gene ( Pch1) in wheat ( Triticum aestivum L.) for strawbreaker foot rot [ Pseudocercosporella herpotrichoides (Fron) Deighton]. Our objectives were to: (i) develop an efficient assay method for Ep-D1b in wheat; (ii) correlate endopeptidase zymograms to strawbreaker foot rot reactions of various wheat genotypes; and (iii) compare the utility of Ep-D1b and XustSSR2001–7DL for predicting disease response. An improved method of assaying for the Ep-D1b marker using roots from a single seedling was developed, which is a 2.5-fold improvement over the previous method. Thirty-eight wheat genotypes with known reactions to strawbreaker foot rot were analysed for Ep-D1b and the STS marker. Six distinct endopeptidase zymograms were identified among these 38 genotypes tested, and three of these patterns were novel. The endopeptidase marker was 100% accurate for predicting strawbreaker foot rot disease response, whereas the STS marker predicted the correct phenotype with approximately 90% accuracy. The endopeptidase marker Ep-D1b was more effective and was more economical for use in marker-assisted selection strategies for Pch1 in our laboratory compared with the STS marker. [ABSTRACT FROM AUTHOR]

After 10 years of evaluation in different locations with high levels of incidence of disease, a group of sugarcane somaclones derived from callus tissues was selected for eyespot resistance. Resistance evaluations of four somaclones were performed under field and laboratory conditions. The results confirmed the superiority of two somaclones, one resistant and one tolerant to eyespot disease. Restriction analysts of mitochondrial DNA revealed that the two somaclones had a different DNA organization which distinguished them both from each other and from the donor plant, the restriction profile was similar however to that of the resistant control done. Restriction patterns of a third somaclone, also resistant, were similar to those of the donor plant. Differences among the somaclones were also evident when using a maize ribosomal DNA probe. [ABSTRACT FROM AUTHOR]

Resistance to Pseudocercosporella herpotrichoides in five wheat cultivars, accession W6 7283 of Dasypyrum villosum, and Chinese Spring disomic addition lines of the D, villosum chromosomes 1V, 2V, 4V, 5V, 6V and 7V, was evaluated in seedlings by measuring disease progress 6 weeks after inoculation with a figlucuronidase-transformed strain of the pathogen and by visual estimates of disease severity. D, villosum and the disomic addition line of chromosome 4V were as resistant as wheat cultivars 'VPM-1 ' and 'Cappelle I)esprez', but less resistant than 'Rendezvous'. Resistance of the chromosome 4V disomic addition line was equivalent to that of D. villosum. 'Chinese Spring' and disomic addition lines of 1V, 2V, 5V, 6V and 7V were all susceptible, These results confirm SPRAGUF's (1936) report of resistance in D. villosum to P. herpotrichoides and establish the chromosomal location for the genes controlling resistance. The presence of chromosome 4V in the addition line and its homoeology to chromosome 4 in wheat were confirmed by Southern analysis of genomic DNA using chromosome group 4-specific clones. This genetic locus is not homoeologous with other known genes for resistance to P. herpotrichoides located on chromosome group 7, and thus represents a new source of resistance to this pathogen. [ABSTRACT FROM AUTHOR]

Eyespot disease, caused by Pseudocercosporella herpotrichoides, can be devastating to winter wheat grown in northern Europe and the northwest USA. Accessions from eight different tetraploid wheat species randomly extracted from core collections were scored for resistance to eyespot disease using a β-glucuronidase (GUS)-transformed strain of P. herpotrichoides. The GUS values for the combined population followed a quasi-Gaussian distribution. Three species, Triticum dicoccoides, T. durum and T. turanicum, showed significant variation (P < 0.001) in disease response with T. dicoccoides having the lowest disease scores, i.e. highest levels of resistance. All tetraploid accessions were less resistant than resistant diploid T. tauschii accessions. Thirteen percent of tetraploid accessions had disease scores that ranged between the average of the resistant accessions of T. tauschii and the moderately resistant hexaploid germplasm line Cerco. Eight accessions (three accessions of T. dicoccoides, two of T. turgidum and three of T. durum) with low disease scores (resistance) to infection were selected for further genetic analysis. [ABSTRACT FROM AUTHOR]

Gene Pch1, which confers resistance to eyespot disease ( Pseudocercosporella herpotrichoides Fron), has been located on chromosome 7D in the H-93 wheat- Aegilops ventricosa transfer lines using isozyme markers and DNA probes corresponding to group 7 chromosomes. Previous experiments had failed to ascertain this location. The lack of segregation of the resistance trait in progeny from reciprocal crosses between lines H-93-70 and VPM1 indicates that their respective resistance factors are allelic. Line H-93-51 carries the endopeptidase allele Ep-D1b but is susceptible to eyespot, which indicates that resistance to eyespot is not a product of the Ep-D locus, as had been proposed in a previous hypohesis. [ABSTRACT FROM AUTHOR]

The taxonomy of Oculimacula, Rhynchosporium and Spermospora is re-evaluated, along with that of phylogenetically related genera . Isolates are identified using comparisons of DNA sequences of the internal transcribed spacer ribosomal RNA locus (ITS), partial translation elongation factor 1-alpha ( tef1 ), actin ( act ), DNA-directed RNA polymerase II largest ( rpb1 ) and second largest subunit ( rpb2 ) genes, and the nuclear ribosomal large subunit (LSU), combined with their morphological characteristics. Oculimacula is restricted to two species, O. acuformis and O. yallundae , with O. aestiva placed in Cyphellophora , and O. anguioides accommodated in a new genus, Helgardiomyces . Rhynchosporium s. str . is restricted to species with 1-septate conidia and hooked apical beaks, while Rhynchobrunnera is introduced for species with 1-3-septate, straight conidia, lacking any apical beak. Rhynchosporium graminicola is proposed to replace the name R. commune applied to the barley scald pathogen based on nomenclatural priority. Spermospora is shown to be paraphyletic, representing Spermospora (type: S. subulata ), with three new species, S. arrhenatheri, S. loliiphila and S. zeae , and Neospermospora gen. nov . (type: N. avenae ) . Ypsilina (type: Y. graminea ), is shown to be monophyletic, but appears to be of minor importance on cereals. Finally , Vanderaaea gen. nov . (type: V. ammophilae ), is introduced as a new coelomycetous fungus occurring on dead leaves of Ammophila arenaria . Citation: Crous PW, Braun U, McDonald BA, Lennox CL, Edwards J, Mann RC, Zaveri A, Linde CC, Dyer PS, Groenewald JZ (2020). Redefining genera of cereal pathogens: Oculimacula , Rhynchosporium and Spermospora . Fungal Systematics and Evolution 7: 67-98. doi: 10.3114/fuse.2021.07.04., (© 2021 Westerdijk Fungal Biodiversity Institute.)