In the annual plant Arabidopsis, the first plant to have its genome sequenced, the genes Constans (CO) and Flowering Locus T (FT) induce flowering in response to day length. It turns out that Populus trees (aspens, cottonwoods, poplars), the first tree to have been sequenced, also have CO and FT genes and can be forced to flower in months, rather than years.
The discovery is being reported in Science magazine on-line (Science Express www.sciencexpress.org) on May 4, 2006, in the article, "The Conserved CO/FT Regulatory Module Controls Timing of Flowering and Seasonal Growth Cessation in Trees," by Henrik Bohlenius, Tao Huang, Laurence Charbonnel-Campaa, and Ove Nilsson of the Umea Plant Science Centre at the Swedish University of Agricultural Sciences; Amy M. Brunner of the forestry department at Virginia Tech; Stefan Jansson of the Umea Plant Science Centre at Umea University; and Steven H. Strauss of the forest science department at Oregon State University.
"In this study, we looked at a poplar homolog of the gene FT, which has been shown to regulate flowering in annual plants. Surprisingly, we found that this gene not only controls the multi-year delay in flowering in trees, but also controls seasonal growth cessation and bud set," said Nilsson, the corresponding author of the study.
The Swedish scientists over expressed FT in poplar, and observed normal flowers on six month old trees -- in a tree species that ordinarily takes 8 to 20 years to flower.
Why does it take trees so many years to flower? Brunner and Strauss -- who have been doing research to make genetically engineered trees sterile so that they cannot cross with wild trees -- used consecutive years of poplar clon