Thesis (Ph.D.)--Murdoch University, 2008. / Thesis submitted to the Faculty of Health Sciences. Includes bibliographical references (leaves 243-296)

Thesis (Ph.D.)--Murdoch University, 2006. / Thesis submitted to the Division of Science and Engineering. Includes bibliographical references (leaves 330-343).

Thesis (Ph.D)--Murdoch University, 2007. / Thesis submitted to the Divsion of Health Sciences. Includes bibliographical references (leaves 215-250).

T. aestivum ssp. spelta Iranian type has long been thought to potentially be the direct non-free threshing hexaploid progenitor. I evaluated a RIL population derived from a cross between CS and Iranian spelta accession P503 to identify loci suppressing free-threshabilty in P503. Identification of QTL associated with threshability in region known to harbor the Tg2A gene, and an inactive tg2D allele supported the hypothesis of Iranian spelta being derived from a more recent hybridization between free-threshing hexaploid and emmer wheat. Parastagonospora nodorum is an important fungal pathogen and secretes necrotrophic effectors that evoke cell death. In this research, a DH population segregating for Snn5 was used to saturate Snn5 region of chromosome 4B with molecular markers. The physical distance between Snn5 flanking markers was narrowed to 1.38 Mb with genetic distance of 2.8 cM. The markers developed in this study will provide a strong foundation for map-based cloning of Snn5.