Mechanisms of Aluminum Tolerance in Wheat

Plants are not the biggest fans of aluminum, especially in acidic soils. Because of soil acidity, aluminum from minerals dissolves in the soil and gets converted to its toxic form: the Al³⁺ cation. Aluminum toxicity in acidic soils is a big problem in crop production in as much as half the world's arable land, mostly in developing countries have acidic soils. Aluminum toxicity has also been a big headache for Australian farmers. Approximately 50 percent of Australia's agricultural land has a surface pH of 5.5 or lower.

Researchers at the Australian Commonwealth Scientific and Research Organization (CSIRO) have identified two mechanisms for aluminum tolerance in wheat. The scientists found that some wheat plants secrete malate, an organic acid best known for giving tartness to fruits such as apple, in their root tips. Malate binds with the toxic metal to produce a stable compound that is harmless to plants. Other plants like wheat tolerate aluminum toxicity by producing citric acid. Citric acid binds aluminum ions very effectively, preventing the toxic metal from entering the roots. The CSIRO scientists have identified the genes responsible for these activities and are looking to include the trait in new wheat varieties.

The original article is available at http://www.csiro.au/files/files/pqn2.pdf