"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.
|Contact: Iqbal Pittalwala|
University of California - Riverside