Location: Cereal Crops ResearchTitle: Physical mapping of DNA markers linked to stem rust resistance gene Sr47 in durum wheat Author
|Saini, Jyoti - North Dakota State University|
|Long, Yunming - North Dakota State University|
|Rouse, Matthew - Matt|
Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/7/2017
Publication Date: 3/12/2017
Publication URL: http://handle.nal.usda.gov/10113/5700692
Citation: Klindworth, D.L., Saini, J., Long, Y., Rouse, M.N., Faris, J.D., Jin, Y., Xu, S.S. 2017. Physical mapping of DNA markers linked to stem rust resistance gene Sr47 in durum wheat. Theoretical and Applied Genetics. 130:1135-1154. doi: 10.1007/s00122-017-2875-7.
Interpretive Summary: In durum wheat, the race TTKSK (Ug99) of the stem rust pathogen can be controlled by the gene Sr47. The Sr47 gene is known to be located on a segment of DNA derived from chromosome 2S of goatgrass and incorporated into chromosome 2B of durum wheat. The chromosomal regions around Sr47 can be divided into four areas called bins. Molecular markers located in these bins can allow for easy selection of plants carrying the Sr47 gene, especially if the marker is in the same bin as Sr47 (bin 3). Therefore, our objective was to try to find markers that exhibit co-dominant inheritance and located in bin 3, and to produce a physical map of the location of those markers. We tested known markers on three populations in which the goatgrass segment carrying Sr47 was incorporated into a genetic background of the durum cultivar Joppa. No markers were found to map to bin1, but there were 7, 9, and 12 markers that mapped to bins 2, 3, and 4, respectively. We found four markers, Xrwgs38a, Xmag1729, Xwmc41 and TNAC3119, with good potential for use in selecting plants carrying gene Sr47. Except for Xwmc41, the markers show co-dominant inheritance. Only markers Xwmc41 and TNAC3119 mapped to bin 3. Although none of the four markers was useful in all situations, together the four should allow for selection of plants carrying Sr47 in any situation. The physical map produced in this study should be useful to geneticists in map based cloning of the Sr47 gene.
Technical Abstract: In durum wheat (Triticum turgidum subsp. durum), the gene Sr47 derived from Aegilops speltoides conditions resistance to race TTKSK (Ug99) of stem rust pathogen (Puccinia graminis f. sp. tritici). Sr47 is carried on small interstitial translocation chromosomes (Ti2BL-2SL-2BL·2BS) in which the Ae. speltoides chromosome 2S segments are divided into four bins in genetic stocks RWG35, RWG36, and RWG37. Our objective was to physically map molecular markers to bins and to determine if any of the molecular markers would be useful in marker assisted selection (MAS). Durum cultivar Joppa was used as the recurrent parent to produce three RWG BC2F2 populations. Each BC2F2 plant was genotyped with check markers to detect the segment carrying Sr47, and stem rust testing of BC2F3 progeny with TTKSK confirmed the genotyping. Forty-nine markers from published sources and 17 new SNP-derived SSR markers were evaluated on the BC2F2 populations for assignment of the markers to the bins. Sr47 was mapped to bin 3 along with 9 markers. No markers were assigned to bin 1; however, 7 and 12 markers were assigned to bins 2 and 4, respectively. Five markers generated heteroduplex amplicons exclusively in heterozygous plants. While marker Xrwgs38a did not detect the Ae. speltoides segment in RWG37, it remained the best codominant marker for MAS of RWG35 and RWG36 populations. Codominant marker Xmag1729 mapped to bin 4 and should replace Xgpw4043 for MAS of RWG37 populations. Markers Xwmc41 and TNAC3119 mapped to bin 3 and should be useful in breeding of all RWG populations.