A SIMPLE PCR-BASED METHOD FOR SCORING THE PH1B DELETION IN WHEAT

The amplified fragment length polymorphism (AFLP) technique was used t o isolate DNA sequences present in the euploid wheat Chinese Spring bu t not in the Chinese Spring ph1b mutant (which has a deletion of the P h1 gene, a suppressor of homoeologous chromosome pairing). The polymor phic DNA fragments identified by AFLP were then cloned, sequenced, and used to design two primer pairs. These primers were used in a PCR-bas ed assay to specifically amplify products from the Chinese Spring eupl oid but not from the ph1b mutant. This PCR assay can be carried out fr om extracted genomic DNA or directly from alkaline-treated wheat leave s, and the reaction products can be scored on a plus-minus basis, maki ng the screening amenable to automation. The reliability of the assay was tested using a F-1-derived doubled-haploid population of 55 lines which segregate for the ph1b deletion. This PCR-screening technique is less time and labour consuming, and more accurate and reliable, than cytologically based conventional methods.