Abstract Random samples of spores of wheat powdery mildew were collected from the atmosphere by means of a jet spore sampler while driving through selected wheat growing areas in Europe in 1986. Their single colony progenies were tested in the laboratory forvirulence against wheat differential varieties with powdery mildew resistances Pm2, Pm4b, Pm8, Mli and the combinations Pm2+Pm6, Pm4b+Pm8 and Pm2+Pm4b+Pm8. There were regional differences in virulence frequencies. Virulence on Pm2, Pm2+Pm6 and, less expressed, on Pm4b was most frequent in England and decreased mainly to the east, whereas the reverse was true for Pm8. Virulence to Mli was generally high, and to the combined genotypes generally low. The results suggest that large parts of Europe are an epidemiological unit. The data are discussed with respect to selection caused by the varieties grown, as well as to the influence of wind distribution on the composition of the pathogen population.
The prevalence of R hizoctonia spp. in European soils was determined by analysing soil samples from 282 locations. R hizoctonia spp. were found in 68% of these samples from France, Germany, the UK , Poland, Italy, Spain, Hungary and the Czech Republic. Samples from 136 locations were further analysed by pyrosequencing. Seventy‐six percent of the isolates were R hizoctonia solani and 24% binucleate R hizoctonia spp. Rhizoctonia solani anastomosis group ( AG ) 5 was detected most frequently (25%), followed by AG 9 (16%) and AG 4 (13%). For the binucleate Rhizoctonia spp., AG E was most prevalent (13%). Rhizoctonia cerealis was not detected in soil samples. Soil type or cropping history had no effect on the type of Rhizoctonia observed. Rhizoctonia solani AG 5 was the most frequently detected AG irrespective of the previous crop. The spectrum of AG s detected was similar for France, Germany and Poland but was significantly different for the UK ( P = 0·0016). Finally, the baseline sensitivity towards sedaxane, a new active ingredient for seed treatment, was analysed for all isolates. The results indicate a low baseline sensitivity (average EC 50 of 0·028 p.p.m.) for all Rhizoctonia AG s. No difference in sensitivity was observed with the isolates obtained from different countries.
A pathogenicity survey of Puccinia recondita f.sp. tritici ( Prt ) was conducted in western Europe in 1995. Random urediospore isolates (850) of Prt were collected from the air by means of a jet spore sampler in wheat‐growing regions of Austria, Belgium, France, Germany, northern Italy, Switzerland and the UK. Pathogenicity of the isolates was determined in tests of detached primary leaf segments maintained on water agar supplemented with benzimidazole (35 p.p.m.). The differential genotypes used were Thatcher, 20 near‐isogenic Thatcher lines each with a single leaf rust resistance gene, and five cultivars/lines with additional resistance genes. All isolates were avirulent for the genes Lr9, Lr19, Lr21, Lr24, Lr25 and Lr29 , and both virulence and avirulence were detected for the remaining 19 genes. Fifty‐three pathotypes were identified, four of which predominated (64% of isolates) and were widespread throughout western Europe. Three of the four predominant pathotypes were also identified in collections of wheat leaf rust collected in Poland, Hungary, Estonia and Finland. One pathotype, which comprised 35% of isolates in the south of France, was not detected in any other region. This pathotype was indistinguishable from several isolates obtained from Morocco, which suggested that it may have originated from northern Africa. Comparisons with previously published data suggested that the four predominant pathotypes were very similar and possibly the same as pathotypes present in the former Czechoslovakia for up to 20 years. The results obtained provide evidence of migration of Prt over considerable distances in western Europe, stressing the need for a co‐ordinated approach for genetical control of the disease in this region.
Um Kandidatengene fur die metabolische Herbizid-Resistenz zu erfassen, wurde mithilfe eines „Transcriptomics“-Ansatz ein quantitativer Vergleich der Genexpression zwischen sensitiven und resistenten Biotypen des Acker-Fuchsschwanzs (ALOMY) durchgefuhrt. Ausgehend von einem metabolisch resistenten Biotyp wurde im ersten Schritt mithilfe eines „paired-end“ RNA-Seq Protokolls ein Referenz-Transkriptom fur ALOMY aus unbehandelten und Herbizid-behandelten Pflanzen erstellt. Im zweiten Schritt wurde die Genexpression in verschiedenen metabolisch resistenten ALOMY-Biotypen sowie in einer reprasentativen Auswahl an sensitiven Wildtyp-Biotypen mithilfe einer 3´-spezifischen RNA-Sequenzierung bestimmt und mit dem Referenztranskriptom abgeglichen. Durch Vergleich der Expressionshohe einzelner Gene in Wildtyp und resistenten ALOMY Biotypen wurden Kandidatengene aus der Gruppe der Glutathion-Transferasen identifiziert. Weitere Analysen werden notwendig sein, um eine enge Korrelation mit der metabolischen Resistenz zu verifizieren. Stichworter: ALOMY, Acker-Fuchsschwanz, Glutathion S-Transferase, MACE, metabolische Resistenz, Referenztranskriptom Molecular analysis of metabolic resistance in blackgrass Abstract A transcriptomics approach was chosen in order to determine candidate genes for metabolic herbicide resistance in a quantitative comparison of expressed genes in sensitive wild type and resistant blackgrass (Alopecurus myosuroides = ALOMY) plants. Firstly a reference transcriptome for blackgrass was established by means of a paired-end RNA-Seq protocol prepared from control and herbicide treated plants from a metabolic resistant biotype. Secondly gene expression was measured in different metabolic resistant ALOMY biotypes and a representative selection of sensitive wild type plants using a 3´-specific RNA sequencing strategy and related to the reference transcriptome. By comparing expression levels for individual genes in wild type and resistant blackgrass biotypes candidate genes from the group of glutathione transferases were identified. Further analyses will be necessary in order to verify a close correlation with the metabolic resistance. Keywords: ALOMY, blackgrass, MACE, non-target site resistance, reference transcriptome, RNA-Seq
