Biochemists devise method for bypassing aluminum toxicity effects in plants

Oct 02, 2008
Biochemists devise method for bypassing aluminum toxicity effects in plants
Paul Larsen, an associate professor of biochemistry at UC Riverside, examines an Arabidopsis plant. Photo: UCR Strategic Communications

(PhysOrg.com) -- Aluminum toxicity, a global agricultural problem, halts root growth in plants, severely limiting agricultural productivity for more than half of the world's arable land.

For many years, scientists have puzzled over how toxic levels of aluminum damage the growing root. The popular understanding is that aluminum binds to several targets in the root system, blocking cell division, damaging DNA, and ultimately interrupting plant growth.

Now, working on the model plant Arabidopsis, a team of UC Riverside biochemists has determined that it is not aluminum toxicity that is directly responsible for inhibiting plant growth. The researchers identified a factor in plant cells, called AtATR, that functions as a built-in DNA surveillance system for alerting the plant of damage from excess aluminum and shutting down growth.

The researchers' experiments showed that AtATR can be manipulated to greatly enhance aluminum tolerance, resulting in plants whose roots can grow normally in soils that contain toxic levels of aluminum.

Study results appear in the Oct. 14 issue of Current Biology.

"Plants actively monitor aluminum-dependent damage through AtATR," said Paul Larsen, an associate professor of biochemistry and the lead author of the study. "But by breaking this assessment mechanism in a plant growing in soil with high aluminum content, we were able to stimulate plant growth again because the plant was no longer able to sense the damage aluminum caused. In other words, by bypassing this growth checkpoint, plants are not able to sense the effects of aluminum; they continue to grow even in an aluminum-toxic environment that is highly inhibitory to a normal Arabidopsis plant."

The research, which gives scientists new insights into how aluminum tolerance works in plants, offers a new strategy for engineering crop plants that can tolerate growth in aluminum-toxic environments, increasing crop production in areas that otherwise could not sustain agriculture.

"Dr. Larsen's work is a significant breakthrough in our understanding of how aluminum toxicity inhibits root growth," said Leon Kochian, a professor of plant biology at Cornell University, who was not involved in the research. "What he has shown, using an elegant combination of genetics, molecular biology and physiology, is that aluminum causes DNA damage in the growing root tip. The cells of this region have a mechanism to monitor this damage and shut down cell division and thus, root growth."

Larsen explained that a root tip has a "quiescent center" that houses stem cells – master cells, maintained throughout the life of the root, that develop into cell types and tissues. Aluminum toxicity results in the loss of these stem cells, and consequently cell division, bringing growth to a halt.

"Knocking off AtATR's functioning maintains the quiescent center," said Larsen, who joined UCR's Department of Biochemistry in 2000. "In our study, we broke AtATR throughout the plant. But if we can break this factor only in the root tip, the plant will not sense aluminum's damage to the root. The root then continues to grow and we regain productivity."

The researchers' experiments involved introducing random mutations throughout the genome of Arabidopsis and screening for those roots that can grow in the presence of high levels of aluminum.

A silvery-white metal, aluminum is the most abundant metallic element in the Earth's crust. Never found in the metallic form in nature, it occurs instead in compounds.

Next, Larsen's lab will work on identifying other factors in plants that detect DNA damage. His lab also plans to induce the AtATR mutation into crop plants such as tomato and corn to increase their aluminum tolerance.

Provided by University of California - Riverside

Explore further: How can we avoid kelp beds turning into barren grounds?

add to favorites email to friend print save as pdf

Related Stories

Aluminum tolerance fix could open arable land

Apr 30, 2014

(Phys.org) —With as much as 40 percent of the world's potentially arable land unusable due to aluminum toxicity, a solution may be near: Cornell agricultural scientists report that a gene – and the protein ...

Breeder works to reduce aluminum toxicity in rice

May 08, 2012

(Phys.org) -- As rice farmers around the world begin to turn from wet paddies to dry fields in an attempt to conserve water and mitigate climate change, they are facing a new foe: aluminum.

Planet Earth's playhouse

Dec 13, 2010

At Biosphere 2, scientists can move things around, control the climate, turn off certain parameters and run others full tilt.

Recommended for you

Male sex organ distinguishes 30 millipede species

16 minutes ago

The unique shapes of male sex organs have helped describe thirty new millipede species from the Great Western Woodlands in the Goldfields, the largest area of relatively undisturbed Mediterranean climate ...

How can we avoid kelp beds turning into barren grounds?

4 hours ago

Urchins are marine invertebrates that mould the biological richness of marine grounds. However, an excessive proliferation of urchins may also have severe ecological consequences on marine grounds as they ...

Genomes of malaria-carrying mosquitoes sequenced

19 hours ago

Nora Besansky, O'Hara Professor of Biological Sciences at the University of Notre Dame and a member of the University's Eck Institute for Global Health, has led an international team of scientists in sequencing ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

codesuidae
not rated yet Oct 02, 2008
So what are the consequences of disabling this safety mechanism? It sounds as if the root continues to grow in spite of DNA damage caused by the high levels of aluminum. Does this have consequences?
Rick69
not rated yet Oct 03, 2008
Unfortunately, this advancement will probably meet with a great deal of resistance because so much of the world is highly biased against genetically modified organisms.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.