Does a Virus
Cause White Veins?
Bill Meyer, Woodbury, Connecticut
It was back in 1997 that Americans saw
their first white-veined hosta. A division of 'Amime-no- Tachi', an H.
selection from Japan,
was donated to the auction at the AHS convention in Portland, Oregon by
Bette Comfry, who was then the proprietor of Silvermist Nursery, one of
the best hosta specialty nurseries of its day. The high bid on it was
Soon after, the plant was thought by many to appear
unhealthy and so was tested at AHS expense and found to have an unknown
virus. The plant was then replaced with another of the same variety
brought from Japan, and Mrs. Comfry reimbursed the AHS for the refunded
money. The following year, both the infected one and the
healthy one were on display in the auction winner's garden, which was on tour for the AHS
convention in Indianapolis. The virus- infected plant showed much of the
white-veined look, while the healthy replacement plant was mainly just
green. The photo, at right, shows the virused plant as it appeared on
the first one
| The presence of an
unknown virus in
that first white-veined plant led many to reasonably suspect that the
white veins in 'Amime-no-Tachi' were a symptom of virus infection
rather than some new mutation. Their caution was well placed, as the
HVX epidemic began a few years later and virus-caused symptoms quickly became
the biggest news of the new century. To this day, nurseries have been
wary of propagating white-veined plants because of the possibility
that the variegation might be caused by a virus or other pathogen.
this time, W. George Schmid had a division appear on an H. rectifolia
seedling with a very similar look. He named it 'Gosan Line Up'.
This plant caused quite a bit of discussion at the time, but
eventually lost its variegation, becoming simply another
plain-green seedling. George writes about it and some other
white-veined plants in the H. rectifolia Pt. 2 segment of
his thorough and scholarly species descriptions found at the HostaLibrary. It did lose
its variegation by the time of the study, but was included in the
test because if a virus was responsible it should still be present
in the plant.
| Next to arrive on the
American hosta scene was 'Mito-no-Hana', a smaller sieboldii
derivative with even better and more stable vein marking. It also
came from Bette Comfry's collection of Japanese hostas. Bette had
lost her husband and her own health was beginning to fail, so she
closed Silvermist in the late '90's. She offered her Japanese
Van Wade, where the plants are today. The first pieces of 'Mito-no-Hana' began to become
available shortly into the new century.
It's first appearance in an AHS convention auction in
2005 brought a winning bid of $1,000 from Bob and Barbara Tiffany,
who featured it in their garden when it was on tour for the 2006
convention. Seedlings from it are reported to not show the white
|| In 2009, Stan Megos,
proprietor of the Variegated Foliage Nursery, entered a new
white-veined sport that he had found at the nursery in the First
Look Seedling and Sport Competition and won the Frances Williams
Award with it. He decided to name his find 'Yikes Stripes'. It is
a chance seedling of unknown heritage, but appears to resemble H. yingeri.
He plans to make it available soon.
| Also, in
2009, word began to circulate about the most exciting white-veined
plant to date, a 'Honeybells' sport found on his large old clump by Gerry Bennet that he
calls 'Second Coming'. Gerry is a friend of hybridizer, Rick
Goodenough, and Rick mentioned the plant on Rod Kuenster’s Hosta
Seed Growers forum, causing quite a stir when he later showed
pictures. There is much interest in this plant, and it was
auctioned once for fundraising and fetched $310. My bet is that
'Second Coming' will be the first white-veined hosta to become
widely available - if the appearance isn't caused by a
latest to appear was Deb Abrams' 'Electric Love', which made its
debut at the 2010 First Look meeting. It appears to be yet another
sport, and the variegation appears to be more of a yellow color
than the others. Deb is still considering what to do with this one
and has not yet shared a piece.
| These six plants are, as of
this writing, the best known of
the white-veined types, but others have appeared here and there with
less fanfare. It is possible none of those survive, as of this
writing. Some were, no doubt, destroyed because of the danger that they
could be infected with some as-yet-unknown virus or other pathogen. A
white-margined plant with white veins turned up in the late
1990's, but hasn't been seen or talked about since.
Over the years we've had a
few of these white-veined plants being donated to the First Look Online
Auction that we run every winter. They've been something of an issue
each time because those who thought the variegation might be caused by a
virus were concerned about them being auctioned. Certainly they had a
point; the cause was unknown and did bear some resemblance to the
symptoms of the "vein clearing" group of viruses.
It was a difficult decision, but we did decide to include
them in the auction because there was no proof of any kind that a virus
caused the pattern, and because there were real differences between what
we saw in these hostas and the vein clearing symptom. In the latter
plants, the veins appeared a translucent greenish yellow, about what
you'd expect if the chloroplasts were destroyed. In these hostas, the
veins were an opaque white or cream color, indicating the presence of
white and yellow
pigments, and, further, they usually "greened up" during the
season with their best color early in spring. That would require
"repair" if the cloroplasts had been destroyed- an unlikely
scenario. These observations seemed to strongly
indicate that it was a mutation of some kind, and not disease symptoms.
Still, the question of a virus remained on the table, so I
organized a study in which Dr. Ben Lockhart, one of the world's top
plant virologists, would investigate it for us. This study was funded by
Region One of the AHS. This past July, I sent a sample of 'Amime-no-Tachi';
Rick Goodenough sent 'Second Coming'; Debra Abrams sent 'Electric Love';
Rod Kuenster sent 'Mito-no-Hana'; and George Schmid sent the now-green 'Gosan
Line Up'. We were unable to obtain a sample of 'Yikes Stripes', but the
five would serve for the first tests.
After just a few days, I
received word from Dr. Lockhart. What he had to say should lay the
question of the white veins being caused by a virus to rest. He prepared
samples from the leaves that were sent and viewed them under the
electron microscope at the University of Minnesota. The remarkable
magnification produced by an electron microscope is capable of would
clearly make visible to Dr. Lockhart's trained eye any virus particles
present in the samples. It wouldn't matter whether the virus was an
unidentified new one or one he was familiar with; any virus present
would be visible.
Here is what he had to say about the test results:
"Leaf samples of the following hosta cultivars were received
last week and were tested for presence of virus by transmission
electron microscopy (TEM), using partially-purified leaf tissue
extracts prepared by ultracentrifugation.
2. 'Second Coming'
3. 'Electric Love'
4. Reverted H. 'Gosan Line Up'
No viruses of any kind were detected in the first four
samples. The sample of 'Amime-No-Tachi' contained a high
concentration of filamentous virus particles, identified as those
of Hosta virus X (HVX), by enzyme-linked immunosorben assay
(ELISA). No foliar nematodes were detected in the necrotic tissue
along the petiole and some lateral veins of this sample.
The results obtained suggest that the presence of white
veins in these host genotypes are probably not associated with
infection by HVX or any other virus. I hope that this information
will be of use to you, and I would be very happy to provide any
additional information on the virus testing procedures used.
Ben E. Lockhart, Professor
Department of Plant Pathology
University of Minnesota
St. Paul, MN
These results indicate
that, in the samples provided, which are five of the six better-known
white-veined hostas, there are no virus particles of any kind to be
found, save one plant which was infected with HVX. The HVX-infected
plant has never shown any of the known HVX symptoms, and is very likely
a division of that very first 'Amime-no-Tachi' plant that was found to
have a virus. The infected plant traces back directly to that one,
indicating that that initial test probably was the first discovery of
HVX in a hosta.
Because nothing was found in the other samples, each of
which, save 'Gosan Line Up', was well variegated, it seems clear that
the white veins are not caused by any virus known or unknown. The source
of this variegation remains a mystery, but is apparently the result of a
mutation of some kind. Curiously, two attempts to tissue culture 'Amime-no-Tachi'
failed to produce any variegated plants. Even after a few years of
growth, no white veins appeared, yet normal division has always resulted
in variegated plants. As of this writing, there is a rumor that another
white-veined hosta is being TC-ed. If it also fails to produce
variegated plants, the white-veined hostas may forever remain the stuff
of collectors' desires.