North American Fruit Explorers mailing list at ibiblio

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On Jun 16, 2004, at 12:44 PM, Rob Halgren wrote:

> > Ginda, Does this mean they are examining sequences after each 
> > successful
> > fertilization, or that they are using some Genetic Engineering 
> > concepts and
> > practices to achieve this end? In relation to wild breeding 
> > populations, an item
> > which has not been addressed is hand pollination in breeding has many 
> > downsides.
> > Natural flower structure differs from flower to flower, with some 
> > flowers being
> > unable to fertilize under normal conditions. ie insect/wind. Various 
> > parts can
> > have flaws only revealed under a microscope. By hand pollinating the 
> > number of
> > these types of flowers is likely to increase, debilitating the plant 
> > in future
> > generations. This has been recognized first with vegetable 
> > breeding/preservation,
>
> 	It isn't at all difficult to examine all the seedlings for the 
> presence of the genetic marker they are selecting for.  A few grams of 
> tissue, some reagents, and a thermocycler are all you need.  It is 
> cheap, too. Or at least it is now.  If I recall, they are using 
> standard breeding techniques, and selecting the seedlings to grow to 
> breeding size.  If they did that right, they could raise a large 
> number of otherwise genetically diverse trees to breeding size.
Yes, that's what I've heard.  I would call this a "genetic engineering 
concept", but they are using conventional breeding, not transgenic 
methods.  The testing has apparently been a huge boon to the project, 
because previously they had to raise plants to the age where they show 
symptoms of disease, and now they can select resistant seedlings to 
grow on.

They are using at least a little hand pollination.  This year they were 
recruiting volunteers to bring hybrid pollen into the woods during 
flowering season.  American chestnuts keep growing back from the roots, 
and a A few of them flower for a year or two before they die of blight. 
 The goal is to pollinate those rare flowers with resistant pollen, in 
the hopes of including as much native genetic material as possible.


> > > I still wonder whether the Chestnut will ever be more than 
> > > functionally extinct,
> > > since its habitat niche has been filled by other species in the last 
> > > 50+ years.
>         
Well, it's mostly been replaced by oaks, which I expect will be 
endangered by sudden oak death in another decade, so there might be a 
big 'ole niche open for it.  But perhaps I am too pessimistic.
(I don't know about plants, but the peregrine falcon and bald eagle 
have both made comebacks with a little help from their friends.)

Ginda