REPLY: [pbs] permanent clones??
Tue, 06 Jul 2004 20:19:55 PDT
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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