Location: Plant, Soil and Nutrition Research
Title: Aluminum-activated citrate and malate transporters encoded by distinct Al tolerance genes function independently in Arabidopsis Authors
Submitted to: Plant and Animal Genome Conference
Publication Type: Abstract Only
Publication Acceptance Date: January 3, 2008
Publication Date: January 16, 2008
Citation: Liu, J., Magalhaes, J., Shaff, J., Kochian, L.V. 2008. Aluminum-activated citrate and malate transporters encoded by distinct Al tolerance genes function independently in Arabidopsis. Plant and Animal Genome Conference. Technical Abstract: Aluminum (Al) -activated malate and citrate exudation from roots plays an important role in conferring Al tolerance to many plant species. Here, we report on the identification and characterization of AtMATE, the gene encoding an Al-activated root citrate efflux transporter that functions in Arabidopsis Al tolerance. Together with the previously characterized Al tolerance gene, AtALMT1, that encodes an Al-activated malate transporter, this discovery allows us to examine the relationship and interactions between these two organic acid transport systems in Arabidopsis. AtMATE is expressed in the root and its expression is induced by Al stress. A T-DNA insertion in the promoter of AtMATE sharply reduces the levels of AtMATE transcript, abolishes the inducibility of AtMATE gene expression as well as the Al-activated citrate exudation under Al stress. The AtALMT1::AtMATE double mutant lacks both Al-activated malate and citrate exudation from roots and this mutant is extremely hypersensitive to Al stress. The expression patterns of AtALMT1 and AtMATE and the profiles of the Al-activated malate and citrate exudation are not affected by the presence or absence of the other gene or the other organic acid exudation process, indicating that the AtALMT1-mediated Al-activated malate exudation, and the AtMATE-mediated Al-activated citrate exudation evolved and function independently of each other in conferring Al tolerance to plants.