Submitted to: Plant and Animal Genome VX Conference Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 10/25/2003
Publication Date: 1/10/2004
Citation: Haen, K.M., Lu, H., Friesen, T.L., Faris, J.D. 2004. Genomic targeting and high-resolution mapping of the Tsn1 gene in wheat. 12th Plant and Animal Genome Abstracts. p. 438.
Technical Abstract: Tan spot, caused by the fungal pathogen Pyrenophora tritici-repentis causes severe yield losses in wheat and durum. The Tsn1 gene acts dominantly to confer sensitivity to a host-selective proteinacious toxin (Ptr ToxA) produced by the fungus. Our objectives were to: 1) target markers to the Tsn1 genomic region, and 2) develop a high-resolution map of the Tsn1 locus. The techniques of methylation-sensitive AFLP, traditional AFLP, and cDNA-AFLP were combined with bulked segregant analysis (BSA) using various wheat and durum cytogenetic stocks to target markers to the Tsn1 genomic region. Over 500 primer combinations were screened resulting in the identification of 18 low-copy markers closely linked to Tsn1. High-resolution mapping of the markers delineated the Tsn1 gene to a 0.2 cM interval in a hexaploid wheat population consisting of 1,266 gametes, and to 0.8 cM in a durum wheat population consisting of 1,860 gametes. Comparisons with rice BAC/PAC sequences indicated the lack of synteny within the Tsn1 genomic region suggesting that rice genomics will not be useful for the isolation of Tsn1. However, the markers identified in this research will serve as a basis for the map-based cloning of Tsn1 directly from durum wheat. The isolation of Tsn1 will further our knowledge of wheat-tan spot interactions as well as host-pathogen interactions in general.