Mapping stem rust resistance loci effective in Kenya in Canadian spring wheat (Triticum aestivum L.) lines 'AAC Prevail' and 'BW961'

This study was conducted to identify and map stem rust resistance genes in Canada Western Red Spring (CWRS) wheat variety 'AAC Prevail' and elite line 'BW961MODIFIER LETTER PRIME. A population of 227 doubled haploid lines from 'AAC Prevail'/'BW961MODIFIER LETTER PRIME and parents were evaluated for their response to stem rust (Puccinia graminis) at Njoro, Kenya, from 2016-2019 and genotyped using a targeted genotyping by sequencing SeqSNP assay. 'AAC Prevail' and 'BW961MODIFIER LETTER PRIME were susceptible to race TTKSK in seedling tests in Canada. We identified stable QTL (significant in most environments tested) associated with field stem rust resistance on chromosome arms 2BS and 7AL, and minor QTL on 5AL, 6AS and 7BL. The QTL on 5AL, 7AL and 7BL were contributed by 'AAC Prevail', while those on 2BS and 6AS were contributed by 'BW961MODIFIER LETTER PRIME. The QTL on 7AL was detected across all environments and explained 9.5% to 39% of the variation in disease severity (DS) and infection response (IR). The QTL on 2BS was associated with DS in all environments and in three of four environments for IR, and explained 4.8% to 12% of the variation in DS and IR. In two environments, the combination of 2BS and 7AL significantly enhanced field stem rust resistance compared with either QTL singly. Using SNP markers closely linked to the novel QTL on 2BS and 7AL, Kompetitive Allele Specific PCR markers were developed and validated in the population. These results provide breeders with new information and markers to utilize these sources of stem rust resistance.

Automated summary

This study identified stable major and minor QTL associated with field stem rust resistance in 'AAC Prevail' and 'BW961MODIFIER LETTER PRIME', providing breeders with new information and markers to utilize these sources of stem rust resistance.