Consensus Mapping and Identification of Markers for Marker-Assisted Selection of Wsm2 in Wheat

A recently identified Wheat streak mosaic virus (WSMV) resistance gene Wsm2 confers a high level of resistance. Objective of this study was to identify closely linked DNA markers for Wsm2 for use in marker-assisted selection (MAS) in wheat (Triticum aestivum L.). Two segregating populations (CO960293-2 x 'TAM 111' and CO960293-2 x 'Yuma') of F-2:3 families were evaluated for response to WSMV infection in growth chamber experiments. Forty-eight simple sequence repeat (SSR) or sequence-tagged site (STS) markers were screened for polymorphism between the parents of both populations. In the CO960293-2 x TAM 111 population, five markers were mapped to the region of Wsm2 with XSTS3B-55 being the closest marker (5.2 cM distal to Wsm2). In the CO960293-2 x Yuma population, eight markers were linked to Wsm2 with the closest marker Xbarc102 linked at 3.9 cM proximal to Wsm2. Results from consensus mapping of the two populations suggested that Xbarc102 was distal to Wsm2. The marker Xbarc102 was associated with Wsm2 in all 22 wheat lines derived from crosses between susceptible parents and either CO960293-2 or 'RonL' (also carrying Wsm2). The marker allele Xbarc102-219-bp present in CO960293-2 was amplified in polymerase chain reaction (PCR) from Wsm2-carrying genotypes CO960293-w133, RonL, and 'Snowmass' but not from the resistant line KS96HW10-3 (carrying Wsm1) or the susceptible genotypes 'Karl 92', 'TAM 107', and 'N96L9970'. Therefore, this marker should be useful for MAS of Wsm2 in breeding programs.