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Tyler Van Buren
Abstract:
Tricyrtis
formosana is a rhizomatous herbaceous perennial that is
found in moist woodlands and on cliffs or mountains in areas
stretching from the eastern Himalayas to the Philippines. A
commercial grower in Oregon observed chlorotic blotching
(yellowing) and a slight mosaic pattern on the leaves of
Tricyrtis formosana ‘stolonifera’ a symptomatic plant sent
for diagnosis. The symptomatic Tricyrtis was analyzed
by ELISA using a panel of potyvirus specific monoclonal
antibodies (McAbs). An antibody specific for a highly
conserved site in the potyviral coat protein, PTY1, reacted
with the original symptomatic samples. Total RNA nucleic acid
extracts from infected Tricyrtis were used as templates
for reverse transcriptase polymerase chain reaction (RT-PCR)
with five different generic and/or potyvirus-specific primers
that amplify highly conserved 335 base pair (bp), ca. 700 bp,
and ca. 1100 bp fragments from the coat protein (CP) gene, a
portion of the replicase gene, and the 3’ non-coding region of
most potyviruses. The PCR fragments amplified from the
Tricyrtis plant were subsequently cloned and sequenced.
The sequence information gathered originally indicated that
the nucleotide (NT) sequence had high homology with other
potyviruses. Amino acid comparisons to corresponding segments
of other potyviruses unveiled similarity to Bean Common
mosaic necrosis virus (BCMNV) and many other potyviruses.
Sequence alignments and phylogenetic analysis of the coat
protein amino acid and 3’-end non-coding region sequences of
the virus in Tricyrtis, along with other closely
related viruses, indicate that this virus is distinct, but
most closely related to
Ceratobium mosaic virus (CerMV)
and Bean Common mosaic necrosis virus (BCMNV).
One-on-one comparisons of the CP amino acid and 3’ NCR
nucleotide sequences in the Tricyrtis virus revealed
less than 90.0% identity with other members of the potyvirus
group, which suggests that this virus is a unique member of
the potyvirus group. This is believed to be the first
report of a potyvirus, not to mention any virus infection, in
the genus Tricyrtis.
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