Scientists said on Wednesday they had sequenced all the genes of a weedy relative of the mustard plant in an achievement they say will not only transform plant biology and agriculture but will help human medical research.

The plant, Arabidopsis thaliana, is a favorite of laboratory researchers, who say it is as important to plant science as the mouse is to human medical science. It is the first plant to have its genome sequenced.

The international team of researchers who worked together to sequence all 26,000-odd genes in the scraggly weed, commonly known as thale cress or mouse ear cress, said they were immediately launching a 10-year project to find out what each and every gene does.

"The completion of the Arabidopsis genome sequence has profound implications for human health as well as plant biology and agriculture," Robert Martienssen, a researcher at Cold Spring Harbor Laboratory in New York, who helped organize the sequencing effort, said in a statement.

PLANT GENES RELATE TO HUMAN DISEASE

"Plants have many of the same genes as people do," he added at a news conference. For instance, Arabidopsis has the BRCA1 and BRCA2 genes that can, when mutated, cause breast cancer.

"Our analysis shows that there are about 100 genes in Arabidopsis that are very closely related to human disease genes -- diseases such as hereditary deafness, blindness and cancers," Mike Bevan of the John Innes Center plant research center in Cambridge, England told a news conference in London.

Being able to work with genetic information can also transform agriculture -- something that will become more and more important, Martienssen said. "By the year 2050, it is predicted there will be 10 billion people on this planet," he said. "They will need food, fiber fuel."

Genetic engineering, the researchers said, can speed up the process pre-Columbian populations started in the Americas when they figured out how to breed corn from a top-heavy grass.

For instance, said Rita Colwell, head of the National Science Foundation, more precise genetic modifications can create better drought-resistant crops, vegetables that fend off pests and super-producing plants, while genomics can predict what, if any, effects these changes might have on the environment and on the people and animals that eat the plants.

"What took decades of very careful breeding and selecting will now take just a few months," she told the news conference.

Sequencing the genome of any organism -- its entire collection of genes -- is only the first step to understanding its genetics. DNA is a repetitive code. While scientists now have all the letters in the code, it will take years to sort out how that code spells out the book of life.

Arabidopsis, with its thin stem, small green leaves, and tiny white blooms, has no commercial, medicinal, decorative or food use. But it grows easily in labs and is simple from a genetics viewpoint, making it a darling of plant scientists.

"It seems somewhat ironic that a lowly weed has become one of the most important plants on our planet," Clare Fraser of the Institute for Genomic Research, who worked on the study, said.

"One reason the plant was chosen was because it doesn't have that much DNA," Elliot Meyerowitz, a plant geneticist at the California Institute of technology (Caltech), said in a statement.

SEQUENCE WAS A 'BARGAIN'

"Arabidopsis has about 125 million base pairs in the entire genome -- and that's 20 times smaller than the human genome, and thus about 20 times less expensive to sequence. It's been a bargain."

Base pairs make up the "rungs" on the twisted ladder of DNA. Each is represented by a letter -- A, C, T or G -- that stands for one nucleotide, the chemicals that make up DNA.

Scientists now have the full, repeated readout of As, Cs, Ts and Gs but have yet to decipher what they say.

The same is true of the human genome, which was sequenced just this year. The human genome has 3.1 billion base pairs of code, but scientists aren't sure just how many genes this translates into although they think it is somewhere between 60,000 and 80,000.

But genome sequencing is the first step to understanding from the ground up how an organism works.

So widely important is Arabidopsis that 300 scientists in Europe, the United States and Japan worked together to figure it out. The sequence itself is published in the journal Nature as well as on the Internet and papers on some of the clues that are already being found are in next week's issue of the journal Science.

They started in 1996, using a slow and painstaking process that they say has produced a highly complete and accurate picture of the plant's genetics, unlike the "whole-genome shotgun sequencing" that was used to sequence the human genome in just a few months this year and last.

Just as mice are closely related, on a genetic basis, to humans, Arabidopsis is closely related to rice, wheat, barley and many other plants that are of huge importance to agriculture and medicine.

(From ChinaDaily)