| | | Document Type | : | Latin Dissertation | | Language of Document | : | English | | Record Number | : | 53531 | | Doc. No | : | TL23485 | | Call number | : | 3328331 | | Main Entry | : | Pablo Daniel Olivera Firpo | | Title & Author | : | Genotypic and phenotypic diversity of Sharon goatgrass (Aegilops sharonensis) and genetics of resistance to wheat fungal diseasesPablo Daniel Olivera Firpo | | College | : | University of Minnesota | | Date | : | 2008 | | Degree | : | Ph.D. | | student score | : | 2008 | | Page No | : | 250 | | Abstract | : | Sharon goatgrass (Aegilops sharonensis), a wild relative of wheat, is a rich source of genetic diversity for wheat improvement. This species is endemic to the coastal plains of Israel and southern Lebanon, and is rapidly losing its natural habitats due to extensive agriculture and urban development. The objectives of this dissertation were to characterize Sharon goatgrass for genetic resistance to wheat fungal pathogens and to study the genetic diversity of the species. Our results indicate that Sharon goatgrass is a rich source of resistance to many wheat fungal pathogens. A higher frequency and level of resistance were observed to biotrophic pathogens (powdery mildew, leaf rust, stem rust, and stripe rust) in comparison to necrotrophic pathogens (tan spot, spot blotch, and Fusarium head blight). Four accessions exhibiting multiple resistance (1644, 2172, 2173, and 591) were identified as candidates for genetic studies and gene introgression programs. Resistance to leaf rust, stem rust, and powdery mildew in selected Sharon goatgrass accessions was conferred by genes with major effects. Accessions carrying multiple resistance genes to stem rust were observed. Different resistance genes to leaf rust and powdery mildew were identified in accessions collected from different locations in Israel. A medium-density linkage map (818 cM across 10 linkage groups) of Sharon goatgrass was constructed using 389 DArT and microsatellite markers. The single dominant genes conferring resistance to leaf rust race THBJ (LrAeSh1644) and stem rust race TTTT (SrAeSh1644 ) in accession 1644 were positioned in linkage group 1 (chromosome 6Ssh) and 2 (chromosome 1Ssh), respectively. LrAeSh1644 was mapped 1.9 cM from marker wpt-9881, whereas SrAeSh1644 was mapped 1.7 cM from marker wpt-9845. Finally, analysis of genetic diversity of 106 Sharon goatgrass accessions revealed a high level of diversity that was comparable to Aegilops species with larger geographic distribution. The genetic structure of Sharon goatgrass is characterized by high diversity within locations and by a short distance similarity between populations. The information generated from this study will be useful in gene introgression programs and will provide valuable data for developing conservation strategies and future germplasm collection surveys. | | Subject | : | Biological sciences; Aegilops sharonensis; Fungal diseases; Plant disease resistance; Sharon goatgrass; Wheat; Plant sciences; 0480:Plant sciences | | Added Entry | : | B. J. Steffenson | | Added Entry | : | University of Minnesota |
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