Mapping suitable niche for cactus and legumes in diversified farming in drylands
Targeted Mapping of Loci Conferring Resistance to Yellow Rust in Pavon-76/ Borlaug RIL Population
1. ICARDA Targeted Mapping of Loci Conferring Resistance to Yellow Rust in Pavon-76/ Borlaug RIL Population AbdulqaderJighly; YaljaroukaA; Nazari K; Tahir I; AbdallaO; OgbonnayaFC IWSR Symposium ICARDA
2. Outlines Introduction Serve epidemic 2009-10 YR genes summary YR genes – 2010 Aim of the study Study Plan Plant Material Progress so far Summary
3. Introduction Stripe rust, caused by Pucciniastriiformis, is one of the most globally important fungal diseases of wheat that cause significant annual yield losses. In 2009-10, the breakdown of Yr27 has caused significant yield losses in Syria, Turkey, Iran, Uzbekistan, Morocco, Ethiopia, and Kenya, threatening the food security and livelihood of resource poor farmers (Hodson and Nazari 2010). http://www.globalrust.org/traction?type=single&proj=Pathogen&sort=2&stickyparams=sort&rec=206
8. Previous Work The Pavon-76 variety (spring wheat) has been mapped before by (Williams et al. 2006) in the cross Pavon-76/Avocet with AFLP and SSR markers. Based on the previous study, three locations (1BL, 3BS and 6BS) showed significant link to stripe rust resistance in Pavon-76 with some AFLP markers and only 1 SSR marker on 1BL. The source of resistance (Pavon-76) showed a very good resistance level for the new stripe rust race.
9. Aim of the Study Developing molecular markers which are more closely linked to those genomic locations and more useful for breeding programs and marker assisted selection than AFLP markers. Discovering more genomic locations that linked to stripe rust resistance in this important gene pool.
10. The Study Plan Field Scoring for twoyears in Tel-hadya. Bulk segregant analysis using molecular markers with known link to different YR genes Applying different kinds of molecular markers to construct a high resolution linkage map which are: SSR CAPs SNPs (based on NSF wheat SNP project) RGA EST-SSR
11. The Study Plan The following link contains 5425 designed EST-SSR primers for wheat. We search for RGA motifs with more than 70% identity in this file. The ESTs that contain high density of RGA motifs have been chosen to be requested. http://wheat.pw.usda.gov/ITMI/EST-SSR/LaRota/table3_est-ssr%20designed%20primers.xls CA707339
12. Plant materials Stripe rust resistance has been studied on 301 recombinant inbred lines (F7) of the cross Pavon-76/Borloug in 2009-10. The source of resistance (Pavon-76) showed a very good resistance level
17. Bulk description The DNA of at least five lines that showed similar resistant classification were used for bulk segregant analysis as follows: 10 MR 15 MR 20 MR 20 M * S 76 SSR (simple sequence repeat) and RGA (resistance gene analogue) markers should be applied on those bulked lines, 30 of them have been applied and the others have been requested.
18. Bulk Results Two markers on chromosome 1BL were polymorphic between the bulks . Each marker seems to be linked to a different gene because the first one –Xwmc631– showed coupling phase with the source of resistance (Pavon-76) and the other one –Xbarc181– showed a repulsion phase with the same parent. The 1BL linkage group indicate that.
19. Up to Date Borl Pavon-76 * S 20 MR 20 M 15 MR 10 MR Borl Pavon-76 * S 20 MR 20 M 15 MR 10 MR
20. Up to Date We also get a single markers on chromosome 6BS –Xwmc487– which linked to stripe rust resistance but we weren’t able to construct a linkage group because of the lack of polymorphic markers. The R2 value for this region was about 5%, this may increase if we add more markers.
21. Up to Date 380 SSR markers has been screened on the parental lines: 92 markers of the whole set showed polymorphic alleles. 15 markers of those 92 polymorphic ones have been applied on the whole population. 7 markers of those 15 have been mapped on two locations 1BL and 2BS
22. Summary Pavon-76 showed a good level of resistance to the new race of stripe rust. Pavon-76/Borloug RIL population has been planted again in 2010-11. Two QTLs on chromosome 1BL and one on 6BS has been detected so far based on some SSR markers. Different molecular markers (EST-SSR, RGA, STS) are being applied on the population to identify markers for MAS.