Introgression of the coupled Sr2/Fhb1 for resistance to stem rust and Fusarium head blight into Uruguayan elite wheat cultivars
Stem rust (SR) and Fusarium head blight (FHB) threaten the sustainability of wheat production worldwide. Sr2 is a widely used gene conferring partial, but durable, resistance to SR. Fhb1 confers a significant level of FHB resistance, but is poorly represented in the INIA-Uruguay wheat-breeding program. Sr2 and Fhb1 are linked in repulsion (~3 cM apart) on chromosome 3B. However, lines with Sr2 and Fhb1 in coupling were recently developed at the University of Minnesota, USA (kindly provided by J. Anderson). In order to incorporate Sr2/Fhb1 into Uruguayan elite wheat cultivars the donor line was crossed and backcrossed with four cultivars lacking both genes and expressing an intermediate to low level of resistance to SR and FHB: G?nesis 2375, G?nesis 6.87, INIA Madrugador, and INIA Don Alberto. Genotypes carrying Sr2/Fhb1 were selected using molecular marker UMN10; 250 BC2F1 were obtained for each recurrent parent. BC3F1 plants positive for UMN10 will be selected. The effect of Sr2/Fhb1 on response to SR and FHB in the different genetic backgrounds will be quantified by comparing disease severities of BC3F2 homozygotes with and without the UMN10 marker. Hopefully the introduction of Sr2/Fhb1 will contribute in reducing the risk of SR and FHB in wheat crops in Uruguay.