Involvement of phosphatidylinositol metabolism in aluminum-induced malate secretion in Arabidopsis. (12th April 2019)

• Record Type: Journal Article
• Authors: Wu, Liujie; Sadhukhan, Ayan; Kobayashi, Yuriko; Ogo, Naohisa; Tokizawa, Mutsutomo; Agrahari, Raj Kishan; Ito, Hiroki; Iuchi, Satoshi; Kobayashi, Masatomo; Asai, Akira; Koyama, Hiroyuki
• Is Part Of: Journal of experimental botany. Volume 70:Number 12(2019)
• Page Start: 3329
• Page End: 3342
• Publication Date: 2019-04-12
• Subjects: Aluminum -- Arabidopsis -- AtALMT1 -- inhibitor -- malate transport -- pharmacological approach -- PI3K -- PI4K -- PLC; Botany -- Periodicals; Botany, Experimental -- Periodicals; Plant physiology -- Periodicals; 580
• DOI: 10.1093/jxb/erz179
• Languages: English
• ISSNs: 0022-0957

Abstract

Abstract: To identify the upstream signaling of aluminum-induced malate secretion through aluminum-activated malate transporter 1 (AtALMT1), a pharmacological assay using inhibitors of human signal transduction pathways was performed. Early aluminum-induced transcription of AtALMT1 and other aluminum-responsive genes was significantly suppressed by phosphatidylinositol 4-kinase (PI4K) and phospholipase C (PLC) inhibitors, indicating that the PI4K–PLC metabolic pathway activates early aluminum signaling. Inhibitors of phosphatidylinositol 3-kinase (PI3K) and PI4K reduced aluminum-activated malate transport by AtALMT1, suggesting that both the PI3K and PI4K metabolic pathways regulate this process. These results were validated using T-DNA insertion mutants of PI4K and PI3K -RNAi lines. A human protein kinase inhibitor, putatively inhibiting homologous calcineurin B-like protein-interacting protein kinase and/or Ca-dependent protein kinase in Arabidopsis, suppressed late-phase aluminum-induced expression of AtALMT1, which was concomitant with the induction of an AtALMT1 repressor, WRKY46, and suppression of an AtALMT1 activator, Calmodulin-binding transcription activator 2 ( CAMTA2 ). In addition, a human deubiquitinase inhibitor suppressed aluminum-activated malate transport, suggesting that deubiquitinases can regulate this process. We also found a reduction of aluminum-induced citrate secretion in tobacco by applying inhibitors of PI3K and PI4K. Taken together, our results indicated that phosphatidylinositol metabolism regulates organic acid secretion in plants under aluminum stress. Abstract : Phosphatidylinositol signals are involved in the early aluminum-inducible expression of several genes, including STOP1-regulated genes and aluminum-biomarker genes, and in malate transport by AtALMT1.