Genetic mapping of a barley leaf rust resistance gene Rph26 introgressed from Hordeum bulbosum

Abstract

The quantitative barley leaf rust resistance gene, Rph26, was fine mapped within a H. bulbosum introgression on barley chromosome 1HL. This provides the tools for pyramiding with other resistance genes. A novel quantitative resistance gene, Rph26, effective against barley leaf rust (Puccinia hordei) was introgressed from Hordeum bulbosum into the barley (Hordeum vulgare) cultivar 'Emir'. The effect of Rph26 was to reduce the observed symptoms of leaf rust infection (uredinium number and infection type). In addition, this resistance also increased the fungal latency period and reduced the fungal biomass within infected leaves. The resulting introgression line 200A12, containing Rph26, was backcrossed to its barley parental cultivar 'Emir' to create an F population focused on detecting interspecific recombination within the introgressed segment. A total of 1368 individuals from this F population were genotyped with flanking markers at either end of the 1HL introgression, resulting in the identification of 19 genotypes, which had undergone interspecific recombination within the original introgression. F seeds that were homozygous for the introgressions of reduced size were selected from each F recombinant and were used for subsequent genotyping and phenotyping. Rph26 was genetically mapped to the proximal end of the introgressed segment located at the distal end of chromosome 1HL. Molecular markers closely linked to Rph26 were identified and will enable this disease resistance gene to be combined with other sources of quantitative resistance to maximize the effectiveness and durability of leaf rust resistance in barley breeding. Heterozygous genotypes containing a single copy of Rph26 had an intermediate phenotype when compared with the homozygous resistant and susceptible genotypes, indicating an incompletely dominant inheritance.

Development of barley introgression lines carrying the leaf rust resistance genes Rph1 to Rph15

“…Breeding cultivars with resistance is the preferred method of controlling barley leaf rust because fungicide applications, while effective, are rarely economical and can contaminate the environment. To date, 27 major effect resistance genes, referred to as reaction to Puccinia hordei (Rph) genes, have been identified and mapped across the barley genome (Kavanagh, Singh, Bansal, & Park, 2017;König et al, 2012;Park et al, 2015;Yu et al, 2018;Ziems et al, 2017). Although many of these resistance genes have been rendered ineffective in deployed cultivars due to the appearance of new virulent pathotypes of P. hordei, they still provide a means to characterize virulence phenotypes in the pathogen.…”

High-resolution mapping ofRym14Hb, a wild relative resistance gene to barley yellow mosaic disease

“…resistance exhibited from a plant species against all isolates of a pathogen which is not coevolutionary adapted, are particularly promising as they are thought to cover a larger resistance spectrum and to be more durable (Ayliffe and Sørensen 2019). Bulbous barley (Hordeum bulbosum L.), a wild relative and representative of the secondary gene pool of cultivated barley (Hordeum vulgare L.), has been described as source of resistance to numerous barley pathogens, including barley leaf rust (Johnston et al 2013;Yu et al 2018) and barley powdery mildew (Xu and Kasha 1992;Pickering et al 1995;Shtaya et al 2007). So far, all H. bulbosum accessions investigated exhibited resistance to BaMMV and BaYMV (Ruge et al 2003), suggesting that the species is probably a non-host to those viruses.…”

Resistance of barley cultivars approved for use in Russia to harmful organisms and toxic aluminum ions

“…В настоящее время 75% выращиваемых в Европе сор-тов защищены этими генами (Dreiseitl, 2017). Устойчивость к возбудителю карликовой ржавчины контролируется 26 генами Rph (Park et al, 2015;Kavanagh et al, 2017;Yu et al, 2018), причем, как и в случае с B. graminis, большинство аллелей неэффективны против P. hordei.…”