Submitted to: Plant and Animal Genome VX Conference Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 10/3/2004
Publication Date: 1/10/2005
Citation: Lu, H., Fellers, J.P., Friesen, T.L., Meinhardt, S.W., Haen, K.M., Faris, J.D. 2005. Towards positional cloning of the Tsn1 gene in wheat. Plant and Animal Genome Abstracts. p. 359.
Technical Abstract: Tsn1 conditions sensitivity to a host-selective proteinaceous toxin (Ptr ToxA) produced by the pathogenic fungus Pyrenophora tritici-repentis (Died.) Drechs. A large F2 population consisting of 5378 gametes was produced to develop a high-resolution map for positional cloning of the gene. Chromosome walking in conjunction with complete sequencing of BACs identified in the 'Langdon' durum BAC library was initiated from two AFLP-derived markers Xfcg17 and Xfcg9 that flank the Tsn1 gene at 0.24 and 0.46 cM, respectively. So far, three BACs on the Xfcg17 side of the gene have been sequenced. The new markers that were developed from these BACs spanning 215 kb cosegregated in the F2 population, suggesting that recombination is greatly suppressed in the vicinity of Xfcg17. On the Xfcg9 side of the gene, a contig of more than 500 kb has been constructed, and the genetic distance between Tsn1 and the closest marker has been narrowed down to 0.09 cM. Physical to genetic distance ratios in the Tsn1 region range from 464 kb/cM to 12 Mb/cM. From the regions that have been sequenced, we have identified about 20 genes, many of which are genes that encode cell wall-associated receptors or kinases. The cloning and characterization of Tsn1 will increase our knowledge of the host-pathogen interaction.