Genetics of stripe rust resistance in a common wheat landrace Aus27492 and its transfer to modern wheat cultivars

Abstract

The development of resistant cultivars is a preferred way to manage the wheat rust pathogens. Successful breeding relies on the continuous discovery, characterization and deployment of genetically diverse resistance sources. This investigation covers the identification and characterization of the stripe rust (caused by Puccinia striiformis f. sp. tritici) resistance carried by a pre-Green Revolution wheat genotype, Aus27492, from France and its transfer to modern backgrounds. Genetic analysis of stripe rust resistance using an F 3 population derived from the cross of Aus27492 with the susceptible parent 'Avocet S' indicated digenic inheritance of all stage resistance. The underlying genes were tentatively named YrAW6 and YrAW7 and these loci were located in the long arms of chromosomes 2B and 5A, respectively, through the Illumina iSelect 90 K Infinium SNP genotyping array-based bulked segregant analysis (BSA). While YrAW7 was shown to be the same as the previously described stripe rust resistance gene Yr34 based on pathotypic specificity, YrAW6 appears to represent a new locus. To take these results from the laboratory to farmers' fields, derivatives of Aus27492 in the Australian wheat cultivars 'Emu Rock', 'Mace' and 'Suntop' were delivered to Australian wheat-breeding companies for use as donor sources.

Genome-wide association study and genomic prediction of resistance to stripe rust in current Central and Northern European winter wheat germplasm

“…Because resistance levels in this group can be highly affected by temperature, it also includes high-temperature adult-plant (HTAP) resistance genes (Chen 2013 ). Since strong selection pressure is exerted on the pathogen to become virulent against a single ASR gene and thus survive, the use of a combination or pyramiding of APR genes with effective ASR genes is recommended to achieve commercially acceptable levels of resistance (Bariana 2003 ; Gessese et al 2021 ).…”

“…The chromosomal positions of several stripe rust resistance genes and quantitative trait loci (QTL) were determined using classical mapping approaches (Tsomin et al 1990 ; Bariana and McIntosh 1993 ; Michelmore et al 1991 ; Xu et al 2008 ; Edae et al 2016 ; Gessese et al 2021 ) and, more recently, using genome-wide association studies (GWAS) (Bouvet et al 2021 ; Rollar et al 2021 ). To complement traditional QTL mapping, GWAS combined with high-density SNP genotyping have been successfully used as powerful tools for discovery of stripe rust resistance loci in a global collection of winter wheat accessions (Bulli et al 2016 ), spring wheat landraces (Kankwatsa et al 2017 ), diverse Indian spring wheat cultivars (Kumar et al 2020 ), US winter wheat cultivars and breeding lines (Mu et al 2020 ), elite wheats of the International Maize and Wheat Improvement Center (CIMMYT) (Juliana et al 2018), European winter wheat (Miedaner et al 2019 ), and modern Chinese wheat (Jia et al 2020 ).…”

“…Thus, continued efforts are needed to characterize new resistance sources for maintaining or increasing resistance levels. Compared to wild relatives of wheat, identification and characterization of resistance genes from landraces and cultivated genotypes is more preferable due to the absence of undesirable agronomic traits and chromosomal linkage drags in the latter (Burt et al 2014 ; Gessese et al 2021 ). The selection and combination of resistance genes already present in the advanced breeding pool allows for a faster development of new resistant varieties.…”

Registration of the PI 173438/WA 8137 wheat doubled haploid mapping population

“…tritici Erikss. ), such as Yr47 (Bansal et al., 2011), Yr51 (Randhawa et al., 2014), Yr57 (Randhawa et al., 2015), Yr80 (Nsabiyera et al., 2018), Yr82 (Pakeerathan et al., 2019), YrAW6 , and YrAW7 (Gessese et al., 2021), have been identified in landraces and are being incorporated into modern cultivars. The gene Yr10 is found in the Turkish landrace PI 178383 and has been incorporated into PNW cultivars (Chen et al., 1995).…”