Maris Nuhkat

Maris Nuhkat
University of Tartu · Institute of Technology

Master of Science

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26
Publications
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632
Citations

Publications

Publications (26)
Article
Full-text available
Plant stress signalling involves bursts of reactive oxygen species (ROS), which can be mimicked by the application of acute pulses of ozone (O3). Such O3‐pulses inhibit photosynthesis and trigger stomatal closure in a few minutes, but the signalling that underlies these responses remains largely unknown. We measured changes in Arabidopsis thaliana...
Article
Initiation of stomatal closure by various stimuli requires activation of guard cell plasma membrane anion channels, which are defined as rapid (R)- and slow (S)-type. The single-gene loss-of-function mutants of these proteins are well characterized. However, the impact of suppressing both the S- and R-type channels has not been studied. Here, by ge...
Article
Low concentrations of CO2 cause stomatal opening, whereas [CO2] elevation leads to stomatal closure. Classical studies have suggested a role for Ca²⁺ and protein phosphorylation in CO2-induced stomatal closing. Calcium-dependent protein kinases (CPKs) and calcineurin-B-like proteins (CBLs) can sense and translate cytosolic elevation of the second m...
Preprint
Full-text available
Guard cells regulate plant gas exchange by controlling the aperture of stomatal pores. Stomatal closure involves a multi-input signaling network that governs the activity of ion channels, which in turn regulate guard cell turgor pressure and volume. We describe a forward genetic screen to identify novel components involved in stomatal movements. Th...
Article
Full-text available
During drought, abscisic acid (ABA) induces closure of stomata via a signaling pathway that involves the Ca2+‐independent protein kinase OST1, as well as Ca2+‐dependent protein kinases (CPKs). However, the interconnection between OST1 and Ca2+ signaling in ABA‐induced stomatal closure has not been fully resolved. ABA‐induced Ca2+ signals were monit...
Article
Full-text available
Plants grow and reproduce within a highly dynamic environment that can see abrupt changes in conditions, such as light intensity, temperature, humidity, or interactions with biotic agents. Recent studies revealed that plants can respond within seconds to some of these conditions, engaging many different metabolic and molecular networks, as well as...
Article
Full-text available
Author Summary Human activities have increased the concentrations of CO2 and harmful air pollutants such as ozone in the troposphere. These changes can have detrimental consequences for agricultural productivity. Guard cells, which form stomatal pores on leaves, regulate plant gas exchange. To maintain photosynthesis, stomata open to allow CO2 upta...
Data
MPK12 interacts with HT1 and IBR5. Split-ubiquitin yeast two-hybrid assays with MPK12 and different versions of MPK12 with amino acid substitutions; MPK12 G53R with the same point mutation as in Cvi-0, MPK12 K70R kinase inactive version, MPK12 Y122C and MPK12 D196G, E200A constitutively active kinase versions. (A) Yeast growth observed on SD-leu-tr...
Data
RT-PCR analysis of full length MPK12 transcript in Col-0, mpk12-3, and mpk12-4 plants. ACTIN2 was amplified as a control. (TIF)
Data
Stable expression of YFP-labelled MPK12 in intact leaves of Arabidopsis thaliana and transient expression in leaves of Nicotiana benthamiana. Expression of MPK12-YFP (A) and MPK12 G53R-YFP (B) under native MPK12 promoter in A. thaliana Col-0. Transient expression under the CaMV35S promoter was also shown for MPK12-YFP (C) and MPK12 G53R-YFP in N. b...
Data
Identification of Col-S2 and cis mutation. (A) Ion leakage after 6 h of ozone exposure (350 ppb ozone). Experiment was repeated three times (mean ± SD; 1-way ANOVA of ozone treated plants). (B) Scheme of mapping the ozone sensitive trait of Col-S2. (C) CO2-induced changes in stomatal conductance in cas mutants (mean ± SEM; n = 5–6 plants). (D) Mapp...
Data
Stomatal index, length, and density in mpk12. (A) Stomatal index of studied lines (mean ± SEM; 1-way ANOVA, Tukey HSD post hoc test). Experiment was repeated twice (n = 81–84 plants). (B) Stomatal complex length of mpk12 lines (mean ± SEM; 1-way ANOVA). Sample size was 4–6 plants, altogether 84–126 stomatal complexes per line were measured. (C) Sto...
Data
Mutations in MPK12 are causing impaired CO2-responses in both cas-2 and gdsl3-1 mutants. (A) The originally described T-DNA insertions were confirmed in cas-2 and gdsl3-1 (GABI_492D11) plants by genotyping analyses. PCR product for the CAS gene was amplified by primers CASLP and CASRP. PCR product for the cas-2 insert was amplified by primers CASRP...
Data
Time-dependent changes in stomatal conductance. Various stimuli were applied as indicated by the bars or arrows in the legends of each panel. Stomatal opening induced by 100 ppm CO2 (A) and 50 μmol m-2s-1 blue light (B). ABA inhibited light-induced stomatal opening (C). Stomatal closure in response to darkness (D), 800 ppm CO2 (E), decrease in air...
Data
Deletion of MPK12 did not affect ABA-induced stomatal closure. The stomata in the MPK12 deletion mutant mpk12-4 closed after treatment with 10 μM ABA for 30 min, similar as in wild type. Data are average of 3 experiments, 10 stomata per experiment and condition. Small letters denote statistically significant differences according to 2-way ANOVA wit...
Data
MPK11 does not inhibit the activity of HT1. MPK11, an MPK from the same group as MPK12, was not able to inhibit HT1 showing that not all the Arabidopsis MPKs are inhibitors of HT1. This experiment was repeated four times. (TIF)
Data
Primers used in this study. (DOCX)
Data
Raw data for all figures and supplemental figures. (XLSX)
Data
A time course of Col-0, Cvi-0, Col-S and Cvi-T exposed to 350 ppb ozone. (WMV)
Article
Activation of the guard cell S-type anion channel SLAC1 is important for stomatal closure in response to diverse stimuli, including elevated CO2. The majority of known SLAC1 activation mechanisms depend on abscisic acid (ABA) signaling. Several lines of evidence point to a parallel ABA-independent mechanism of CO2-induced stomatal regulation; howev...
Preprint
Full-text available
Plant gas exchange is regulated by guard cells that form stomatal pores. Stomatal adjustments are crucial for plant survival; they regulate uptake of CO 2 for photosynthesis, loss of water and entrance of air pollutants such as ozone. We mapped ozone hypersensitivity, more open stomata and stomatal CO 2 -insensitivity phenotypes of the Arabidopsis...
Data
Movie S1 Movie of stomatal closure induced by nanoinfusion of 20 nM flg22.
Data
Fig. S1 Sensitivity of platinum‐iridium disc electrode to H2O2 production by mesophyll tissue. Fig. S2 Time‐dependent stomatal movement induced by nanoinfusion of control solution, 10 μM ABA, or 20 nM flg22 in selected accessions and mutants.
Article
Full-text available
During infection plants recognize microbe-associated molecular patterns (MAMPs), and this leads to stomatal closure. This study analyzes the molecular mechanisms underlying this MAMP response and its interrelation with ABA signaling. Stomata in intact Arabidopsis thaliana plants were stimulated with the bacterial MAMP flg22, or the stress hormone A...
Article
Contents 'Summary'I.II.III.IV.V. ReferencesSummaryStomata are an attractive experimental system in plant biology, because the responses of guard cells to environmental signals can be directly linked to changes in the aperture of stomatal pores. In this review, the mechanics of stomatal movement are discussed in relation to ion transport in guard ce...

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