A segment of Triticum militinae chromosome 7G harbors a gene(s) conferring powdery mildew resistance which is effective at both the seedling and the adult plant stages when transferred into bread wheat (T. aestivum). The introgressed segment replaces a piece of wheat chromosome arm 4AL. An analysis of segregating materials generated to positionally clone the gene highlighted that in a plant heterozygous for the introgression segment, only limited recombination occurs between the introgressed region and bread wheat 4A. Nevertheless, 75 genetic markers were successfully placed within the region, thereby confining the gene to a 0.012 cM window along the 4AL arm. In a background lacking the Ph1 locus, the localized rate of recombination was raised 33-fold, enabling the reduction in the length of the region containing the resistance gene to a 480 kbp stretch harboring 12 predicted genes. The substituted segment in the reference sequence of bread wheat cv. Chinese Spring is longer (640 kbp) and harbors 16 genes. A comparison of the segments' sequences revealed a high degree of divergence with respect to both their gene content and nucleotide sequence. Of the 12 T. militinae genes, only four have a homolog in cv. Chinese Spring. Possible candidate genes for the resistance have been identified based on function predicted from their sequence.

Department of Chemistry and Biotechnology Tallinn University of Technology Akadeemia tee 15 19086 Tallinn Estonia

Institute of Experimental Botany of the Czech Academy of Sciences Centre of the Region Haná for Biotechnological and Agricultural Research Šlechtitelů 31 78371 Olomouc Czech Republic

Institute of Experimental Botany of the Czech Academy of Sciences Centre of the Region Haná for Biotechnological and Agricultural Research Šlechtitelů 31 78371 Olomouc Czech Republic Biological and Environmental Science and Engineering Division King Abdullah University of Science and Technology Thuwal 23955 6900 Kingdom of Saudi Arabia

Institute of Experimental Botany of the Czech Academy of Sciences Centre of the Region Haná for Biotechnological and Agricultural Research Šlechtitelů 31 78371 Olomouc Czech Republic Limagrain Central Europe Cereals s r o Hrubčice 111 79821 Bedihošť Czech Republic

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