STS-PCR MARKERS APPROPRIATE FOR WHEAT-BARLEY INTROGRESSION

Introgression of chromosomal segments across large taxonomic distances has long been an objective of scientists interested in understanding the relationships between genes and their effect on phenotype. Barley and wheat represent cultivated members of the Triticeae with different zones of adaptation, different responses to pathogens, and different end-use characteristics. Introduction of small, well-characterized chr omosomal segments among grass relatives presents an opportunity to bot h better understand how genes perform in novel genomic environments an d to learn more about the evolutionary novelties which differentiate r elated species. Since the distribution of the wheat-barley addition li nes, the potential power and value of a comprehensive series of wheat/ barley translocation lines has been widely appreciated. A scarcity of easy-to-use markers which unambiguously distinguish barley loci from t heir wheat homologues has limited the ability of scientists to identif y the relatively rare inter-chromosomal recombination events which are the necessary antecedents of these lines. Since the single most criti cal pathogen affecting U.S. wheat producers is Karnal bunt (Tilletia i ndica) and since barley carries a gene conferring immunity, molecular markers may prove practically and immediately important. In this repor t we describe a series of 135 barley-specific markers amplified by 115 primer sets developed from sequences from previously mapped restricti on fragment length polymorphism (RFLP) markers. These easily distingui sh the cognate barley products from their wheat counterparts and shoul d find ready use in the identification of lines which contain wheat/ba rley translocation events.