Analysis of the effect of permeant solutes on the hydraulic resistance of the plasma membrane in cells of Chara corallina.

In the cells of Chara corallina, permeant monohydric alcohols including methanol, ethanol and 1-propanol increased the hydraulic resistance of the membrane (Lp). We found that the relative value of the hydraulic resistance (Lp) was linearly dependent on the concentration (C) of the alcohol. The relationship is expressed in the equation: Lp = ρC + 1, where ρ is the hydraulic resistance modifier coefficient of the membrane.

In planta evidence that the HAK transporter OsHAK2 is involved in Na+ transport in rice.

HAK family transporters primarily function as K+ transporters and play major roles in K+ uptake and translocation in plants, whereas several HAK transporters exhibit Na+ transport activity. OsHAK2, a rice HAK transporter, was shown to mediate Na+ transport in Escherichia coli in a previous study. In this study, we investigated whether OsHAK2 is involved in Na+ transport in the rice plant.

Calcium control of the hydraulic resistance in cells of Chara corallina.

The hydraulic resistance (the reciprocal of the hydraulic conductivity Lp) Lp was measured in cells of Chara corallina by the method of transcellular osmosis. Treatment of cells with 100 mM KCl decreased Lp significantly. Subsequent treatment of the cells with 70 mM CaCl recovered the decreased Lp to the original value.

Distinct Functions of the Atypical Terminal Hydrophilic Domain of the HKT Transporter in the Liverwort Marchantia polymorpha.

K+/Na+ homeostasis is important for land plants, particularly under salt stress. In this study, the structure and ion transport properties of the high-affinity K+ transporter (HKT) of the liverwort Marchantia polymorpha were investigated. Only one HKT gene, MpHKT1, was identified in the genome of M.

Identification and Characterization of Rice Variants.

In rice, the high-affinity K transporter, , functions as a Na-selective transporter. mRNA variants of have been reported previously, but their functions remain unknown. In this study, five variants () were identified from japonica rice (Nipponbare) in addition to .

Physiological Role of Aerobic Fermentation Constitutively Expressed in an Aluminum-Tolerant Cell Line of Tobacco (Nicotiana tabacum).

Aluminum (Al)-tolerant tobacco cell line ALT301 derived from SL (wild-type) hardly exhibits Al-triggered reactive oxygen species (ROS) compared with SL. Molecular mechanism leading to this phenotype was investigated comparatively with SL. Under normal growth condition, metabolome data suggested the activation of glycolysis and lactate fermentation but the repression of the tricarboxylic acid (TCA) cycle in ALT301, namely aerobic fermentation, which seemed to be transcriptionally controlled partly by higher expression of genes encoding lactate dehydrogenase and pyruvate dehydrogenase kinase.

Greetings from the new Editor-in-Chief of the Journal of Plant Research 2021.

It is my pleasure to be writing this editorial as Editor-in-Chief of the Journal of Plant Research (JPR) for the next 4 years, following the former Editor-in-Chief, Prof. Kouki Hikosaka of Tohoku University. I will do my best to improve JPR along with all editors, board members, and readers.

Age dependence of the hydraulic resistances of the plasma membrane and the tonoplast (vacuolar membrane) in cells of Chara corallina.

Hydraulic resistances (reciprocals of hydraulic conductivities) of the cell (Lp), the cell wall (Lp), the membrane (Lp), the plasma membrane (Lp), and the tonoplast (Lp) were determined in individual internodal cells of Chara corallina and their dependence on the cell age was studied. The thickness of the cell wall (d) was adopted as an index of the cell age, since the cell wall of spring-grown young cells (sg-cells) was found to be significantly thinner than that of winter-spent old cells (ws-cells). Both Lp and Lp were found to increase with cell age.

Mechanisms Activating Latent Functions of PIP Aquaporin Water Channels via the Interaction between PIP1 and PIP2 Proteins.

Plant plasma membrane-type plasma membrane intrinsic protein (PIP) aquaporins are classified into two groups, PIP1s and PIP2s. In this study, we focused on HvPIP1;2, a PIP1 in barley (Hordeum vulgare), to dissect the molecular mechanisms that evoke HvPIP1-mediated water transport. No HvPIP1;2 protein was localized to the plasma membrane when expressed alone in Xenopus laevis oocytes.

A Survey of Barley PIP Aquaporin Ionic Conductance Reveals Ca-Sensitive Na and K Conductance.

Some plasma membrane intrinsic protein (PIP) aquaporins can facilitate ion transport. Here we report that one of the 12 barley PIPs (PIP1 and PIP2) tested, , facilitated cation transport when expressed in oocytes. -associated ion currents were detected with Na and K, but not Cs, Rb, or Li, and was inhibited by Ba, Ca, and Cd and to a lesser extent Mg, which also interacted with Ca.

Na Transporter SvHKT1;1 from a Halophytic Turf Grass Is Specifically Upregulated by High Na Concentration and Regulates Shoot Na Concentration.

We characterized an Na transporter SvHKT1;1 from a halophytic turf grass, . SvHKT1;1 mediated inward and outward Na transport in oocytes and did not complement K transporter-defective mutant yeast. SvHKT1;1 did not complement mutant , suggesting its distinguishable function from other typical HKT1 transporters.

Expression and Ion Transport Activity of Rice Variants.

in rice, belongs to the high-affinity K Transporter family, has been found to be involved in salt tolerance. in rice (Nipponbare) produces mRNA variants, but their functions remain elusive. In salt tolerant rice, Pokkali, eight variants (V1-V8) were identified in addition to the full-length (FL) cDNA.

Ectopic expression of a rice plasma membrane intrinsic protein (OsPIP1;3) promotes plant growth and water uptake.

Plasma membrane intrinsic proteins (PIPs) are known to be major facilitators of the movement of a number of substrates across cell membranes. From a drought-resistant cultivar of Oryza sativa (rice), we isolated an OsPIP1;3 gene single-nucleotide polymorphism (SNP) that is mostly expressed in rice roots and is strongly responsive to drought stress. Immunocytochemistry showed that OsPIP1;3 majorly accumulated on the proximal end of the endodermis and the cell surface around the xylem.

High-Affinity K+ Transporters from a Halophyte, Sporobolus virginicus, Mediate Both K+ and Na+ Transport in Transgenic Arabidopsis, X. laevis Oocytes and Yeast.

Class II high-affinity potassium transporters (HKTs) have been proposed to mediate Na+-K+ co-transport in plants, as well as Na+ and K+ homeostasis under K+-starved and saline environments. We identified class II HKTs, namely SvHKT2;1 and SvHKT2;2 (SvHKTs), from the halophytic turf grass, Sporobolus virginicus. SvHKT2;2 expression in S.

A Cyclic Nucleotide-Gated Channel, HvCNGC2-3, Is Activated by the Co-Presence of Na⁺ and K⁺ and Permeable to Na⁺ and K⁺ Non-Selectively.

Cyclic nucleotide-gated channels (CNGCs) have been postulated to contribute significantly in plant development and stress resistance. However, their electrophysiological properties remain poorly understood. Here, we characterized barley CNGC2-3 (HvCNGC2-3) by the two-electrode voltage-clamp technique in the oocyte heterologous expression system.

The mechanism of SO -induced stomatal closure differs from O and CO responses and is mediated by nonapoptotic cell death in guard cells.

Plants closing stomata in the presence of harmful gases is believed to be a stress avoidance mechanism. SO , one of the major airborne pollutants, has long been reported to induce stomatal closure, yet the mechanism remains unknown. Little is known about the stomatal response to airborne pollutants besides O .

T-DNA Tagging-Based Gain-of-Function of OsHKT1;4 Reinforces Na Exclusion from Leaves and Stems but Triggers Na Toxicity in Roots of Rice Under Salt Stress.

The high affinity K⁺ transporter 1;4 (HKT1;4) in rice (), which shows Na⁺ selective transport with little K⁺ transport activity, has been suggested to be involved in reducing Na in leaves and stems under salt stress. However, detailed physiological roles of OsHKT1;4 remain unknown. Here, we have characterized a transfer DNA (T-DNA) insertion mutant line of rice, which overexpresses ;, owing to enhancer elements in the T-DNA, to gain an insight into the impact of OsHKT1;4 on salt tolerance of rice.

Identification of an H O permeable PIP aquaporin in barley and a serine residue promoting H O transport.

A barley (Hordeum vulgare) plasma membrane type aquaporin, HvPIP2;5, was identified as an H O permeable aquaporin among 21 barley and rice PIPs examined in the heterologous expression system using Saccharomyces cerevisiae. Four TIPs were also detected as H O -transporting aquaporins among 15 barley and rice TIPs. Influx of H O into yeast cells expressing HvPIP2;5 was determined with a florescent-dye-based assay.

Exogenous application of abscisic acid (ABA) increases root and cell hydraulic conductivity and abundance of some aquaporin isoforms in the ABA-deficient barley mutant Az34.

Background and Aims Regulation of water channel aquaporins (AQPs) provides another mechanism by which abscisic acid (ABA) may influence water flow through plants. To the best of our knowledge, no studies have addressed the changes in ABA levels, the abundance of AQPs and root cell hydraulic conductivity (LpCell) in the same tissues. Thus, we followed the mechanisms by which ABA affects root hydraulics in an ABA-deficient barley mutant Az34 and its parental line 'Steptoe'.

Genome-Wide Characterization of Major Intrinsic Proteins in Four Grass Plants and Their Non-Aqua Transport Selectivity Profiles with Comparative Perspective.

Major intrinsic proteins (MIPs), commonly known as aquaporins, transport not only water in plants but also other substrates of physiological significance and heavy metals. In most of the higher plants, MIPs are divided into five subfamilies (PIPs, TIPs, NIPs, SIPs and XIPs). Herein, we identified 68, 42, 38 and 28 full-length MIPs, respectively in the genomes of four monocot grass plants, specifically Panicum virgatum, Setaria italica, Sorghum bicolor and Brachypodium distachyon.