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  • From: Rob Halgren <halgren@msu.edu>
  • To: nafex@lists.ibiblio.org
  • Subject: [NAFEX] Re: chestnuts
  • Date: Wed, 16 Jun 2004 12:44:41 -0400


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.

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.


For example the Green Ash, which has been almost exterminated by emerald ash borers in SE Michigan? You won't find an ash bigger than a few inches in diameter in a large portion of the state - the ones that the borers didn't get the state is cutting down to prevent the spread of the critter. I'm not sure they are succeeding. So, since a lot of those ash trees were planted to replace american chestnut and elm, it seems only fitting to replace them with blight resistant chestnut. I'm not too worried about our 'natural' forests in michigan - most of them are a)managed, and b)pretty diverse. I'm sure that blight resistant chestnut would be planted in these managed woodlots, it will spread from there (assuming there are any unmanaged woodlots by then).

Of course at some point people will get smart and start planting a diverse arrangment of street trees. I lost 5 large elms last year to dutch elm disease (or something like it - could have been another pathogen) - because 40 years ago someone thought it would be nice to have every shade tree in the yard the same species. Now if he had planted two or three species I might still have some trees. I still have a box-elder, but nuclear winter wouldn't kill those. My inlaws live in an older subdivision where every other street was planted in blocks - so some streets have just been completely denuded of ash trees, which they are replacing with maples, of course. Exploding maple disease will take care of that in 10 years, probably.

I am a magnet for plant pests. When I lived in Chicago it was my neighborhood that was decimated by asian long-horned beetles. Very few trees left standing, after the city went through with its containment strategy. I've been to California a few times in the last couple years, but I'm not taking credit for sudden oak death (not yet, anyway).

Rob (good year for big strawberries. Too much water though - big isn't necessarily tasty)

--
Robert G. Halgren, Ph.D.
Bioinformatics Specialist
GTSF - Michigan State University
http://genomics.msu.edu
(517) 353-7236 - halgren@msu.edu




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