Long Day's Journey into Flower

17 April 2003 (All day)

Lit up. Rice and a common weed have the same genetic systems for flowering--but one gene makes all the difference in their behavior.

Despite their differences, rice and the commonly studied mustard weed share closely related flowering mechanisms. The finding suggests that there may be a common flowering control among plants. The finding might eventually allow scientists to manipulate genes in rice and other crops to enhance production.

Arabidopsis thaliana has been a popular model plant with biologists. Sequencing the Arabidopsis genome in 2000 helped researchers pinpoint three genes that compel it to flower. The weed doesn't blossom until daylight lingers during spring and summer days, making it a "long-day" plant. Geneticists working with rice, a "short-day" plant, wanted to know whether it relied on the same genes to flower.

The answer, researchers from Japan's Nara Institute of Science and Technology in Ikoma and the National Institute of Agrobiological Sciences in Ibaraki found, was mostly yes: The same three genes helped guide flowering in rice and Arabidopsis. The team did find one key difference, however. In Arabidopsis, a gene called GIGANTEA activates a light-sensitive gene that sets off the blossom-triggering gene. In rice, GIGANTEA suppresses these two, the team reports in the 17 April issue of Nature. Rice geneticist Ko Shimamoto, the lead author, foresees manipulating this genetic pathway, which could extend the growing season or provide ornamental flowers year-round. Shimamoto cautions, however, that other conditions such as temperature will play a role in flowering behavior.

Gordon Simpson of the John Innes Centre in Norwich, U.K., says the ability to change plants' lighting preferences won't come soon, but that this work "validates Arabidopsis as a model" for other plants. In addition, says evolutionary biologist Johanna Schmitt of Brown University in Providence, Rhode Island, the research demonstrates that "you have conservation of the same pathway in very different organisms," but that a small difference in how genes function leaves the plants reacting very differently to light.

Related sites
Ko Shimamoto's Web page
The Arabidopsis Information Resource
Arabidopsis, the Rosetta Stone of Flowering Time?

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