Dec. 8, 1999 La Jolla, Calif. -- A gene that speeds up the maturation process in plants, resulting in earlier development and flowering, has been isolated by a team of scientists at The Salk Institute.
The scientists also describe how to fine-tune the process, so breeders one day could determine how fast or slow they want a plant to pass through its various growth phases.
"Essentially, this gene accelerates the whole life cycle of the plant," said Detlef Weigel, an associate professor of plant biology at Salk and principal investigator of the study.
"And the fine-tuning mechanism is potentially significant for agriculture, helping farmers to regulate crop yield potential and the breeding process."
As described in today's issue of the journal Science, the new gene called FT (for flowering locus T) works independently from LEAFY, the first gene that was shown to cause early flowering on its own.
In those earlier studies, also conducted by Weigel's lab, the transformed plants skipped past normal growth phases that produce long stems and leaves, and moved quickly to flower production.
For example, aspens first bloom when the trees are 30-feet tall, when they're between 8-20 years old. As a result of the experiments with LEAFY, the flowering time for the genetically modified aspens was slashed to a matter of months.
Unfortunately, flowering came so early -- stunting the growth of limbs and leaves -- that the trees ultimately looked more like weeds.
"LEAFY has profound effects on plant architecture," said Weigel. "Plants not only flower early, but all side shoots are converted into single flowers."
In contrast, the new FT gene accelerates all phases of plant growth -- not just flowering.
"In human terms, LEAFY would teach a baby how to read and write, but it was still a baby," said Weigel. "Whereas with the FT gene, every phase of the life cycle goes by much faster and the plants are more like normal plants. It's as if you rapidly turned a baby into a teenager."
For the current studies, Weigel's team genetically modified a scruffy roadside weed called Arabidopsis thaliana, more commonly known as a relative of the mustard plant. Seeds from these plants ended up carrying altered copies of the FT genes.
The scientists found that the protein encoded by FT bore a strong resemblance to another Arabidopsis protein called TFL1, which has an opposite effect on flowering. An increase of FT function causes earlier flowering, but an increase of TFL1 causes later flowering.
Following further study, the scientists concluded that early plant maturation could be fine-tuned by adjusting the expression of FT and TFL1.
"A lot of FT makes plants flower very early, and we can temper that by adding more TFL1," said Weigel. "It acts almost like a hot and cold dial that regulates water temperature in the bath or kitchen."
Weigel said his group already has inserted the gene into tobacco plants, accelerating flowering there. His next step is to create genetically altered rice, a major cash crop.
Also participating in the study, titled "Activation Tagging of the Floral Inducer FT," were Igor Kardailsky, Vipula K. Shukia, Ji Hoon Ahn, Nicola Dagenala, Sioux K. Christensen, Jasmine T. Nguyen, Joanne Chory and Maria J. Harrison. The study was funded by the National Science Foundation and the Samuel Roberts Nobel Foundation.
The Salk Institute for Biological Studies, located in La Jolla, Calif., is an independent nonprofit institution dedicated to fundamental discoveries in the life sciences, the improvement of human health and conditions, and the training of future generations of researchers. The Institute was founded in 1960 by Jonas Salk, M.D., with a gift of land from the City of San Diego and the financial support of the March of Dimes Birth Defects Foundation.
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