The Test

   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:

   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.