Submitted to: American Society of Plant Biologists Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: February 2, 2002
Publication Date: March 25, 2002
Citation: Mason, P.A., Garvin, D.F., Kochian, L.V. 2002. Anion channels and aluminum tolerance: the cellular and molecular analysis of clc anion channels from triticum aestivum. American Society of Plant Biologists Annual Meeting. 14:35. Technical Abstract: Aluminum (Al) toxicity is a primary limitation to agricultural productivity on acid soils, and is manifested primarily through an inhibition of root growth. Considerable evidence in the literature has accumulated associating Al tolerance with Al-induced exudation of organic acids from the root apex of tolerant genotypes. In Al tolerant wheat (Triticum aestivum), Al exposure triggers malate exudation from the root tip. The released malate is thought to chelate free Al3+ ions in the rhizosphere, thus preventing the entry of Al into the root tip (the site of Al toxicity). Tolerant cultivars of wheat also exhibit reduced aluminum accumulation in the root apex, supporting this concept of Al exclusion as a tolerance mechanism. Findings from ours and other labs have implicated plasma membrane anion channels as the primary transporter facilitating the organic acid exudation. To investigate this function, 8 members of the CLC anion channel family from wheat were cloned using a hybridization-based screen. The possible roles of these genes in Al tolerance are being characterized using molecular and cellular approaches. Southern mapping using ditelosomic lines has precluded the co-localization of these genes with previously identified genetic loci controlling Al tolerance. RNA expression studies indicate there is a significant variation in tissue specificity among these genes. GFP-CLC constructs are being generated to assay subcellular localization of the CLC protein. Finally, expression studies utilizing heterologous systems are being conducted to begin to elucidate the biophysical transport properties of these channels. Supported by USDA-NRI Competitive Grant #01-35301-10647 to LVK.