|Klein, Robert - Bob|
Submitted to: Euphytica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/11/2008
Publication Date: 1/9/2009
Citation: Ramasamy, P., Menz, M.A., Metha, P.J., Katile, S., Gutierrez, R.L., Klein, R.R., Klein, P.E., Prom, L.K., Schlueter, J.A., Rooney, W.L., Magill, C.W. 2009. Molecular mapping of cgl, a gene for resistance to anthracnose (Collectotrichum sublineolum) in sorghum. Euphytica. 165:597-606. Interpretive Summary: Stable host plant resistance has been difficult even in regions where sorghum anthracnose occurs annually because of the different races of Colletotrichum sublineolum. Normally, selection for anthracnose resistance in sorghum has been hampered by difficulties in obtaining the proper disease pressure to permit accurate identification of resistant plants. The results reported here is the closest molecular markers viz., AFLP-Xtxa6227 at a distance of 1.8 cM and SSR- Xtxp549 at a distance of 3.6 cM to the Cg1 locus in LG-05. These two markers close eco-segregation were validated in the advanced BTx623 *SC748 breeding population for anthracnose resistance and hence, can be used in marker-assisted breeding.
Technical Abstract: Anthracnose, caused by the fungus Colletotrichum sublineolum (anamorph C. graminicola), is one of the most destructive diseases of sorghum and has been reported in most areas where the crop is grown. Several control strategies have been developed but host plant resistance has been regarded as the most effective strategy for disease control. To this end, a dominant gene (Cg1) for resistance to the pathogen has been identified by conventional genetic analysis in a cross between ‘SC748-5’ (resistant parent, Cg1Cg1) and ‘BTx623’ (susceptible parent, cg1cg1). To identify molecular markers linked with the Cg1 locus, F2:3s plants derived from the BTx623 by SC748-558 cross were analyzed with ninety eight AFLP primer combinations. Four AFLP markers cosegregating with disease resistance were identified, and all four AFLP markers have been previously mapped to the end of sorghum linkage group SBI-05. Sequence scanning of BAC clones spanning this chromosome 05 region revealed a polymorphic SSR (Xtxp549) that mapped within 3.6 cM of the anthracnose resistance locus. To examine the efficacy of Xtxp549 for marker-assisted selection, thirteen unique advanced breeding lines derived from crosses with sorghum line SC748-5 were genotyped. In twelve of the thirteen lines, Xtxp549 correctly tagged the Cg1 locus suggesting that Xtxp549 and AFLP Xtxa6227 could be useful for marker-assisted selection and for pyramiding of Cg1 with other genes conferring resistance to C. sublineolum in sorghum.