The influence of genetic and environmental factors on morbidity and mortality in populations of butternut affected by butternut canker disease
Butternut (Juglans cinerea L.), or white walnut, has suffered large population declines in the past half-century due to poor regeneration and mortality caused by an introduced fungus, Ophiognomonia clavigignenti-juglandacearum (Nair, Kostichka & Kuntz) Broders & Boland. This fungus causes branch and trunk cankers that can coalesce to girdle adult trees. Chapter 1 provides background information on butternut and butternut canker. We used next-generation sequencing to identify new nuclear DNA markers for butternut and Japanese walnut, a congener with which butternut readily hybridizes. We also examined the alignment of SSR repeat sequences in butternut and Japanese walnut with similar sequences from other angiosperms in public sequence databases. The methods used and results obtained in this process are detailed in Chapter 2. Chapter 3 summarizes an investigation of the environmental and genetic factors contributing to canker disease incidence, severity, and mortality in a large (n=113) population of butternut in southern Wisconsin and two other populations of butternut, one near the main study site in southern Wisconsin and another in the Great Smoky Mountains National Park. We present evidence for weak correlations of genetic similarity and phenotypic similarity for several disease traits, parentage analysis of regeneration in the smaller Wisconsin population, and evidence for significant microsite influences on butternut mortality over an 11-year period in the large Slocum's Woods butternut population.
Woeste, Purdue University.
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