NOVEL MECHANISM OF ALUMINUM TOXICITY RELATED TO SUGAR METABOLISM

Abstract

Aluminum ion is a major factor to limit crop productivity in acidic soils.  Aluminum ion accumulates on root apices, which immediately leads to the inhibition of cell elongation (namely, the inhibition of root elongation).  In addition, the enhancement of  reactive oxygen species (ROS)  production is commonly observed  in roots under  aluminum stress.   These symptoms are also observed in actively growing cells in culture.   The elucidation of the mechanisms of aluminum toxicity is necessary to find out effective strategies to overcome aluminum stress.  For this purpose, we investigated the responses to aluminum in cultured cell system as well as root system of tobacco, focusing on sugar metabolism.  We found that  aluminum ion immediately  inhibits sugar uptake,  which seems to be a mechanism whereby aluminum ion inhibits water uptake (namely, the  inhibition of cell elongation). The pathway from the  inhibition of sugar uptake till ROS production in the cells under aluminum stress should be elucidated in the future.