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Rust diseases caused by Puccinia spp. are specialised to different economically important crops such as wheat and barley and can cause significant crop failure when severe. For many decades, genetic resistance has proven effective in protecting crops against rust pathogens. However, the ability of rust pathogens to evolve rapidly can lead to the emergence of new virulent races that can overcome genetic resistance. Therefore, the identification of new durable sources of resistance is essential for crop production and food security. Barley is a diploid crop with a reference genome sequence that is a near non-host to some non-adapted rust pathogens. Thus, the barley-Puccinia pathosystem is amenable for studies of the genetic architecture of resistance to rust pathogens. This thesis aims to determine the genetic basis of specificity of resistance in different barley-Puccinia pathosystems and to identify valuable sources of resistance in barley that can be used for genetic improvement of cereal crops. Chapter one contains a detailed review of the literature, addressing aspects of biology of barley and rust pathogens as well as mechanisms of host and non-host resistance. Chapter two investigates the genetic architecture of non-host resistance in barley using diverse Puccinia isolates and identifies non-host resistance (NHR) QTL that are suitable for either map-based or rapid cloning approaches. Chapter three examines the isolate specificity and polygenic inheritance of resistance in barley to different P. striiformis isolates. Chapter four generates a high-density linkage map using DArT-Seq markers with the aim of mapping loci for seedling and adult plant resistance to adapted stripe, leaf and stem rust pathogens. Chapter five delivers an overall conclusion based on the findings of the thesis and includes future paths and perspectives. |
