The manipulation of height growth 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 and fruiting 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.
“It’s really interesting that 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,” Strauss said. “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. They were grown in the field with USDA approval, and assessed several times for variation in size and appearance.
Other than reduced size, there appeared to be striking variation in foliage color and leaf shape, some of which might have significant ornamental value. Root development also appeared to be very strong, which might provide increased stress tolerance and have value where extensive root development is needed, such as in bioremediation of polluted soils or in very windy, limited soil moisture situations.
From an environmental viewpoint, the researchers said, dwarfed trees such as this are unlikely to be any kind of threat to spread, because they would compete very poorly with normal or wild trees. In virtually all tree species,
Source:Oregon State University