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Dartmouth researchers find gene that is key to plants’ iron absorption

  • Mary Lou Guerinot compares lab-grown Arabidopsis thaliana nourished with a sufficient level of iron, at left, and grown in a medium lacking sufficient iron, at right, in her lab in Dartmouth College's Life Sciences Center in Hanover, N.H., Friday, Dec. 13, 2019. (Valley News - James M. Patterson) Copyright Valley News. May not be reprinted or used online without permission. Send requests to permission@vnews.com.

  • Research scientists Sun A Kim, left, explains the process for separating the roots from Arabidopsis thaliana plants to lab manager Anne Lichtner so they can investigate how the different plant parts react to being grown in media with more or less iron at their Dartmouth College lab in Hanover, N.H., Friday, Dec. 16, 2019. Kim was the first author of a study by the lab published in Proceedings of the National Academy of Sciences on how plants turn on genes to increase the absorption of iron in conditions where it is scarce. (Valley News - James M. Patterson) Copyright Valley News. May not be reprinted or used online without permission. Send requests to permission@vnews.com.

  • Lab manager Anne Lichtner separates sprouts of lab-grown Arabidopsis thaliana to be grown either iron sufficient or iron deficient conditions. Researchers hope to use their findings on how plants absorb iron to increase the amount of the mineral in some staple foods. (Valley News - James M. Patterson) Copyright Valley News. May not be reprinted or used online without permission. Send requests to permission@vnews.com.

  • Mary Lou Guerinot, professor of biological sciences at Dartmouth College, left, is the principal investigator of a study that discovered a gene controling iron absorption in plants. Guerinot checks in with graduate student Nabila Riaz, middle, and undergraduate Sophie Skallerud, right, as they work on confirming the genetic mutation of a batch of Arabidopsis thaliana seeds before using them in experiments in the Hanover, N.H., lab Friday, Dec. 13, 2019. (Valley News - James M. Patterson) Copyright Valley News. May not be reprinted or used online without permission. Send requests to permission@vnews.com.

Valley News Staff Writer
Published: 12/16/2019 10:07:32 PM
Modified: 12/16/2019 10:07:27 PM

HANOVER — A group of researchers at Dartmouth College say their recent discovery of a gene that regulates iron absorption in plants could help address the problem of iron deficiency experienced by more than 2 billion people, especially women and children, around the world.

Because people get iron from plants — either directly by eating beans, grains, nuts and vegetables, or indirectly through animals that eat plants — increasing the amount of iron that plants take up from soil and store could help prevent iron deficiency, which can add risk to pregnancy, cause fatigue and difficulty focusing, and also lead to developmental delays in children.

“We’re hoping (to) get plants to do what they do naturally, but just do it a little better,” said Mary Lou Guerinot, a Dartmouth professor of biological sciences who is the senior researcher for the project.

Guerinot and her team this month published their discovery of the gene URI, which regulates a carrier protein responsible for iron uptake that the team previously identified. URI is always present in the small, flowering plant Arabidopsis thaliana but is switched on in low-iron environments, triggering a cascade that causes the plant to take up more iron, the team found.

The discovery of this gene, published in the Proceedings of the National Academy of Sciences, was “very satisfying,” Guerinot said, noting that her team had some competition from other researchers to be the first to identify URI and describe how it works.

“We’re pretty excited,” said Guerinot, who holds a bachelor’s degree from Cornell University and a doctorate from Dalhousie University in Halifax, Nova Scotia. She served as a postdoctoral fellow at the University of Maryland and Michigan State University before coming to Dartmouth in 1985.

The finding also was greeted with enthusiasm by others in the field. 

“This work uncovered not only a new gene in the regulation of the iron deficiency response, but with it, an elegant mechanism illuminating how plants are capable of precisely orchestrating iron uptake and iron management,” Wolfgang Busch, a professor of plant molecular and cellular biology at the Salk Institute for Biological Studies in La Jolla, Calif., said via email. Busch was not involved in the Dartmouth study.

Guerinot’s team found that URI controls as many as 1,500 other genes in the plant, some of which are unrelated to iron absorption.

When there is enough iron in the soil, URI also controls a protein that halts the movement of iron from the soil into the plant’s root system, the researchers found.

This finding is the latest in the researchers’ decades-long investigation into the subject of how plants absorb iron, a highly competitive process, said Jeanne Harris, a University of Vermont plant biologist who was not involved in the study.

“Those who get it live. … Those who don’t lose,” Harris said.

The Dartmouth researchers’ finding, though not in a crop plant, can be applied to other plants such as those grown in low-iron environments, Harris said. The finding also could help to increase the amount of iron available to humans through plants, she said.

Though iron is condensed in red meat, many people do not have ready access to meat, Harris said.

“As we have more people on this Earth, (we) have to rely less and less on large animals,” she said.

While plants rely on iron for photosynthesis and growth, the metal can also be toxic to them. As a result, plants are “cautious” in their absorption of iron and turn off the uptake pathway quickly, Guerinot said.

If scientists can figure out how to turn on the iron uptake switch sooner and keep it on longer, they will be able to increase the amount of iron that plants absorb, which could help the plants themselves as well as the people who eat them, she said.

Down the road, Guerinot said this finding could help in the development of a gene editing process that could be used to develop commonly consumed crops such as rice and cassava with a higher iron content.

“We’re not done yet,” she said.

Valley News Staff Writer Nora Doyle-Burr can be reached at ndoyleburr@vnews.com or 603-727-3213.




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