Thesis
Distribution and genetic diversity of seed gall nematodes on Sporobolus cryptandrus in West Central Idaho
Washington State University
Master of Science (MS), Washington State University
2016
Handle:
https://hdl.handle.net/2376/100963
Abstract
The genera Anguina and Afrina are plant parasitic nematodes associated with lesions on stems, leaves and seeds in grasses and small grain cereals. Anguina species can act as vectors of Rathayibacter spp., carry them into plants, resulting in gummosis diseases of grasses and wheat worldwide. This study aimed to better understand the prevalence and distribution of seed gall nematodes in the Pacific Northwest (PNW) region of the U.S. and consequently of associated Rathayibacter spp. We used nuclear and mitochondrial markers to estimate the genetic diversity of seed gall nematodes of the species associated with Sporobolus cryptandrus in West Central Idaho. Forty-six samples from S. cryptandrus hosts collected in West Central Idaho were positive for seed gall nematodes and Rathayibacter sp. was isolated from all bacterial and some nematode galls. The analysis of the ITS region and the D2/D3 expansion segment of the 28S rDNA gene supports the hypothesis of a new species of seed gall nematodes on S. cryptandrus in Idaho. Phylogenetic analysis of the ITS region showed that the seed gall nematodes extracted from S. cryptandrus belong to the genus Afrina and may represent a new species. More genetic variation occurred in the partial cox1 gene of the mtDNA than in the ITS region and D2/D3 region of the 28S rDNA gene among nematodes from S. cryptandrus. Sequence divergence of the partial cox1 gene and haplotype network of the seven haplotypes of the nematodes extracted from S. cryptandrus indicates substantial genetic differentiation between haplotype H3 and all other haplotypes. However, nematodes with sequence divergence of 5.2% can be considered to belong to the same species. Phylogenetic trees based on the ITS region indicated that the species found in Agropyron smithii collected from New Mexico belongs to the species Anguina agropyronifloris and the species found in Agrostis sp. collected in Washington belongs to the species Anguina agrostis. Morphological and morphometric studies are needed to describe the new species and to confirm the species of the other two Anguina species.
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Details
- Title
- Distribution and genetic diversity of seed gall nematodes on Sporobolus cryptandrus in West Central Idaho
- Creators
- Bianca Leonor Barrantes Infante
- Contributors
- Timothy D. Murray (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Plant Pathology, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525068001842
- Language
- English
- Resource Type
- Thesis