Scientists have first map of plant DNA

The Washington Post

WASHINGTON — Capping a massive international five-year effort, scientists have for the first time identified and placed in order virtually all of the approximately 120 million units of DNA that together spell out the genetic instructions for making a plant.

The feat marks only the third time that a complex organism has had its entire genetic code revealed, following the recent unveilings of the genomes of a tiny soil-dwelling worm and a fruit fly. (The human genetic sequence has been largely completed, but details of that work have yet to be published.)

The new work paints the clearest portrait yet of what it means to be a flowering plant, a unique class of life that arose from a flowerless world a mere 200 million years ago and quickly came to dominate virtually every ecosystem on Earth. It sheds light on how plants diversified and adapted, and in particular how they overcame the unique problems that come with being rooted to a single spot, unable to flee or hide.

More practically, since all flowering plants from broccoli to roses to towering oaks are genetically similar to the species of plant that was studied — a common roadside weed in the mustard family — scientists now have a genetic toolbox that will allow them to tinker with an entire kingdom of life upon which all animals, including humans, are directly dependent.

That could greatly accelerate ongoing — and in some cases controversial — efforts to engineer crops that are exceptionally nutritious or resistant to insects, and to develop plants that can detoxify soil contaminants or make novel medicines or biodegradable plastics in their leaves.

"It’s like standing on top of a hill and seeing gold mines everywhere," said Elliot Meyerowitz of the California Institute of Technology in Pasadena, a pioneer in the field whose work has helped reveal how silken flowers sprout from woody stems, why different flowers have characteristically different numbers of petals, and how flower genes can influence the eventual size of a plant’s edible fruits.

Among the many surprising findings, described in eight articles published in the latest issues of the journals Nature and Science, is that flowering plants have an astonishing array of "senses" — far more, it seems, than people have — with which they can detect and respond to what is happening around them.

Also unexpected, flowering plants have nearly identical versions of many human disease genes. That discovery is already giving researchers clues about why certain human diseases produce the symptoms they do. It suggests that plants may eventually be useful not only as a source of novel medicines but also as a screening tool to test the efficacy of experimental drugs for human ailments. Plants are, after all, much easier and cheaper to grow than mice.

"This is like a Rosetta Stone that will allow us to compare all other living things on Earth," said Peter Raven, director of the Missouri Botanical Garden in St. Louis. "It will lead us to discoveries that are unimaginably interesting."