Plant biologist weeds through ‘junk’ DNA

MCGILL (Canada)—Those little green “weeds” that pop up in sidewalk cracks may shake up the world of plant biology, if Thomas Bureau, a researcher at McGill University in Montreal, has his way.

The plant is Arabidopsis, or rock cress. It’s a flowering plant from the same family as cauliflower and cabbage, but with a much simpler genetic structure, making it ideal for genetic research. Bureau and his colleagues are using the plant to explore the part of the genome previously dismissed as “junk DNA.”

Bureau is convinced that the sizable field of junk, or non-coding, DNA plays a role in an organism’s genetic makeup.

“A lot of data that’s been growing within the community seems to show that this so-called ‘junk DNA’ actually has important functions in terms of cell development and maintaining the organism,” Bureau says. “And in this case, it has agronomic importance. Those particular regions within that sea of junk DNA might be important for agronomic traits like freezing tolerance or nitrogen-use efficiency. No one’s really done a systematic survey, let alone exploit that information. So we don’t really even know what’s in that DNA. It’s a true no-man’s land.”

Two trays of Arabidopsis plants removed from a growing chamber seem to bear out the importance of this previously ignored area.

The control group is perfectly normal, straight and tall, if tiny. But the experimental group, subject to a single genetically engineered change within the non-coding DNA, are noticeably different: shorter, twisted, their flowers misshapen.

“Something is obviously happening here,” says Bureau. “Because the only change we made was to the non-coding DNA, and it clearly affects how the plant grows and looks. How is that in any way ‘junk’?”

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