Molecular mapping ofYrTZ2, a stripe rust resistance gene in wild emmer accession TZ-2 and its comparative analyses withAegilops tauschii

Wheat stripe rust, caused byPuccinia striiformisf. sp.tritici(Pst), is a devastating disease that can cause severe yield losses. Identification and utilization of stripe rust resistance genes are essential for effective breeding against the disease. Wild emmer accession TZ-2, originally collected from Mount Hermon, Israel, confers near-immunity resistance against several prevailingPstraces in China. A set of 200 F6:7recombinant inbred lines (RILs) derived from a cross between susceptible durum wheat cultivar Langdon and TZ-2 was used for stripe rust evaluation. Genetic analysis indicated that the stripe rust resistance of TZ-2 toPstrace CYR34 was controlled by a single dominant gene, temporarily designatedYrTZ2. Through bulked segregant analysis (BSA) and SSR mapping,YrTZ2was located on chromosome arm 1BS and flanked by SSR markersXwmc230andXgwm413with genetic distance of 0.8 cM (distal) and 0.3 cM (proximal), respectively. By applying wheat 90K iSelect SNP genotyping assay, 11 polymorphic loci (consist of 250 SNP markers) closely linked withYrTZ2were identified.YrTZ2was further delimited into a 0.8 cM genetic interval between SNP markerIWB19368and SSR markerXgwm413, and co-segregated with SNP markerIWB28744(attached with 28 SNP markers). Comparative genomics analyses revealed high level of collinearity between theYrTZ2genomic region and the orthologous region ofAegilops tauschii1DS. The genomic region between lociIWB19368andIWB31649harboringYrTZ2is orthologous to a 24.5 Mb genomic region between AT1D0112 and AT1D0150, spanning 15 contigs on chromosome 1DS. The genetic and comparative maps ofYrTZ2provide framework for map-based cloning and marker-assisted selection (MAS) ofYrTZ2.