Scientists Find Evidence of a Common Genetic Key to Aluminum Tolerance in Plants

Millions of acres of nonproductive land may someday be transformed into amber waves of grain based on new genetic research by Agricultural Research Service scientists.

That's because the scientists have found a gene in barley that makes plants more able to withstand aluminum. A major component of soil clay, aluminum is the third most abundant element in the Earth's crust. At neutral or alkaline pH, it's not a problem for plants. However, in acid soils, the main form of aluminum is highly toxic to plants.

Aluminum toxicity can limit crop production on acid soils that cover well over half the world's 8 billion acres of potentially arable land, including about 86 million acres in the United States. When soils become acid, the toxic aluminum damages plant root systems, greatly reducing yields on these soils.

One approach to reducing aluminum toxicity is to develop crop varieties with increased genetic resistance to aluminum. ARS plant molecular biologist David F. Garvin--working with plant physiologist Leon V. Kochian at the U.S. Plant, Soil and Nutrition Laboratory in Ithaca, N.Y.--identified genetic markers for a single gene in barley that enhances aluminum tolerance. These markers can be used in breeding programs to rapidly shuttle aluminum tolerance genes from aluminum-tolerant barley varieties to aluminum-sensitive ones.

Furthermore, the results of their study suggest that aluminum tolerance in barley and its close relative, wheat, is due to the action of different forms of the same gene. Since wheat possesses superior aluminum tolerance to barley, it may be possible to genetically engineer increased aluminum tolerance in barley by introducing a wheat aluminum tolerance gene.

This research could provide insights into how some important grain species--including wheat, corn and sorghum--can tolerate high levels of aluminum in acid soils. Their findings are published in the May-June 2000 issue of Crop Science. ARS is U.S. Department of Agriculture's chief research agency.

Scientific contact: David F. Garvin, ARS U.S. Plant, Soil and Nutrition Laboratory, Ithaca, N.Y., phone (607) 255-7308, fax (607) 255-1132, dfg3@cornell.edu.