Unraveling the contribution of NADP-malic enzyme 1 to aluminum stress response in Arabidopsis roots

GERRARD WHEELER, M. C.; ANDREO, C. S.; BADIA, M. B.; DRINCOVICH, M. F.

Córdoba

Congreso; LII Reunión Anual SAIB; 2016

SAIB

Malate plays a fundamental role in plant aluminum tolerance since its Al-binding capacity. In this work we analyze the participation of Arabidopsis thaliana NADP-malic enzyme 1 (NADP-ME1) in root malate metabolism and Al response. Arabidopsis insertional mutant plants lacking NADP-ME1 showed enhanced tolerance to Al, evidenced by a lower inhibition of root elongation compared to wild type, in presence of toxic Al concentrations. Additionally, qRT-PCR analysis showed a decreased expression of NADP-ME1 gene in wild type seedlings after 3 hours of Al treatment. The malate levels in roots and exudates after short Al treatments were similar in nadp-me1 compared to wt, although a significant increase of intracellular malate was observed after a long exposure to Al only in the knock-out line. The H2O2 content and the transcript levels of several Al tolerance related genes were analyzed in both plant types exposed to Al, as well as the response to glutamate, amino acid implicated in Al stress signal transduction. The results suggested that NADP-ME1 could be involved in regulating the levels of malate in the cytosol of the root apex and its loss may result in an increase in the content of this organic acid. Furthermore, this isoform may be affecting the signal transduction processes which lead to root growth inhibition, such as the generation of ROS or other signaling molecules.