RRC ID 30754
Author Kobayashi Y, Kobayashi Y, Watanabe T, Shaff JE, Ohta H, Kochian LV, Wagatsuma T, Kinraide TB, Koyama H.
Title Molecular and physiological analysis of Al³⁺ and H⁺ rhizotoxicities at moderately acidic conditions.
Journal Plant Physiol.
Abstract Al³⁺ and H⁺ toxicities predicted to occur at moderately acidic conditions (pH [water] = 5-5.5) in low-Ca soils were characterized by the combined approaches of computational modeling of electrostatic interactions of ions at the root plasma membrane (PM) surface and molecular/physiological analyses in Arabidopsis (Arabidopsis thaliana). Root growth inhibition in known hypersensitive mutants was correlated with computed {Al³⁺} at the PM surface ({Al³⁺}(PM)); inhibition was alleviated by increased Ca, which also reduced {Al³⁺}(PM) and correlated with cellular Al responses based on expression analysis of genes that are markers for Al stress. The Al-inducible Al tolerance genes ALUMINUM-ACTIVATED MALATE TRANSPORTER1 and ALUMINUM SENSITIVE3 were induced by levels of {Al³⁺}(PM) too low to inhibit root growth in tolerant genotypes, indicating that protective responses are triggered when {Al³⁺}(PM) was below levels that can initiate injury. Modeling of the H⁺ sensitivity of the SENSITIVE TO PROTON RHIZOTOXICITY1 knockout mutant identified a Ca alleviation mechanism of H⁺ rhizotoxicity, possibly involving stabilization of the cell wall. The phosphatidate phosphohydrolase1 (pah1) pah2 double mutant showed enhanced Al susceptibility under low-P conditions, where greater levels of negatively charged phospholipids in the PM occur, which increases {Al³⁺}(PM) through increased PM surface negativity compared with wild-type plants. Finally, we found that the nonalkalinizing Ca fertilizer gypsum improved the tolerance of the sensitive genotypes in moderately acidic soils. These findings fit our modeling predictions that root toxicity to Al³⁺ and H⁺ in moderately acidic soils involves interactions between both toxic ions in relation to Ca alleviation.
Volume 163(1)
Pages 180-92
Published 2013-9
DOI 10.1104/pp.113.222893
PII pp.113.222893
PMID 23839867
PMC PMC3762639
MeSH Aluminum / toxicity* Arabidopsis / growth & development Arabidopsis / physiology* Arabidopsis Proteins / genetics Calcium / pharmacology Cell Membrane / metabolism Gene Knockout Techniques Hydrogen / toxicity* Hydrogen-Ion Concentration Models, Genetic Plant Roots / growth & development Plant Roots / physiology Soil / chemistry Stress, Physiological
IF 6.305
Times Cited 18
Arabidopsis / Cultured plant cells, genes sja05800