Identifying potential novel resistance to the foliar disease ‘Scald’ (Rhynchosporium commune) in a population of Scottish Bere barley landrace (Hordeum vulgare L.)

Abstract

Barley ‘Scald’ is an economically damaging fungal disease that is a global problem, causing significant yield and economical losses in the UK barley feed and malting industries. Presently, a limited number of Rhynchosporium resistance genes exist, but selective pressures on the fungi cause the demand for new sources of resistance. Landraces, such as the Scottish Bere barley, hold potential sources of resistance that can be utilised, with farmers providing anecdotal evidence of resistance in field populations of Bere. This study analysed 131 heritage cultivars and landrace lines, including 37 Bere lines, to screen for resistance using both detached leaf assays (DLAs) and field experiments. Results showed that Bere lines produced smaller, but more necrotic, lesions for the majority of isolates in the DLAs, as well as smaller scores when visually assessed in field conditions. Whilst the infection patterns of the lines differed between isolates and experimental conditions, three Bere lines were identified as consistently showing reduced levels of infection (45 A 23, 58 A 36 Eday, and 8-125). Using genome-wide association analysis, we were able to identify a number of genomic regions associated with reduced infection symptoms, four in regions associated with known resistance genes, but another four associated with new regions that contain promising candidate genes. Further analysis of these new regions and candidate genes should be undertaken to identify targets for future disease-resistance breeding.

Evaluating Variation in Germination and Growth of Landraces of Barley (Hordeum vulgare L.) Under Salinity Stress

“…Trials were grown in a climate-controlled glasshouse with a day/night temperature of 15/18°C and supplementary lighting (at 200 μmol quanta m –2 s –1 ) provided when light intensity was less than 200 W m –2 and shading when above 450 Wm –2 to give a day length of 16 h [as outlined in Cope et al (2021) ]. Relative humidity was not controlled.…”

Wild barley (Hordeum spontaneum) and landraces (Hordeum vulgare) from Turkey contain an abundance of novel Rhynchosporium commune resistance loci

“…A recent study used nested association mapping in the HEB-25 wild barley population crossed to the German line 'Barke' identifying eight loci (Büttner et al 2020). In addition, association mapping within the Scottish 'Bere' landrace barley population, used due to the suspected Northwestern Europe origin of R. commune, also identi ed eight loci (Cope et al 2021). The work by Clare et al (2021) recently demonstrated that despite low marker density, novel resistance/susceptibility loci against fungal pathogens with complex host-pathogen genetic interactions can be identi ed by association mapping using natural wild and landrace barley populations.…”

Genome-Wide Association Study for Resistance to Rhynchosporium in a Diverse Collection of Spring Barley Germplasm

“…Indeed, GWAS can access considerable diversity and numerous historic recombination events, which results in reduced linkage disequilibrium (LD), providing greater mapping resolution [18]. Recently this approach has been used in a number of studies to identify resistance loci in barley [15,19,20]. In European spring barley germplasm, the Rrs1 Rh4 locus was shown to be the main contributor to resistance, with a further 15 resistance QTL showing minor effects [9].…”

“…In a collection of Ethiopian, North American, and the International Center for Agricultural Research in the Dry Areas (ICARDA) barley lines, multiple resistance QTL were found with 17 marker-trait associations (MTA) in 16 genomic regions [19]. The value of Scottish bere barley landraces to mine for rhynchosporium resistance genes was also pointed out and eight genetic regions associated with resistance were identified [20]. These studies used three, five, and two field trials, respectively, for their GWAS analysis.…”