Thesis
Investigating virus-host and virus-virus interactions using Iris yellow spot virus and Tomato spotted wilt virus (Tospovirus ; Bunyaviridae) as models
Washington State University
Master of Science (MS), Washington State University
2012
Handle:
https://hdl.handle.net/2376/102460
Abstract
Tospoviruses (Tospovirus; Bunyaviridae) account for major economic losses in terms of both yield quantity and quality in numerous field and horticultural crops worldwide. Sensitive molecular assays were developed to investigate virus-host and virus-virus interactions in planta using Iris yellow spot virus (IYSV), which causes localized infections, and Tomato spotted wilt virus (TSWV), which causes systemic infections, as model tospoviruses, with Datura stramonium as the model host. For virushost interactions, the distribution and accumulation of the nucleocapsid (N) gene of each virus were determined in individually inoculated D. stramonium. To investigate the interactions between the two viruses in the same host, the viruses were simultaneously inoculated and the distribution and levels of each virus determined. Quantitative real-time PCR showed that TSWV was capable of replicating in inoculated and spreading to all tested non-inoculated leaves. In contrast, the host restricted IYSV only to inoculated leaves; no IYSV N gene was detected in the noninoculated leaves. There was no change in terms of distribution or titer levels of TSWV in dually infected plants. However, in the presence of TSWV, IYSV overcame the host defense system and spread to some non-inoculated leaves. In addition, IYSV titers increased more than 1000-fold in inoculated leaves in the presence of TSWV. To further investigate if IYSV was exclusively dependent on TSWV gene products for movement, qPCR protocols were developed for analysis of IYSV movement protein (NSm) and silencing suppressor (NSs) gene expression. The IYSV NSs gene was detected in all the samples while NSm was only expressed in 8% of the samples. Overall, these results suggest that IYSV is only capable of overcoming D. stramonium defense mechanism in the presence of TSWV. A unilateral type of synergistic interaction is evident between IYSV and TSWV, and only the former benefits. However, at this stage it is not clear whether it is exclusively the TSWV NSm gene, or both NSs and NSm, that is required for IYSV movement. This interaction could have economic and epidemiological impact by significantly reducing yield and increasing vector transmission efficiency. The assays are useful in studying virus-host interactions at the molecular level.
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Details
- Title
- Investigating virus-host and virus-virus interactions using Iris yellow spot virus and Tomato spotted wilt virus (Tospovirus ; Bunyaviridae) as models
- Creators
- Nomatter Chingandu
- Contributors
- Hanu R. Pappu (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, Wash. :
- Identifiers
- 99900525095801842
- Language
- English
- Resource Type
- Thesis