North American Fruit Explorers mailing list at ibiblio

["Lon J. Rombough" <lonrom@hevanet.com>]

Mutation breeding is very widespread.  There are very large scientific journals devoted entirely to the process.  It has been studied extensively, and there are ways to use it that even an amateur can do.  For example, pollen can be exposed to ultraviolet radiation from a UV light, then used to pollinate a flower.  That's not very efficient because it's necessary to grow out all the seedlings and it's not always easy to tell what is a mutation and what was just normal variation. 
Chemical mutagens can be used in place of radiation, too.  Caffine is one.  Several cancer drugs are also mutagens, too.  And some of the mutation causing chemicals are very strong cancer causers, as well.
For all of that, the changes they cause are still the same kinds that would occur in nature.  The rate is just pumped up enough to make it possible to find useful ones at a higher rate.
-Lon Rombough
Grapes, writing, consulting, my book, The Grape Grower, at http://www.bunchgrapes.com  Winner of the Garden Writers Association "Best Talent in Writing" award for 2003. 
For even more grape lessons, go to  http://www.grapeschool.com
For growing supplies and more;  http://www.grapegrowersolutions.com

On Aug 28, 2007, at 9:42 PM, Ginda Fisher wrote:

A bunch of apple cultivars were developed by exposing a buds of older cultivars to radiation.  I think that's where a lot of the "spur" type, redder types, and some other variants of popular cultivars come from.  Some are randomly found sports, of course (which are usually the result of natural radiation changing the genes in a bud) but I think a lot were intentionally created.

It sounds like this method is very widespread.