Mapping of a new stripe rust resistance locus Yr57 on chromosome 3BS of wheat

Abstract

A common wheat landrace, AUS27858, from the Watkins collection showed low seedling stripe rust response against Australian Puccinia striiformis f. sp. tritici pathotypes. Genetic analysis of stripe rust resistance indicated the involvement of two independent resistance loci YrAW1 and YrAW2. YrAW1 was mapped in chromosome 4AL and formally named Yr51. Ninety seeds of a heterozygous F3 line (HSB#5474; YrAW2yrAW2) were grown individually to produce a segregating population referred to as single gene segregating population #5474 (SGSP#5474) to map YrAW2. Monogenic segregation at the YrAW2 locus was confirmed among the SGSP#5474. YrAW2 was located in chromosome 3BS through DArT-based bulked segregant analysis. SGSP#5474 was advanced to F6 generation and was phenotyped for detailed mapping. Test of allelism with Yr4, previously located on chromosome 3BS, showed 5.2 ± 1.3 % recombination between YrAW2 and Yr4. Since there is no other stripe rust resistance gene located in the distal part of chromosome 3BS, YrAW2 was formally named Yr57. Markers gwm389 and BS00062676 flanked Yr57 at genetic distances of 2.0 and 2.3 cM, proximally and distally, respectively. These markers were genotyped on a set of Australian and Indian wheat cultivars and the absence of resistance-linked alleles of gwm389 and BS00062676 markers was shown in cultivars known to lack Yr57. These markers would be useful in marker-assisted pyramiding of Yr57 with other marker-tagged major and minor genes. The genetic stock carrying Yr57 singly has been deposited with the Australian Winter Cereal Collection, Tamworth, Australia, and it is accessioned as AUS91463.