An Adult Plant Stripe Rust Resistance Gene Maps on Chromosome 7A of Australian Wheat Cultivar Axe

Abstract

Australian wheat cultivar Axe produced resistant to moderately resistant stripe rust responses under field conditions and was exhibiting seedling response varying from 33C to 3+ under greenhouse conditions. Experiments covering tests at different growth stages (2nd, 3rd and 4th leaf stages) demonstrated the clear expression of resistance at the 4th leaf stage under controlled-environment greenhouse conditions. A recombinant inbred line (RIL) population was developed from the Axe/Nyabing-3 (Nyb) cross. Genetic analysis of Axe/Nyb RIL population in the greenhouse at the 4th leaf stage showed monogenic inheritance of stripe rust resistance. Selective genotyping using the iSelect 90K Infinium SNP genotyping array was performed and the resistance locus was mapped to long arm of chromosome 7A and named Yr75. The Axe/Nyb RIL population was genotyped using a targeted genotype-by-sequencing (tGBS) assay and the resistance-linked SNPs were converted into kompetitive allele specific PCR (KASP) markers. These markers were tested on the entire Axe/Nyb RIL population and markers sunKASP_430 and sunKASP_427 showed close association with Yr75 in Axe/Nyabing-3 RIL population. A high-resolution mapping family of 1032 F2 plants from the Axe/Nyb cross was developed and genotyped with sunKASP_430 and sunKASP_427 and these markers flanked Yr75 at 0.3 cM and 0.4 cM, respectively. These markers covers 1.24Mb of the physical map of Chinese Spring and can be used for future map-based cloning of this gene.

Mapping and validation of a novel major QTL for resistance to stripe rust in four wheat populations derived from landrace Qishanmai

“…Certain APR genes/ QTL, such as Yr18, Yr29 and Yr46 (Rosewarne et al, 2013) and QYrst.wgp-6BS.1/Yr78 (Santra et al, 2008;Dong et al, 2017), have been demonstrated to confer durable resistance sensu Johnson (1984) and Line (2002). There are also reports where APR was detectable as early as at the 4th leaf stage (Ma and Singh, 1996;Quan et al, 2013;Segovia et al, 2014;Chhetri et al, 2016;Kanwal et al, 2021), being described as "mid-stage resistance" (Kanwal et al, 2021) and "juvenile stage" resistance (Segovia et al, 2014).…”