Characterization of Stem Rust Resistant
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8th Internation Wheat Conference E.Alwan poster


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Characterization of Stem Rust Resistant Genes in Wild Tetraploids

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8th Internation Wheat Conference E.Alwan poster

  1. 1. C Characterization of Stem Rust Resistant t Genes in Wild Tetraploids Alwan E1,2, Ogbonnaya FC2*, Ayele B3, Nazari K2, Abdalla O2, Yahyaoui A4, and Hakim SH1 CGIAR 1 Aleppo University, Faculty of Agriculture, Aleppo, Syria. 2 ICARDA, PO Box 5466, Aleppo, Syria 3 Ethiopian Institute of Agricultural Research, Box 2003, Addis Ababa, Ethiopia. ICARDA-CIMMYT Wheat Improvement Program, PO Box 5466, Aleppo, Syria 4 *Corresponding author: F.Ogbonnaya@cgiar.org Abstract 200 A total of 73 wild tetraploid wheat accessions showing adult plant resistance (APR) were analyzed using molecular markers linked reportedly to wheat stem rust race Ug99 resistance genes. The wheat accessions were identified based on seedling and 150 adult plant test under heavy Ug99 inoculation conducted at Debre Zeit, Ethiopia. The accessions were haplotyped for stem rust resistance genes Sr2, Sr22, Sr26, Sr36, Sr40 using linked microsatellite (SSR) and diagnostic sequence tagged sites (STS). Of the accessions tested, 2 accessions showed the diagnostic fragment associated Sr2 Sr2 120 bp with Sr2-linked SSR markers; while 1, 7, and eight accessions possessed the DNA Control Marker fragment associated with Sr22, Sr36, and Sr40 resistance genes respectively . About 75% of the wild tetraploid accessions do not possess either SSR or STS haplotypes associated with the currently mapped Ug99 effective genes that we investigated. Our Figure 1. PCR amplification of wild tetraploids with Sr2 linked marker. preliminary results indicate that wild tetraploid accessions could provide potentially new sources of durable stem rust resistance in wheat. Introduction 250 Sr22 235 Stem rust (caused by Puccinia graminis f. sp. tritici Eriks. & E. Henn) is one of the 200 deadliest fungal diseases of wheat, which until the mid 1950s posed a tremendous threat Diffrential to wheat production worldwide. The disease was brought under control through the Control 150 bp deployment of genetic resistance using mostly major genes transferred from cultivated Marker rye and wild relatives of wheat until recently. However, the threat was renewed by the Figure 2. PCR amplification of wild tetraploids with Sr22 linked marker. emergence of a new race commonly known as Ug99 designated “TTKS” (Singh et al. 2006), virulent on most of the widely used genes, with reported yield losses in Kenya and Ethiopia ranging from to 20-50%. One accession of T. turgidium subsp dicoccoides with the phenotype SS/AMR also Use of molecular markers would enhance the effective deployment of resistance genes. possessed the DNA fragment linked to Sr22 (Fig. 2). Currently, about 50 stem rust resistance Sr genes have been identified and mapped to specific chromosome (McIntosh et al. 2008). Amongst the mapped Sr genes, molecular Additionally, six accessions of T.timopheevii var. timopheevii, and one of T. turgidium markers have been identified linked to some Ug99 effective resistance genes. The subsp dicoccoides which displayed seedling susceptibility and adult plant resistance objective of this study was to determine the frequency of the DNA markers linked with (SS/AR) possessed the SSR haplotype linked to Sr36. Further, three accessions of T. TTKS effective resistance genes, Sr2, Sr22, Sr26, Sr36, and Sr40 in wild tetraploids, turgidium subsp dicoccon, two of T. turgidium subsp dicoccoides, two of T.timopheevii in order to identify those carrying genes likely different from those previously reported. var. timopheevii and one accession of T. turgidium subsp turanicum possessed the SSR fragment linked to Sr40 gene. However, none of the tested accessions showed the presence of the DNA fragment linked to Sr26. Materials and Methods In total, about 75% of the wild tetraploid accessions do not possess either SSR or The wild tetraploid wheat accessions used in this study consisted of the following STS haplotypes associated with the currently mapped Ug99 effective genes that we accessions: investigated. The results indicate that wild tetraploids of wheat could provide potentially T. turgidum subsp. dicoccoides 28 T. turgidum subsp. carthlicum 6 new sources of durable stem rust resistance in wheat. These are further being genotyped T. turgidum subsp. dicoccon 18 T. turgidum subsp. turanicum 4 as more markers become available to ensure that only those with new APR genes are T. timopheevii subsp. timopheevii 10 T.timopheevii var araraticum 4 used in germplasm enhancement of durum and bread wheat. T. turgidum subsp. polonicum 1 T. turgidum subsp. turgidum 2 Eight linked and diagnostic SSR and STS markers were chosen for haplotyping five Table 2. Distribution of diagnostic markers linked to stem rust resistance major stem rust resistance genes located on A and genes Sr2, Sr22, Sr26 and Sr36 in wild Triticum species B genomes (Table 1). PCR reaction was carried out as previously reported by the authors. A group Gene of monogenic lines having the above-mentioned Species sr2 sr22 sr26 sr36 sr40 No. of lines major genes in addition to some lines previously T. turgidium subsp dicoccon 3 3 characterized and known to possess Sr genes were T. turgidium subsp dicoccoides 2 1 1 1 5 used as checks in this study. T. turgidium subsp turgidium 1 1 Results and Discussion T. turgidium subsp turanicum 1 1 Table 2 summarizes the results of charactering wild T.timopheevii var timopheevii 6 2 8 Triticum species with Sr linked and/or diagnostic Total 18 markers. Among 73 accessions, two accessions (T. turgidium subsp dicoccoides and T. turgidium subsp turgidium) which displayed seedling susceptibility and adult plant moderate resistance (SS/AMR) showed the Sr2 haplotype (Fig. 1). References Mago R, Bariana HS, Dundas IS, Spielmeyer W, Lawrence GJ, Pryor AJ, Ellis JG (2005) Development of PCR markers for the selection of wheat stem rust resistance genes Sr24 and Sr26 in diverse wheat Table 1. Sr stem rust SSR –STS markers liked to Ug99 effective genes germplasm. Theor Appl Genet 111:496-504 located on AB genome. McIntosh, RA, Yamazaki Y, Dubcovsky J, Rogers WJ, Morris CF, Somers D, Appels R and Devos KM. (2008) Catalogue of gene symbols for wheat. Gene symbols., In R. A.McIntosh, (ed.), http://wheat.pw.usda. Fragment gov/GG2/Triticum/wgc/2008/GeneSymbol.pdf . Gene Origin Locus Chromosome References size (bp) Miranda LM, Perugini L, Srni´c G, Brown-Guedira G, Marshall D, Leath S, and Murphy JP (2007) Genetic Mapping of a Triticum monococcum derived Powdery Mildew Resistance Gene in Common Wheat. Crop Sr2 T. turgidum Xgwm533 120 3BS Sci 47:2323-2329. Xbarc133 117 Spielmeyer et al. 2003 Singh RP, Hodson DP, Jin Y, Huerta-Espino J, Kinyua MG, Wanyera R (2006) Current status, likely migration and strategies to mitigate the threat to wheat production. T. monococcum ssp. Spielmeyer W, Sharp PJ, Lagudah ES (2003) Identification and Validation of Markers Linked to 18 Broad- Sr22 Xcfa2019 235 7AL Miranda et al., 2007 boeoticum Spectrum Stem Rust Resistance Gene Sr2 in Wheat (Triticum aestivum L.). Crop Sci 43:333-336. Xcfa2123 245 Tsilo TJ, Jin Y, Anderson JA (2008) Diagnostic Microsatellite Markers for 1 the Detection of Stem Rust Resistance Gene Sr36 in Diverse Genetic Backgrounds of Wheat. Crop Sci 48:253-261. Sr26 Lophopyrum elongatum Sr26#43 207 6AL Mago et al., 2005 Yu L-X, Z. Abate Z, Anderson JA, Bansal UK, Bariana HS, Bhavani S, Dubcovsky J, Lagudah ES, Liu S, Sambasivam PK, Singh RP, Sorrells ME (2009) Developing and Optimizing Markers for Stem Rust Poster Design Abdurrahman Hawa Sr36 T. timopheevi Xwmc477 187 2BS Tsilo et al., 2008 Resistance in Wheat. Proceedings of Borlaug Global Rust Initiative. C.D. Obregon, Mexico, 2009: P39-56 Xstm733-2 153 Acknowledgments T. timopheevii ssp. Sr40 Xgwm344 2BS Yu et al., 2009 Staff of ICARDA’s biotechnology and genetic resources units, Ethiopian Institute for Agricultural Research, armeniacum Durable Rust Resistance in Wheat Project, Cornell University.