Combination of seedling and adult plant resistance to leaf scald for stable resistance in barley

Abstract

Rhynchosporium secalis can overcome a single resistance gene of barley in a relatively short period of time. Novel genes and quantitative trait locis (QTLs) are therefore vital to control scald in barley. A population of 220 double haploid lines was developed from a cross of Vlamingh and WABAR2147, where Vlamingh showed adult plant resistance (APR) and WABAR2147 showed seedling resistance to a group of isolates. The population was tested for APR to scald under natural infection in two consecutive seasons in addition to a seedling screen with three isolates. One single gene was mapped to chromosome 6H based on the seedling test, and two QTLs (QSc.VlWa.4H and QSc.VlWa.6H) were mapped to chromosomes 4H and 6H based on APR. Epistatic interaction was observed between the two QTLs, and environment/QTL interaction was only observed for QSc.VlWa.6H which cosegregated with the seedling resistance gene and contributed to basal resistance against scald during whole growth stages. QSc.VlWa.4H explained 42.5 and 57.8 % of the phenotypic variation in the two independent trials when the effect of QSc.VlWa.6H was excluded from the analysis. We developed a high-density consensus genetic map with 7,876 molecular makers and anchored 43 QTLs and 7 genes for scald resistance from different mapping populations. No known QTLs or genes were reported in a similar position to QSc.VlWa.4H, and it was the first major QTL for APR of scald on chromosome 4HS in barley. Combination of the two QTLs achieved better and stable scald resistance across four different environments.

Characterisation of barley resistance to rhynchosporium on chromosome 6HS

“…Previous studies have identified multiple QTL conferring resistance to rhynchosporium on the distal end of chromosome 6H (Jensen et al 2002;Cheong et al 2006;Shtaya et al 2006;Wagner et al 2008;Wang et al 2014). While Cheong et al (2006) suggested that rhynchosporium resistance identified on 6HS in a Schooner/O'Connor population could be a new locus independent of Rrs13, due to the difficulty of comparing genetic maps and sparsity of molecular markers it was not clear whether this and other QTL represented alleles of Rrs13 or an entirely different resistance locus.…”

“…The QTL identified by Cheong et al (2006) was found using natural inoculum, and the position of the QTL peak (at marker ABG378), strongly suggests that the QTL effect represents an allele of Rrs18. A single major resistance gene identified in a Vlamingh x WABAR2147 DH population by Wang et al (2014) on 6HS has flanking markers 1_1166 and Bmag500, located at 7.47 Mb and 16.14 Mb respectively, putting this QTL also in the vicinity of Rrs18. The resistance gene on 6HS in WABAR2147 was shown to be effective irrespective of growth stage, so if the conclusion that this resistance is an allele of Rrs18 is correct, it would suggest that Rrs18 would provide an effective resistance in the field (Wang et al 2014).…”

“…x WABAR2147 DH population by Wang et al (2014) on 6H has flanking markers 1_1166 as distal marker and Bmag500 as proximal marker, clearly indicating the presence of a single major resistance gene outside the Rrs13 interval. In most of these publications, markers are very sparse, and the use of different marker sets makes comparing the genetic maps difficult or impossible.…”

Identification and Fine Mapping of a White Husk Gene in Barley (Hordeum vulgare L.)

“…SSR markers flanking the target gene were first integrated into the barley consensus map [ 35 ]. Sequences of the molecular markers in the regions were used to search the barley genomic database ( http://webblast.ipk-gatersleben.de/barley/viroblast.php ) to identify corresponding barley contigs.…”

Phenotypic Characterization of Canadian Barley Advanced Breeding Lines for Multiple Disease Resistance

“…This high variability gives it an advantage to quickly overcome the resistance of individual genes in barley in a relatively short period (Zhan et al 2008). To effectively control barley scald, continuous efforts on identification of novel genes and quantitative trait loci (QTLs) are therefore vital to keep pace with pathogen development (Wang et al 2014).…”