Variation In Cereal Aluminum Tolerance Is Due To Transcriptional and Post-Transcriptional Regulation Of Cereal Aluminum Tolerance Genes

Plants have evolved different mechanisms for dealing with toxic metals in the environment, and these can involve avoidance (exclusion from a plant tissue/organ) or true tolerance (sequestration in an internal compartment). The best characterized metal resistance mechanisms involve crop adaptation to aluminum (Al) toxicity, which is a worldwide problem that arises in acid soils (pH <5). In these soils toxic forms of Al (primarily Al³⁺) are solubilized into the soil solution, damaging roots and resulting in reduced water and nutrient uptake. Because of the agronomic importance of Al toxicity, research on the identification of crop Al resistance genes has attracted significant interest from a number of laboratories around the world. This talk will focus on a well-documented Al resistance mechanism based on Al activation of specialized transporters localized in the root tip that release organic acids into the rhizosphere, where they chelate and prevent Al from entering the root. Our group has identified and characterized the major sorghum Al resistance gene/protein, SbMATE, which encodes a root apical plasma membrane MATE transporter that mediates Al-activated citrate efflux into the rhizosphere. In this talk we will discuss how regulation of SbMATE gene expression as well as regulation of SbMATE transport function underlies differential Al resistance in sorghum.