The development of PCR-based markers for the selection of eyespot resistance genes Pch1 and Pch2
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Two eyespot resistance genes (Pch1 and Pch2) have been characterised in wheat. The potent resistance gene Pch1, transferred from Aegilops ventricosa, is located on the distal end of the long arm of chromosome 7D (7DL). Pch2 derives from the variety Cappelle Desprez and is located at the distal end of chromosome 7AL. The RFLP marker Xpsr121 and the endopeptidase isozyme allele Ep-D1b, are very closely linked to Pch1, probably due to reduced recombination in the region of the introgressed A. ventricosa segment. Pch2 is less closely linked to these markers but is thought to be closer to Xpsr121 than to Ep-A1b. In the present study simple sequence repeat (SSR) markers were integrated into the genetic map of a single chromosome (7D) recombinant (RVPM) population segregating for Pch1. Sequence-tagged-site (STS)-based assays were developed for Xpsp121 and a 7DL wheat EST containing a SSR. SSR markers Xwmc14 and Xbarc97 and the Xpsr121-derived marker co-segregated with Pch1 in the RVPM population. A single chromosome (7A) recombinant population segregating for Pch2 was screened for eyespot resistance and mapped using SSRs. QTL interval mapping closely associated Pch2 with the SSR marker Xwmc525.
KeywordsSimple Sequence Repeat Marker Chinese Spring RFLP Marker Recombinant Population Eyespot Resistance
We wish to thank the John Innes Centre Genome Laboratory (JGL) for Pch2 SSR analysis. Thanks to Bill Hollins and members of his team who kindly co-ordinated the second disease trial. This work was jointly funded by BBSRC and Nickerson (UK) Ltd through a BBSRC-CASE award to N. H. Chapman, and BBSRC and the Home Grown Cereal Authority (HGCA) through a BBSRC-CASE award to C. Burt.
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