Low ABA concentration promotes root growth and hydrotropism through relief of ABA INSENSITIVE 1-mediated inhibition of plasma membrane H+-ATPase 2.
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ABSTRACT:
SUBMITTER: Miao R
PROVIDER: S-EPMC7968848 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Pattern recognition receptors (PRRs) at the plasma membrane promote plant immunity through the detection of conserved microbe-associated molecular patterns (MAMPs). In plants, the PRR for bacterial flagellin (flg22) is encoded by the receptor kinase FLS2. One of the earliest MAMP responses is the rapid and transient increase of cytosolic calcium (Ca2+) ions, which is required for many of the well-described downstream responses, e.g. generation of reactive oxygen species (ROS) and the transcriptional activation of defence-associated genes. Despite its relevance, the molecular components regulating the Ca2+ burst remain largely unknown. Here, we show that the plasma membrane P2B-type Ca2+ ATPase ACA8 forms a dynamic complex with the PRR FLS2. ACA8 and its closest homologue ACA10 are required for immunity against virulent bacteria. Mutant aca8 aca10 plants are reduced in the flg22-induced Ca2+ burst, show reduced ROS production and exhibit altered transcriptional reprogramming. In particular, flg22-induced gene expression is elevated downstream of signalling mitogen-activated protein (MAP) kinases, but reduced downstream of the calcium-dependent protein (CDP) kinase cascade. These results demonstrate that the fine regulation of Ca2+ fluxes in the cytosol is critical for the coordination of the downstream MAMP responses and provide for the first time a link between the FLS2 receptor complex and signalling kinases via the secondary messenger Ca2+. ACA8 also interacted with the BRI1 and CLV1 receptor kinases, which correlated with the developmental phenotypes of aca8 aca10 mutants suggesting a broader role for Ca2+ ATPases in receptor-mediated signalling. We used Affymetrix Arabidopsis Tiling 1.0R Array to compare global transcript levels in 7 days-old sterile grown seedlings. Steady-state mRNA levels in total RNA samples of 7 days old sterile seedlings
2012-04-24 | E-GEOD-31517 | biostudies-arrayexpress
Project description:Pattern recognition receptors (PRRs) at the plasma membrane promote plant immunity through the detection of conserved microbe-associated molecular patterns (MAMPs). In plants, the PRR for bacterial flagellin (flg22) is encoded by the receptor kinase FLS2. One of the earliest MAMP responses is the rapid and transient increase of cytosolic calcium (Ca2+) ions, which is required for many of the well-described downstream responses, e.g. generation of reactive oxygen species (ROS) and the transcriptional activation of defence-associated genes. Despite its relevance, the molecular components regulating the Ca2+ burst remain largely unknown. Here, we show that the plasma membrane P2B-type Ca2+ ATPase ACA8 forms a dynamic complex with the PRR FLS2. ACA8 and its closest homologue ACA10 are required for immunity against virulent bacteria. Mutant aca8 aca10 plants are reduced in the flg22-induced Ca2+ burst, show reduced ROS production and exhibit altered transcriptional reprogramming. In particular, flg22-induced gene expression is elevated downstream of signalling mitogen-activated protein (MAP) kinases, but reduced downstream of the calcium-dependent protein (CDP) kinase cascade. These results demonstrate that the fine regulation of Ca2+ fluxes in the cytosol is critical for the coordination of the downstream MAMP responses and provide for the first time a link between the FLS2 receptor complex and signalling kinases via the secondary messenger Ca2+. ACA8 also interacted with the BRI1 and CLV1 receptor kinases, which correlated with the developmental phenotypes of aca8 aca10 mutants suggesting a broader role for Ca2+ ATPases in receptor-mediated signalling. We used Affymetrix Arabidopsis Tiling 1.0R Array to compare global transcript levels in 7 days-old sterile grown seedlings.
2012-04-25 | GSE31517 | GEO
Project description:The phenomenon of plant root tips sensing moisture gradient in soil and growing towards higher water potential is designated as root hydrotropism, which is critical for plants to survive when water is a limited factor. Molecular mechanisms regulating such a fundamental process, however, are largely unknown. Here we report our identification that cytokinins are key signaling molecules directing root growth orientation in a hydrostimulation (moisture gradient) condition. Lower water potential side of the root tip shows more cytokinin response relative to the higher water potential side. Consequently, two cytokinin downstream type-A response regulators, ARR16 and ARR17, were found to be up-regulated at the lower water potential side, causing increased cell division in the meristem zone, which allows the root to bend towards higher water potential side. Genetic analyses indicated that various cytokinin biosynthesis and signaling mutants, including the arr16 arr17 double mutant, are significantly less responsive to hydrostimulation. Consistently, treatments with chemical inhibitors interfering with either cytokinin biosynthesis or cell division completely abolished root hydrotropic response. Asymmetrically induced expression of ARR16 or ARR17 effectively led to root bending in both wild-type and miz1, a previously known hydrotropism-defective mutant. These data demonstrate that asymmetric cytokinin distribution is a primary determinant governing root hydrotropism.
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Project description:Although the ability of humic (HA) and fulvic acids (FA) to improve plant growth has been demonstrated, knowledge about the mechanisms responsible for the direct effects of HA and FA on the promotion of plant growth is scarce and fragmentary. Our study investigated the causal role of both root PM H+-ATPase activity and ABA in the SHA-promoting action on both root and shoot growth. The involvement of these processes in the regulation of shoot cytokinin concentration and activity was also studied. Our aim was to integrate such plant responses for providing new insights to the current model on the mode of action of HA for promoting root and shoot growth. Experiments employing specific inhibitors and using Cucumis sativus L. plants show that both the root PM H+-ATPase activity and root ABA play a crucial role in the root growth-promoting action of SHA. With regard to the HA-promoting effects on shoot growth, two pathways of events triggered by the interaction of SHA with plant roots are essential for the increase in root PM H+-ATPase activity-which also mediates an increase in cytokinin concentration and action in the shoot-and the ABA-mediated increase in hydraulic conductivity (Lpr).
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Project description:In this work, we set out to identify and characterize the calcium occluded intermediate(s) of the plasma membrane Ca(2+)-ATPase (PMCA) to study the mechanism of calcium transport. To this end, we developed a procedure for measuring the occlusion of Ca(2+) in microsomes containing PMCA. This involves a system for overexpression of the PMCA and the use of a rapid mixing device combined with a filtration chamber, allowing the isolation of the enzyme and quantification of retained calcium. Measurements of retained calcium as a function of the Ca(2+) concentration in steady state showed a hyperbolic dependence with an apparent dissociation constant of 12 ± 2.2 ?M, which agrees with the value found through measurements of PMCA activity in the absence of calmodulin. When enzyme phosphorylation and the retained calcium were studied as a function of time in the presence of La(III) (inducing accumulation of phosphoenzyme in the E(1)P state), we obtained apparent rate constants not significantly different from each other. Quantification of EP and retained calcium in steady state yield a stoichiometry of one mole of occluded calcium per mole of phosphoenzyme. These results demonstrate for the first time that one calcium ion becomes occluded in the E(1)P-phosphorylated intermediate of the PMCA.
| S-EPMC3173191 | biostudies-literature
Project description:Plasma membrane (PM) H+-ATPase contributes to nutrient uptake and stomatal opening by creating proton gradient across the membrane. A dominant mutation in the OPEN STOMATA2 locus (OST2-2D) constitutively activates Arabidopsis PM H+-ATPase 1 (AHA1), enlarging proton motive force for root nutrient uptake. However, the stomatal opening is also constitutively enhanced in the ost2-2D, which results in drought hypersensitivity. Therefore, we postulated that the root-specific activation of OST2/AHA1 could be an ideal design for improving nutrient uptake efficiency without causing drought hypersensitivity. Accordingly, we grafted Col-0 (WT) scions onto rootstock originating from WT or ost2-2D and analyzed the vegetative growth, nutrient element content, and transcriptomes of the grafted plants grown under nutrient-rich or -poor conditions.
2022-06-22 | E-MTAB-11843 | biostudies-arrayexpress
Project description:How Ca2+-dependent signaling effectors are regulated in cardiomyocytes, given the extreme cytoplasmic Ca2+ concentration changes that underlie contraction, remains unknown. Cardiomyocyte plasma membrane Ca2+-ATPase (PMCA) extrudes Ca2+ but has little effect on excitation-contraction coupling, suggesting its potential role in controlling Ca2+-dependent signaling effectors such as calcineurin. We generated cardiac-specific inducible PMCA4b transgenic mice that displayed normal global Ca2+ transient and cellular contraction levels and reduced cardiac hypertrophy following transverse aortic constriction (TAC) or phenylephrine/Ang II infusion, but showed no reduction in exercise-induced hypertrophy. Transgenic mice were protected from decompensation and fibrosis following long-term TAC. The PMCA4b transgene reduced the hypertrophic augmentation associated with transient receptor potential canonical 3 channel overexpression, but not that associated with activated calcineurin. Furthermore, Pmca4 gene-targeted mice showed increased cardiac hypertrophy and heart failure events after TAC. Physical associations between PMCA4b and calcineurin were enhanced by TAC and by agonist stimulation of cultured neonatal cardiomyocytes. PMCA4b reduced calcineurin nuclear factor of activated T cell-luciferase activity after TAC and in cultured neonatal cardiomyocytes after agonist stimulation. PMCA4b overexpression inhibited cultured cardiomyocyte hypertrophy following agonist stimulation, but much less so in a Ca2+ pumping-deficient PMCA4b mutant. Thus, Pmca4b likely reduces the local Ca2+ signals involved in reactive cardiomyocyte hypertrophy via calcineurin regulation.
| S-EPMC2662553 | biostudies-literature
Project description:Glucose metabolism causes activation of the yeast plasma-membrane H+-ATPase. The molecular mechanism of this regulation is not known, but it is probably mediated by phosphorylation of the enzyme. The involvement in this process of several kinases has been suggested but their actual role has not been proved. The physiological role of a calmodulin-dependent protein kinase in glucose-induced activation was investigated by studying the effect of specific calmodulin antagonists on the glucose-induced ATPase kinetic changes in wild-type and two mutant strains affected in the glucose regulation of the enzyme. Preincubation of the cells with calmidazolium or compound 48/80 impeded the increase in ATPase activity by reducing the Vmax of the enzyme without modifying the apparent affinity for ATP in the three strains. In one mutant, pma1-T912A, the putative calmodulin-dependent protein kinase-phosphorylatable Thr-912 was eliminated, and in the other, pma1-P536L, H+-ATPase was constitutively activated, suggesting that the antagonistic effect was not mediated by a calmodulin-dependent protein kinase and not related to glucose regulation. This was corroborated when the in vitro effect of the calmodulin antagonists on H+-ATPase activity was tested. Purified plasma membranes from glucose-starved or glucose-fermenting cells from both pma1-P890X, another constitutively activated ATPase mutant, and wild-type strains were preincubated with calmidazolium or melittin. In all cases, ATP hydrolysis was inhibited with an IC50 of approximately 1 microM. This inhibition was reversed by calmodulin. Analysis of the calmodulin-binding protein pattern in the plasma-membrane fraction eliminates ATPase as the calmodulin target protein. We conclude that H+-ATPase inhibition by calmodulin antagonists is mediated by an as yet unidentified calmodulin-dependent membrane protein.
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Project description:The plant plasma membrane (PM) H+-ATPase regulates pH homeostasis and cell elongation in roots through the formation of an electrochemical H+ gradient across the PM and a decrease in apoplastic pH; however, the detailed signaling for the regulation of PM H+-ATPases remains unclear. Here, we show that an auxin influx carrier, AUXIN RESISTANT1 (AUX1), is required for the maintenance of PM H+-ATPase activity and proper root elongation. We isolated a low pH-hypersensitive 1 (loph1) mutant by a genetic screen of Arabidopsis thaliana on low pH agar plates. The loph1 mutant is a loss-of-function mutant of the AUX1 gene and exhibits a root growth retardation restricted to the low pH condition. The ATP hydrolysis and H+ extrusion activities of the PM H+-ATPase were reduced in loph1 roots. Furthermore, the phosphorylation of the penultimate threonine of the PM H+-ATPase was reduced in loph1 roots under both normal and low pH conditions without reduction of the amount of PM H+-ATPase. Expression of the DR5:GUS reporter gene and auxin-responsive genes suggested that endogenous auxin levels were lower in loph1 roots than in the wild type. The aux1-7 mutant roots also exhibited root growth retardation in the low pH condition like the loph1 roots. These results indicate that AUX1 positively regulates the PM H+-ATPase activity through maintenance of the auxin accumulation in root tips, and this process may serve to maintain root elongation especially under low pH conditions.
| S-EPMC5434668 | biostudies-literature
Project description:pH is an important factor regulating plant growth. Here, we found that rice was better adapted to low pH than alkaline conditions, as its growth was severely inhibited at high pH, with shorter root length and an extreme biomass reduction. Under alkaline stress, the expression of genes for ethylene biosynthesis enzymes in rice roots was strongly induced by high pH and exogenous ethylene precursor ACC and ethylene overproduction in etol1-1 mutant aggravated the alkaline stress-mediated inhibition of rice growth, especially for the root elongation with decreased cell length in root apical regions. Conversely, the ethylene perception antagonist silver (Ag+) and ein2-1 mutants could partly alleviate the alkaline-induced root elongation inhibition. The H+-ATPase activity was extremely inhibited by alkaline stress and exogenous ACC. However, the H+-ATPase-mediated rhizosphere acidification was enhanced by exogenous Ag+, while H+ efflux on the root surface was extremely inhibited by exogenous ACC, suggesting that ethylene negatively regulated H+-ATPase activity under high-pH stress. Our results demonstrate that H+-ATPase is involved in ethylene-mediated inhibition of rice growth under alkaline stress.
| S-EPMC5660857 | biostudies-literature