REPLY: [pbs] permanent clones??

John Bryan
Wed, 07 Jul 2004 09:37:46 PDT
Dear Dave:

Thanks for your message. Rather than an inner scale, I think the very
tip of the growing point is better in order to obtain virus free cells.
Hopefully they are taken before the virus can get to them, this would be
even more the case if the tissue was taken from a plant that was growing
rapidly, i.e. with added warmth to stimulate fast growth. Cheers, John
E. Bryan wrote:
> In a message dated 06-Jul-04 6:29:39 PM Pacific Daylight Time,
> writes:
> >
> > Clonal selections of Lilium, did recover vigor and lost the virus
> > problem when raised from tissue culture, however in a few years they
> > again lost vigor. Another batch raised from tissue culture lasted for an
> > even shorter period of time. The regained vigor is not permanent even
> > though virus free. Certain genera it seems just get weaker with the
> > passage of time.
> >
> John ~
> Judith Freeman (of Columbia-Platte Lilies and The Lily Garden) has said the
> issue is that meristem culture did not remove all the virus particles in the
> bulbs multiplied by meristem culture.  The remaining few particles were too few
> to be detected by ELISA tests.  For that reason, it is necessary to
> periodically repeat these tests to have any assurance of virus freedom.  What, in
> effect, is happening with these supposedly virus-free lilies is that the
> undetectable virus gradually works itself back up to levels that present the standard
> symptomology.  I would imagine to get a truly virus free lily, one would have to
> continuously to incubate sections of the innermost scales.
> I really know daffodils more than I do lilies and it is common for seedlings
> to be free of virus.  If a given clone is also a prime show flower, it soon
> contracts one or more of the daffodil viruses from careless activities by the
> grower and usually at the hybridizer/commerical grower level.  One prime form of
> spreading daffodil virus is the machine-based Dutch method known as
> "cutting."  A daffodil bulb is sliced into sections (analogous to an orange) by machine
> to be incubated to generate bulblets between the scales and then planted out.
>  While this was a major advance in productivity, it also carries with it the
> seeds of its own destruction.  The cutting head is changed out between clones
> and, often between stocks, but not (obviously) between individual bulbs.  The
> interesting thing with Narcissus and its virus pathogens is that a given clone
> can live for decades in spite of it, blooming and multiplying.
> Dave Karnstedt
> Cascade Daffodils
> Silverton, Oregon, USA
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