Electronic Thesis and Dissertation Repository

Degree

Master of Science

Program

Biology

Supervisor

Dr. Aiming Wang

2nd Supervisor

Dr. Mark Bernards

Joint Supervisor

Abstract

Greenhouse vegetable production is a very important and successful agricultural sector in Ontario. However, newly emerging viral or virus-like diseases have become a major limiting factor in greenhouse vegetable production. To determine the identity of the viral pathogens in the three major greenhouse vegetables in Ontario, we conducted in-depth sequencing of small RNAs isolated from virally infected plants used next-generation sequencing technology. Subsequent bioinformatics analyses revealed six viral pathogens including Bell pepper endornavirus (BPEV), Parietaria mottle virus (PMoV), Cucumber green mottle mosaic virus (CGMMV), Tobacco streak virus (TSV), Pepper mild mottle virus (PMMoV), and Pepino mosaic virus (PepMV). The full-length genome sequences of BPEV, PMoV, and CGMMV have been cloned and sequenced.

Since CGMMV causes the most severe economic lossess, we further characterized CGMMV and constructed an infectious CGMMV clone for the development of an attnuated virus for the control of CGMMV. We found that in the mimic greenhouse hydroponic production system, CGMMV is water-transmissible. We introduced various mutaitons into the CGMMV infectious clones and tested their infectivity. Our data demonstrated that when host plants were infected by two particular mutants MRTAL and MGVDT, no symptom appeared on the systemic leaves and viral RNA or coat protein accumulation level was low. Based on these data, we suggest that the mutants MRTAL and MGVDT have great potential to be used as attenuated CGMMV variants for cross protection against CGMMV.


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