Aluminum tolerance fix could open arable land

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 it expresses – play a major role in allowing rice to tolerate the toxic metal in acid soils.

Of all the cereal crops, rice is the most aluminum tolerant. In acidic soils, a form of aluminum, the Al3+ ion, is very toxic to plant roots and greatly reduces crop yields. Meanwhile, scientists race to feed the world's growing populations while arable lands become scarcer.

In a study published in the Proceedings of the National Academies of Sciences April 11, the researchers explain how the so-called NRAT1 gene in rice expresses a transport protein to move aluminum away from the root cell walls where it creates problems and into the cell, where it is sequestered in a vacuole, where it can't do any damage.

"This research opens the door for using NRAT1 to improve aluminum tolerance in other cereal crops," said Leon Kochian, a senior author of the paper and Cornell adjunct professor of plant biology and director of the U.S. Department of Agriculture's (USDA) Robert W. Holley Center for Agriculture and Health at Cornell.

The researchers, including Cornell rice geneticist Susan McCouch who co-directs this project with Kochian, had previously targeted the NRAT1 gene based on work done in McCouch's lab to genetically map aluminum tolerance using diverse lines of rice. In this paper, they sequenced the NRAT1 gene from 24 genetically diverse rice lines that were either aluminum-tolerant or sensitive. Based on the resulting DNA sequences, they identified aluminum tolerant- and aluminum-sensitive versions of the NRAT1 gene.