Location: Crop Germplasm ResearchTitle: Molecular mapping of Cg1, a gene for resistance to anthracnose (Colletotrichum sublineolum) in sorghum) Author
|Gutierrez Rojas, L|
|Klein, Robert - Bob|
Submitted to: Euphytica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/10/2008
Publication Date: N/A
Citation: Interpretive Summary: Sorghum anthracnose, an important fungal disease which appears as spots or elongated lesions on the plant leaves, can cause yield losses of over 50% in grain sorghum, especially on susceptible cultivars. The most reliable method of controlling the disease is by planting resistant sorghum cultivars. However, screening for resistance is normally difficult due to the different races of the fungal pathogen and also the lack of disease pressure on the nurseries from year to year. With proper screening methods and using molecular tools, we were able to identify markers in the sorghum chromosome number 5. These markers were validated in the advanced crosses between BTx623 and SC748 breeding lines. The results of this study will be very useful in helping other sorghum scientists in screening and identifying large numbers of anthracnose-resistant sorghum lines within a short time.
Technical Abstract: Anthracnose, caused by the fungus Colletotrichum sublineolum 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. Here, we describe the search for molecular markers that co-segregate with Cg1, a dominant gene for resistance originally identified in cultivar. To identify molecular markers linked with the Cg1 locus, F2:3 plants derived from the BTx623 were analyzed with ninety-eight AFLP primer combinations. As a parent used in generating RFLP and AFLP maps and BAC libraries for sorthum, BTx623 was chosen as the susceptible parent. Four AFLP markers that co-segregate with disease resistance were identified, of which Xtxa6227 mapped within 1.8 cM of the anthracnose resistance locus. All four AFLP markers have been previously mapped to the end of sorghum linkage group LG-05. Sequence scanning of BAC clones spanning this chromosome led to the discovery that Xtxp549, a polymorphic simple sequence repeat (SSR) marker, mapped within 3.6 cM of the anthracnose resistance locus. To examine the efficacy of Xtra6227 and Xtxp549 for marker-assisted selection, thirteen breeding lines derived from crosses with sorghum line SC748-5 were genotyped. In twelve of the thirteen lines, the Xtra6227 and Xtxp549 polymorphism associated with Cg1 locus was still present, suggesting that Xtxa6227 and Xtxp549 could be useful for marker-assisted selection and for pyramiding Cg1 with other genes conferring resistance to C. sublineolum in sorghum.