The major outcomes of this study include: Understanding the genetic architecture of triple rust resistance in accession CPI110672 Cloning and validation of Sr46b and Yr672 rust resistance candidate genes Fine mapping a leaf rust resistance (Lr39) gene Development of breeder-friendly molecular markers for Sr46, Yr672 and Lr39 Marker assisted introgression of Sr46b and Yr672 into a commercial cultivar Marker assisted pyramiding of Sr33/Sr45/Sr46b resistance genes using speed breeding technology v Declaration by author This thesis is composed of my original work, and contains no material previously published or written by another person except where due reference has been made in the text. I have clearly stated the contribution by others to jointly-authored works that I have included in my thesis. I have clearly stated the contribution of others to my thesis as a whole, including statistical assistance, survey design, data analysis, significant technical procedures, professional editorial advice, financial support and any other original research work used or reported in my thesis. The content of my thesis is the result of work I have carried out since the commencement of my higher degree by research candidature and does not include a substantial part of work that has been submitted to qualify for the award of any other degree or diploma in any university or other tertiary institution. I have clearly stated which parts of my thesis, if any, have been submitted to qualify for another award. I acknowledge that an electronic copy of my thesis must be lodged with the University Library and, subject to the policy and procedures of The University of Queensland, the thesis be made available for research and study in accordance with the Copyright Act 1968 unless a period of embargo has been approved by the Dean of the Graduate School.