Quality traits. Pre-harvest sprouting tolerance (PHS)

Contributed by Mark Sorrells (mes12@cornell.edu)

RFLP markers

The major QTL for PHS tolerance (Sorrells, unpublished) is located close to the microsatellite locus Xbarc055 and explains about 32% of the variation. Flanking markers, gwm319 and gwm429 are each 8 cM away. Originally, the RFLP locus Xbcd1434 had a larger effect (Anderson et al. 1992) along with C24 on chromosome 1S however, in the Cayuga x Caledonia population, the Xbarc055 QTL has dwarfed the effect of other loci. This region was originally reported as linked to Xcdo64 but that marker is several centimorgans away. The RFLP probe, C24, developed from a barley BAC library, maps 2-3 cM away from the Xbcd1434 locus and can be used together with bcd1434 for selection of the second locus; however, this locus only explains about 5% of the variation now (Mark Sorrells, personal communication). A third QTL close to the Xgwm071 microsatellite locus located on 2AS explaining about 7% of the variation was also highly significant over 3 years. For laboratory methods dealing with the detection of RFLP markers you can visit Mark Sorrells' protocols web page or J. Dubcovsky's PLB161 laboratory class notes.

PCR markers

Three PCR-based markers are linked to the major QTL: Xbarc055, flanked by Xgwm319, and Xgwm429. A second QTL is close to the RFLP loci Xbcd1434 and C24 near the end of chromosome 1BS; however, no reliable microsatellite markers are polymorphic for this region in either the NY18 x CC population or Cayuga x Caledonia. The Xgwm071 marker on 2AS was highly significant but flanking markers are not yet identified.

Xbarc055. PCR products for Cayuga, Caledonia, Richland and several BC1 S1 lines.