Pallidosis is a disease of strawberry identified in 1957 with an unknown etiology.
Two previously uncharacterized viruses in strawberry, Strawberry pallidosis associated
virus (SPaV) and Beet pseudo-yellows virus (BPYV), have been found associated with
disease symptoms. The complete nucleotide sequence of both viruses was determined and
molecular detection protocols developed. In addition, an immunological tissue blot assay
was developed for SPaV. Phylogenetic analysis of SPaV placed it in the genus
Crinivirus, family Closteroviridae, along with BPYV. Transmission studies identified
Trialeuroides vaporariorum, the greenhouse whitefly, as a vector of SPaV, while the virus
was not transmitted by pollen or seed. The geographic distribution of both SPaY and
BPYV in the United States was examined.
Two ilarviruses of strawberry were investigated. Tobacco streak virus (TSV) is
the type member of the genus Ilarvirus, family Bromoviridae, and can cause severe yield
losses in small fruit crops. Sequence and phylogenetic analysis of 15 "TSV" isolates from
Fragaria and Rubus revealed that they are homogeneous and represent a new virus
species designated as Strawberry necrotic shock virus (SNSV). Nucleic acid-based
protocols failed to identify any plants of the study infected with TSV an indication that
the virus may not be a pathogen of Fragaria and Rubus.
Fragaria chiloensis latent virus (FC1LV) is the second member of the genus
Ilarvirus that infects strawberry. Previously, the virus had been found only in Chile and
although many plants have been tested in North America using a serological test, none
was found infected with the virus. A molecular test has been developed and used to
confirm the presence of the virus in strawberries along the west coast of North America.
Phylogenetic analysis of the coat protein gene of the virus place it in subgroup 4 of the
genus along Prune dwarf virus, while it was previously thought to be related most closely
to Lilac ring mottle virus and Asparagus virus-2.
The role of the newly identified viruses and other viruses infecting strawberry is
discussed in association with the strawberry decline disease found to cause severe
symptoms and yield losses in both California and British Columbia, Canada.
The significance of the work presented in this publication includes: the
identification of two viruses associated with strawberry pallidosis disease; the complete
nucleotide sequence of two criniviruses, an emerging group of plant viruses adds to the
limited knowledge we have about this diverse virus genus; the identification of FC1LV in
North America; the identification of SNSV as a distinct virus species which demonstrates
the need of further studies on TSV, a virus species that infect a wide range of plant
species and may actually be a cluster of diverse species. The high incidence of the
pallidosis associated viruses points to the significance of the disease and their role in
strawberry decline. The development of fast, sensitive and reliable tests for four
strawberry viruses will have an impact to the strawberry industry, since the need for high
quality, virus-free plants is essential for a crop that is asexually propagated. / Graduation date: 2004
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/30576 |
| Date | 19 March 2004 |
| Creators | Tzanetakis, Ioannis E. |
| Contributors | Martin, Robert R. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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