Loss of function of NADP-malic enzyme 1 results in lower sensitivity to aluminium

BADIA, MARIANA; MARIEL GERRARD WHEELER; ANDREO, CARLOS S; MARIA FABIANA DRINCOVICH

Congreso; XII Panamerican Association for Biochemistry and Molecular Biology (PABMB) Congress; 2013

In acidic soils, aluminum (Al) toxic species are solubilized causing root growth inhibition. The release of organic acids that chelate these ions plays a central role in plant Al tolerance. In A. thaliana, malate is the organic acid excreted to a greater extent. It has been demonstrated the importance of malate channels in this mechanism, but little is known about the metabolic changes underlying excretion. To determine if malic enzyme (ME), which catalyzes the oxidative decarboxylation of malate might be involved in this process, Arabidopsis mutant lines of each gene of the ME family were analyzed in response to Al. Plants lacking NADP-ME1 presented lower inhibition of root elongation and an increase in root malate levels after Al treatment. This increased tolerance was not seen in mutants of the other isoforms and could be related to the particular and confined localization of this protein in roots. Moreover, quantification of transcript levels showed a specific decrease in the expression of nadp-me1 in wild type seedlings exposed to Al. Thus, NADP-ME1 could be involved in regulating the levels of malate in the cytosol of the root apex and it loss may result in an increase in the content of this organic acid being available for excretion. Additionally, this isoform may be affecting the levels of signaling molecules of Al stress such as ROS or aminoacids