"The problem with conventional breeding is that you get a mix of the traits from the two parents, so for whatever qualities you're looking for, even if the parent plants have many highly desirable traits, their offspring may not exhibit all of the characteristics the parents have," Meilan said.

A solution, he said, is to find a way to propagate trees without the need for conventional breeding.

"With houseplants, you can take a cutting, put it in water, and it will root. That's called vegetative propagation," Meilan said.

"You can't do that with most trees. If you take a branch off of a walnut tree and stick it in water, it won't develop roots. We'd like to find the genes that cause root initiation so we can develop trees we could propagate, just like houseplants."

This would allow for the production of uniform fields of trees, all with the same suite of desirable characteristics, Meilan said.

The potential to engineer trees and other plants with valuable characteristics is not without controversy, and critics point out the risk of contaminating wild stands of trees with pollen from plants carrying novel genes. An answer to those critics, however, could lie within the process of gene discovery itself, Meilan said.

"If we're domesticating trees, it probably won't be for their flowers; it's for the wood. And if we can propagate them vegetatively, we won't need them to flower," he said. "To prevent gene flow, we could develop transgenic trees that don't flower or that flower at an unusual time.

"This would allow us to achieve what's known as 'bioconfinement' - preventing a gene you've introduced from escaping into the wild."

Meilan said he sees tree domestication as a partial solution to the myriad problems associated with human population growth, such as loss of agr
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Contact: Jennifer Cutraro
jcutraro@purdue.edu
765-496-2050
Purdue University
10-May-2004