Thesis
Identification of sources of resistance to rhizoctonia root rot in mutant and wild barley
Washington State University
Master of Science (MS), Washington State University
2012
Handle:
https://hdl.handle.net/2376/102006
Abstract
Rhizoctonia root rot and bare-patch caused by Rhizoctonia solani AG-8 is an important disease that limits yields of cereal crops in no-till/direct seeding systems in the Pacific Northwest (PNW) region of the United States, and in turn limiting the widespread adoption of this system in this region. Due to the dearth of commercial cereal cultivars that are genetically resistant to the fungus, growers have mostly relied on the combination of various cultural practices to combat the disease. Unfortunately these practices do not eliminate the pathogen from the soil or significantly increase yield. Spring barley is highly susceptible to the disease. However, spring barley serves as an important rotational crop in the PNW offering growers with several rotation benefits such as disease reduction and increased productivity, especially when grown in rotation with wheat. With the objective of identifying sources of resistance to the disease in barley, two different experiments were conducted. In the first experiment, M2 populations of sodium azide barley mutants of cultivar Lenetah and breeding line 05WA-316.99 were screened for disease reaction to the fungus. Putative mutants were verified to confirm observed resistance. From these two lines, 10 putative M3 individuals were identified and crossed to wild-type progenitor for genetic analysis. Evaluating the BC1F1 plants of verified putative mutants for disease reaction, a greater number of susceptible plants were observed based on disease severity ratings and other parameters measured. These findings suggest that resistance to Rhizoctonia root rot in mutant barley is inherited as a dominant trait. Given the importance of wild crop relatives to crop improvement, the second experiment involved exploring the possibility of identifying resistance to the disease in the direct progenitor of cultivated barley Hordeum vulgare subsp. spontaneum. Of the entire pool of 317 accessions in the Wild Barley Diversity Collection that was screened for resistance, six accessions showed potential as gene donors for Rhizoctonia resistance with one accession, WBDC 021 showing the greatest potential by displaying moderate resistance to the pathogen.
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Details
- Title
- Identification of sources of resistance to rhizoctonia root rot in mutant and wild barley
- Creators
- Olutoyosi Olubukola Ajayi
- Contributors
- Steven E. Ullrich (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Crop and Soil Sciences, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900525051201842
- Language
- English
- Resource Type
- Thesis