Pille Sooväli

A spelt diversity panel including 80 genotypes of winter spelt was tested for resistance to common bunt, leaf blotch, powdery mildew, leaf rust, stem rust and yellow rust. The reaction to diseases was investigated in field trials carried out at multiple European locations between 2013 and 2019. Resistance was assessed after artificial inoculation or natural infestation by visual scoring of symptoms. The presence of rust resistance genes was postulated using molecular markers. It was found that the presence of hulls plays a role as a passive resistance factor against common bunt. The risk of fungal diseases in spelt is not negligible. Genotypes with low disease severity in all environments as well as combined resistance to multiple diseases were determined. Across all test environments, spelt genotypes ʻSofia 1ʼ and ʻAlbinʼ showed a very low disease infestation by common bunt, ʻSofia 1ʼ, ʻRiniken Weißkornʼ, ʻZürcher Oberländer Rotkornʼ and ʻToess 5Bʼ by leaf blotch, ʻSpeltvete från Gotlandʼ by yellow rust and ʻSofia 1ʼ by leaf rust and stem rust. The influence of the breeding period was examined, and differences between modern and old varieties/landraces have not been proven. The results obtained can be used for the selection of suitable parental material for breeding spelt with improved disease resistance.

Oat sterile dwarf virus (OSDV) is a fijivirus whose genome segments 7 to 10 were sequenced earlier. In the current study, the complete genome was sequenced. To confirm the genome ends, rapid amplification and sequencing of cDNA ends were performed. The complete OSDV genome consists of 10 double-stranded RNA (dsRNA) segments with a total size of 28,686 bp. The sense strand sequence of all segments has the terminal consensus sequence motif 5’-AACGA(5–7)… U(6–8)(A/U)GUC-3’, in which the length of the stretches of A and U varies, being slightly shorter for segments 1–4 and longer for segments 5–10. The 3’ end of segment 3 is …UGUC, not AGUC as in the other segments. Segments 5, 7, and 10 contain two small ORFs, while each of the other segments contains one long ORF. ORF7-2 and ORF9 are slightly longer than annotated before. Phylogenetic analysis based on amino acid sequences of the RNA-directed RNA polymerase (RdRP) placed OSDV between the plant fijiviruses and Nilaparvata lugens reovirus (NLRV), an insect fijivirus that does not replicate in plants. OSDV RdRP shares 48–49% sequence identity with other plant-infecting fijivirus RdRPs and 30% identity with that of NLRV. OSDV has earlier been reported in several Northern and Central European countries. The sequencing of the complete genome serves as a reference for identifying all segments in future high-throughput sequencing datasets, enabling the investigation of the molecular epidemiology and evolution of OSDV.

Efficacy of the fungicide tebuconazole was tested in 2 treatment regimes in 3 spring barley varieties over three years (2003–2005). The impact of the fungicide on the control of major barley pathogens Pyrenophora teres and Cochliobolus sativus, as well as kernel yield was studied in the course of field trials. The fungicide treatments had a strong impact on the control of infection of P. teres and increased kernel yield in variable disease infection conditions. For the more resistant genotype, fungicide application had relatively low returns because of the much higher level of biological resistance and small disease-related yield reductions. For the susceptible genotype, severe disease infection caused bigger yield reduction, not compensated by the use of fungicides. Use of fungicide demonstrated the highest economic return in the case of the moderately susceptible barley variety.;