Parastagonospora nodorum leaf and glume blotch (syn. Septoria nodorum blotch, SNB) is a severe disease in many wheat-growing areas worldwide. In a previous study, a mapping population, Liwilla × Begra, was used to detect several resistance quantitative trait loci (QTL) at the seedling stage. In this study the same mapping population was analysed at the adult plant stage under field and polytunnel conditions. After artificial inoculation the disease severity on leaves and glumes was scored as the areas under the disease progress curves for field tests and as the percentage of the leaf and glume area covered by necrosis for the polytunnel test. Three QTL associated with Septoria nodorum glume blotch resistance and two QTL associated with Septoria nodorum leaf blotch resistance were detected on chromosomes 1B, 3A, 4A and 7D. Each of the detected QTL explained only a small proportion of the total phenotypic variation, ranging from 9.1 to 20.0%. None of these QTL co-located with necrotrophic effector sensitivity loci or aligned with previously identified resistance loci at the seedling stage for the Liwilla × Begra population. SNB resistance QTL detected in our study did not overlap with QTL associated with morphological and developmental traits. Therefore they could be involved in the defence reaction and can be considered in wheat improvement for SNB resistance.

Powdery mildew is a barley foliar disease that causes great loss in yield. Because of the limited number of effective resistance genes, efforts to identify new sources of resistance are frequently focused on genetically diversified landraces. The goal of this study was to characterise the powdery mildew resistance gene in barley line 2553-3 selected from the Moroccan landrace. Phytopathological testing against a set of differential pathogen isolates revealed different pattern responses of this gene from those of other known resistance genes. F2 and F2:3 (2553-3 × Manchuria) mapping populations were employed to investigate resistance inheritance. Two approaches were applied for the linkage analysis: in the first approach, 22 resistant and 21 susceptible homozygous F2 plants genotyped by the DArTseq platform (Diversity Arrays Technology, Pty. Ltd.) were used; in the second, 94 F2 plants were genotyped by converted DArTseq markers and SSRs. Both analyses delineated a new resistance gene on the short arm of chromosome 2H. The authors propose MlMor as a gene symbol for newly characterized powdery mildew resistance genes in barley line 255-3-3. The results presented herein provide a good foundation for the development of closer linkage markers and MAS breeding.

One of the most important diseases of barley (Hordeum vulgare) is powdery mildew, caused by Blumeria graminis f. sp. hordei. Spring barley line 173‐1‐2 was selected from a Moroccan landrace and revealed broad‐spectrum resistance to powdery mildew. The objective of this study was to map and characterize the gene for seedling powdery mildew resistance in this line. After crossing with the susceptible cultivar ‘Manchuria’, genetic analysis of F2 and F3 families at the seedling stage revealed powdery mildew resistance in line 173‐1‐2 conditioned by a single recessive gene. Molecular analysis of non‐segregating homozygous resistant and homozygous susceptible F2 plants conducted on the DArTseq platform (Diversity Arrays Technology Pty Ltd) identified significant markers which were converted to allele‐specific PCR markers and tested among 94 F2 individuals. The new resistance gene was mapped on the long arm of chromosome 6H. No other powdery mildew recessive resistance gene has been located on 6H so far. Therefore, we concluded that the 173‐1‐2 barley line carries a novel recessive resistance gene designated as mlmr.

The aim of the present study was to validate new simple‐sequence repeat (SSR) markers and use them to assess genetic variability among 24 isolates of Puccinia triticina collected from wheat (Pt‐wheat) and triticale (Pt‐triticale), and 15 isolates of P. recondita f. sp. secalis (Prs) collected from rye. The Pt and Prs isolates were tested for virulence on a set of 35 Thatcher wheat near‐isogenic lines, eight rye lines with known resistance genes, and 53 triticale cultivars with uncharacterized leaf rust resistance. Molecular genotypes were determined using a newly developed set of 34 SSR microsatellite primer pairs. All SSR markers tested on Pt isolates successfully amplified fragments of appropriate size. When tested on the Prs isolates, 21 out of the 34 Pt SSRs amplified expected fragments. Sixteen of these 21 SSRs were polymorphic, providing for the first time microsatellite markers to study genetic variation in Prs. Based on virulence data, variation among Prs isolates was low, probably due to the small number of rye differential lines available. Much higher variation for virulence was observed within the collection of Pt isolates from wheat and triticale, and two separate groups were established with mixed host origin. Substantial genetic variation was detected among the isolates studied with the SSR markers, assuming two different models of SSR evolution (infinite alleles model and stepwise mutation model). The newly developed set of SSR markers proved their effectiveness in detecting genetic variation and should be useful in further population genetics investigations of the two pathogens.

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