Potassium transporter KUP9 participates in K distribution in roots and leaves under low K stress.

Potassium (K) is a major essential element in plant cells, and KUP/HAK/KT-type K transporters participate in the absorption of K into roots and in the long-distance transport to above-ground parts. In Arabidopsis thaliana, KUP9 is involved in the transport of K and Cs in roots. In this study, we investigated KUP9 function in relation to the K status of the plant.

The HKT1 Na transporter protects plant fertility by decreasing Na content in stamen filaments.

Salinity stress can greatly reduce seed production because plants are especially sensitive to salt during their reproductive stage. Here, we show that the sodium ion transporter AtHKT1;1 is specifically expressed around the phloem and xylem of the stamen in to prevent a marked decrease in seed production caused by salt stress. The stamens of AtHKT1;1 mutant under salt stress overaccumulate Na, limiting their elongation and resulting in male sterility.

Green Tea Catechins, (-)-Catechin Gallate, and (-)-Gallocatechin Gallate are Potent Inhibitors of ABA-Induced Stomatal Closure.

Stomatal movement is indispensable for plant growth and survival in response to environmental stimuli. Cytosolic Ca elevation plays a crucial role in ABA-induced stomatal closure during drought stress; however, to what extent the Ca movement across the plasma membrane from the apoplast to the cytosol contributes to this process still needs clarification. Here the authors identify (-)-catechin gallate (CG) and (-)-gallocatechin gallate (GCG), components of green tea, as inhibitors of voltage-dependent K channels which regulate K fluxes in Arabidopsis thaliana guard cells.

Rice amino acid transporter-like 6 (OsATL6) is involved in amino acid homeostasis by modulating the vacuolar storage of glutamine in roots.

Glutamine is a product of ammonium (NH ) assimilation catalyzed by glutamine synthetase (GS) and glutamate synthase (GOGAT). The growth of NH -preferring paddy rice (Oryza sativa L.) depends on root NH assimilation and the subsequent root-to-shoot allocation of glutamine; however, little is known about the mechanism of glutamine storage in roots.

Calcium-Regulated Phosphorylation Systems Controlling Uptake and Balance of Plant Nutrients.

Essential elements taken up from the soil and distributed throughout the whole plant play diverse roles in different tissues. Cations and anions contribute to maintenance of intracellular osmolarity and the formation of membrane potential, while nitrate, ammonium, and sulfate are incorporated into amino acids and other organic compounds. In contrast to these ion species, calcium concentrations are usually kept low in the cytosol and calcium displays unique behavior as a cytosolic signaling molecule.

Guard Cell Membrane Anion Transport Systems and Their Regulatory Components: An Elaborate Mechanism Controlling Stress-Induced Stomatal Closure.

When plants are exposed to drastic environmental changes such as drought, salt or bacterial invasion, rapid stomatal movement confers tolerance to these stresses. This process involves a variety of guard cell expressed ion channels and their complex regulation network. Inward K⁺ channels mainly function in stomatal opening.

Cesium Inhibits Plant Growth Primarily Through Reduction of Potassium Influx and Accumulation in Arabidopsis.

Cesium (Cs+) is known to compete with the macronutrient potassium (K+) inside and outside of plants and to inhibit plant growth at high concentrations. However, the detailed molecular mechanisms of how Cs+ exerts its deleterious effects on K+ accumulation in plants are not fully elucidated. Here, we show that mutation in a member of the major K+ channel AKT1-KC1 complex renders Arabidopsis thaliana hypersensitive to Cs+.

N-myristoylation and S-acylation are common modifications of Ca -regulated Arabidopsis kinases and are required for activation of the SLAC1 anion channel.

N-myristoylation and S-acylation promote protein membrane association, allowing regulation of membrane proteins. However, how widespread this targeting mechanism is in plant signaling processes remains unknown. Through bioinformatics analyses, we determined that among plant protein kinase families, the occurrence of motifs indicative for dual lipidation by N-myristoylation and S-acylation is restricted to only five kinase families, including the Ca -regulated CDPK-SnRK and CBL protein families.

Identification of regions responsible for the function of the plant K channels KAT1 and AKT2 in Saccharomyces cerevisiae and Xenopus laevis oocytes.

The Arabidopsis K channel KAT1 complements in K-limited medium the growth of the K uptake defective Saccharomyces cerevisiae mutant strain CY162, while another K channel, AKT2, does not. To gain insight into the structural basis for this difference, we constructed 12 recombinant chimeric channels from these two genes. When expressed in CY162, only three of these chimeras fully rescued the growth of CY162 under K-limited conditions.