LOS ANGELES, June 18 (Xinhua) -- Researchers at the Oregon State University (OSU) have used genetic modification to successfully manipulate the growth in height of trees, according to a new study.

In their studies, OSU scientists were able to change poplar trees, which normally grow rapidly and can reach a mature height of 150 feet or more, into new breeds that are anywhere from about 15 feet to a few inches tall after two years of growth.

The smallest of them could be difficult to be found, according to the study published by the latest issue of the Landscape Plant News journal.

The manipulation of tree height was achieved by insertion of certain genes, mostly taken from the model plant Arabidopsis, which inhibited the action of a class of plant-specific hormones known as gibberellic acids.

These compounds are also used as sprays to control the size andfruiting of orchard trees. In trees, the compounds promote the elongation of plant cells when they are inhibited. The cells do not fully elongate, and plants remain short and stocky.

These genes from Arabidopsis, which is a small plant in the mustard family, have been conserved through 50-100 million years of evolution and can perform more or less the same function in poplar trees. The modified trees themselves look pretty much normal, just a lot smaller, and a little more compact or bushy.

Altogether, the researchers used seven distinct kinds of genes and more than 160 different types of genetic insertions to create about 600 genetically modified trees. All caused decreased signaling by gibberellic acids.

This is a proof of concept that tree height can be readily controlled by genetic engineering techniques, experts said.

It opens the door to a wide variety of new products for the ornamental and nursery industries if regulatory hurdles can be overcome, experts say.

"From a science perspective, this is a very interesting accomplishment and there is no doubt it could be made to work," said Steven Strauss, a professor of forest science at OSU.

But further development may be precluded by social, legal and regulatory obstacles, he said.

"Clearly there would be concerns whether the market for specialty tree products such as this would be strong enough to make it worth the large investments of time, money and testing that current regulation of genetically modified organisms would require, at least in the U.S.," Strauss said.

That aside, he said, it appears that with further research and development programs, it would indeed be possible to create an elm tree which ordinarily would grow to 100 feet or more that is only five feet tall at maturity, a charming addition that would fit nicely on a backyard deck.

Or a 30-foot version that might be a better fit on urban streets. Or, in fact, just about any height in between. Other changes can also affect foliage shapes or color in very attractive ways, and some might have value in cleaning up environmental pollution.