Mikael Brosche

Mikael Brosche
University of Helsinki | HY · Department of Biosciences

PhD

About

159
Publications
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Publications

Publications (159)
Article
Programmed cell death is integral to plant life and required for stress responses, immunity, and development. Our understanding of the regulation of programmed cell death is incomplete, especially concerning regulators involved in multiple divergent processes. The botrytis-susceptible (bos1) mutant of Arabidopsis is highly susceptible to fungal inf...
Article
Full-text available
Plants live in a world of changing environments, where they are continuously challenged by alternating biotic and abiotic stresses. To transfer information from the environment to appropriate protective responses, plants use many different signaling molecules and pathways. Reactive oxygen species (ROS) are critical signaling molecules in the regula...
Article
Full-text available
Vaccinium darrowii is a subtropical wild blueberry species, which was used to breed economically important southern highbush cultivars. The adaptation traits of V. darrowii to subtropical climates would provide valuable information for breeding blueberry and perhaps other plants, especially against the background of global warming. Here, we assembl...
Preprint
Programmed cell death (PCD) is required for many aspects of plant biology, including stress responses, immunity, and plant development including root and flower development. Our understanding of PCD regulation is incomplete, especially concerning regulators involved in multiple divergent processes. The botrytis-suscetible1 (bos1) mutant is one of t...
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...
Preprint
Full-text available
Vaccinium darrowii is a subtropical wild blueberry species, which was used to breed economically important southern highbush cultivars. The adaptation traits of V. darrowii to subtropical climate would provide valuable information for breeding blueberry and perhaps other plants, especially against the background of global warming. Here, we assemble...
Article
Full-text available
Jasmonic acid (JA) and salicylic acid (SA) regulate stomatal closure, preventing pathogen invasion into plants. However, to which extent abscisic acid (ABA), SA, and JA interact and what the roles of SA and JA are in stomatal responses to environmental cues remains unclear. Here, by using intact plant gas-exchange measurements in JA and SA single a...
Article
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High levels of phenotypic variation in resistance appears to be nearly ubiquitous across natural host populations. Molecular processes contributing to this variation in nature are still poorly known, although theory predicts resistance to evolve at specific loci driven by pathogen-imposed selection. Nucleotide-binding leucine-rich repeat (NLR) gene...
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...
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Tropospheric ozone (O3) is a major air pollutant that decreases yield of important crops worldwide. Despite long-lasting research of its negative effects on plants, there are many gaps in our knowledge on how plants respond to O3. In this study, we used natural variation in the model plant Arabidopsis (Arabidopsis thaliana) to characterize molecula...
Article
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Plants require interaction between signaling pathways to differentiate and integrate stress responses and deploy appropriate defenses. The hormones ethylene, salicylic acid (SA), and jasmonic acid (JA) are important regulators of plant defenses. Numerous interactions between these signaling pathways are the cornerstone of robust plant immunity. Add...
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Trans-methylation reactions are intrinsic to cellular metabolism in all living organisms. In land plants, a range of substrate-specific methyltransferases catalyze the methylation of DNA, RNA, proteins, cell wall components and numerous species-specific metabolites, thereby providing means for growth and acclimation in various terrestrial habitats....
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Background and aims: The stomatal conductance (gs) of most plant species decreases in response to elevated atmospheric CO2 concentration. This response could have a significant impact on plant water use in a future climate. However, the regulation of the CO2-induced stomatal closure response is not fully understood. Moreover, the potential genetic...
Preprint
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The photoreceptors UV RESISTANCE LOCUS 8 (UVR8) and CRYPTOCHROMES 1 and 2 (CRYs) play major roles in the perception of UV-B (280–315 nm) and UV-A/blue radiation (315–500 nm), respectively. However, it is poorly understood how they function in sunlight. The roles of UVR8 and CRYs were assessed in a factorial experiment with Arabidopsis thaliana wild...
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Strigolactones are a group of phytohormones that control developmental processes including shoot branching and various plant–environment interactions in plants. We previously showed that the strigolactone perception mutant more axillary branches 2 (max2) has increased susceptibility to plant pathogenic bacteria. Here we show that both strigolactone...
Preprint
Full-text available
Trans-methylation reactions are intrinsic to cellular metabolism in all living organisms. In land plants, a range of substrate-specific methyltransferases catalyze the methylation of DNA, RNA, proteins, cell wall components and numerous species-specific metabolites, thereby providing means for growth and acclimation in various terrestrial habitats....
Article
Full-text available
Plants optimize their growth and survival through highly integrated regulatory networks that coordinate defensive measures and developmental transitions in response to environmental cues. Protein phosphatase 2A (PP2A) is a key signaling component that controls stress reactions and growth at different stages of plant development, and the PP2A regula...
Preprint
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To cope with vast amounts of data produced by metabolomic and mixture analysis using NMR, the employed analysis techniques and tools are very important. In this paper, we demonstrate quantitative 1 H and 2D-JRES NMR analysis of Arabidopsis thaliana extracts utilizing our ImatraNMR and SimpeleNMR software to automate the processing the spectra, extr...
Article
Prevailing evidence supports that ABA negatively influences immunity against the fungal pathogen, Botrytiscinerea (Botrytis), in most but not all cases. ABA is required for cuticle biosynthesis, and cuticle permeability enhances Botrytis immunity via unknown mechanisms. This complex web of responses obscures the role of ABA in Botrytis immunity. He...
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In the version of this article initially published, there was a mistake in the calculation of the nucleotide mutation rate per site per generation: 1 × 10⁻⁹ mutations per site per generation was used, whereas 9.5 × 10⁻⁹ was correct. This error affects the interpretation of population-size changes over time and their possible correspondence with kno...
Article
Full-text available
Cryptochromes (CRYs) and UV RESISTANCE LOCUS 8 (UVR8) photoreceptors perceive UV-A/blue (315-500 nm) and UV-B (280-315 nm) radiation in plants, respectively. While the roles of CRYs and UVR8 have been studied in separate controlled environment experiments, little is known about the interaction between these photoreceptors. Here, Arabidopsis thalian...
Article
Arabidopsis thaliana cyclic nucleotide-gated ion channel gene 4 (AtCNGC4)loss-of-function mutant dnd2 exhibits elevated accumulation of salicylic acid (SA), dwarfed morphology, reduced hypersensitive response (HR), altered disease resistance and spontaneous lesions on plant leaves. An orthologous barley mutant, nec1, has been reported to over-accum...
Preprint
Full-text available
The phytohormone strigolactone controls branching in Arabidopsis thaliana, but in recent years it has been shown to also affect many other plant functions. We previously showed that the strigolactone perception mutant max2 has increased susceptibility to plant pathogenic bacteria as a result of increased stomatal conductance as well as alterations...
Article
Full-text available
Reactive oxygen species (ROS)-dependent signaling pathways from chloroplasts and mitochondria merge at the nuclear protein RADICAL-INDUCED CELL DEATH1 (RCD1). RCD1 interacts in vivo and suppresses the activity of the transcription factors ANAC013 and ANAC017, which mediate a ROS-related retrograde signal originating from mitochondrial complex III....
Article
Full-text available
Reactive oxygen species (ROS) are key signalling intermediates in plant metabolism, defence, and stress adaptation. In plants, both the chloroplast and mitochondria are centres of metabolic control and ROS production, which coordinate stress responses in other cell compartments. The herbicide and experimental tool, methyl viologen (MV) induces ROS...
Preprint
Full-text available
Reactive oxygen species (ROS) are key signalling intermediates in plant metabolism, defence, and stress adaptation. The chloroplast and mitochondria are centres of metabolic control and ROS production, which coordinate stress responses in other cell compartments. The herbicide and experimental tool, methyl viologen (MV) induces ROS generation in th...
Article
Respiration in leaves and the continued elevation in the atmospheric CO2 concentration cause CO2‐mediated reduction in stomatal pore apertures. Several mutants have been isolated for which stomatal responses to both abscisic acid (ABA) and CO2 are simultaneously defective. However, there are only few mutations that impair the stomatal response to e...
Article
Full-text available
Stomata, small pores on the surfaces of leaves formed by a pair of guard cells, adapt rapidly to changes in the environment by adjusting the aperture width. As a long‐term response, the number of stomata is regulated during stomatal development. The hormone abscisic acid (ABA) regulates both processes. In ABA mediated guard cell signaling the prote...
Preprint
Stomata, small pores on the surfaces of leaves formed by a pair of guard cells, adapt rapidly to changes in the environment by adjusting the aperture width. As a long term response, the number of stomata is regulated during stomatal development. The hormone abscisic acid (ABA) regulates both processes. In ABA mediated guard cell signaling the prote...
Preprint
Full-text available
Signaling from chloroplasts and mitochondria, both dependent on reactive oxygen species (ROS), merge at the nuclear protein RADICAL-INDUCED CELL DEATH1 (RCD1). ROS produced in the chloroplasts affect the abundance, thiol redox state and oligomerization of RCD1. RCD1 directly interacts in vivo with ANAC013 and ANAC017 transcription factors, which ar...
Article
Full-text available
Pollen tubes (PTs) are characterized by having tip-focused cytosolic calcium ion (Ca2+) concentration ([Ca2+]cyt) gradients, which are believed to control PT growth. However, the mechanisms by which the apical [Ca2+]cyt orchestrates PT growth are not well understood. Here, we aimed to identify these mechanisms by combining reverse genetics, cell bi...
Article
This is a protocol for isolation of guard cell enriched samples from Arabidopsis thaliana plants for RNA extraction. Leaves are blended in ice-water and filtered through nylon mesh to obtain guard cell enriched fragments. With guard cell enriched samples, gene expression analysis can be done, e.g., comparing different gene expression levels in guar...
Article
Plants live in a world where they are challenged by abiotic and biotic stresses. In response to unfavorable conditions or an acute challenge like a pathogen attack, plants employ various signaling pathways that regulate expression of defense genes and other mechanisms to provide resistance or stress adaptation. Identification of the regulatory step...
Article
Full-text available
Silver birch (Betula pendula) is a pioneer boreal tree that can be induced to flower within 1 year. Its rapid life cycle, small (440-Mb) genome, and advanced germplasm resources make birch an attractive model for forest biotechnology. We assembled and chromosomally anchored the nuclear genome of an inbred B. pendula individual. Gene duplicates from...
Article
Proper stomatal responses are essential for plant function in an altered environment. The core signaling pathway for abscisic acid (ABA)-induced stomatal closure involves perception of the hormone that leads to the activation of guard cell anion channels by the protein kinase OPEN STOMATA1 (OST1). Several other regulators are suggested to modulate...
Article
Full-text available
Plants are exposed to abiotic and biotic stress conditions throughout their lifespans that activates various defense programs. Programmed cell death (PCD) is an extreme defense strategy the plant uses to manage unfavorable environments as well as during developmentally induced senescence. Here we investigated the role of leaf age on the regulation...
Data
Primer information and amplification efficiencies for qPCR analyses. (XLSX)
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...
Article
Full-text available
Biotic stress factors pose a major threat to plant health and can significantly deteriorate plant productivity by impairing the physiological functions of the plant. To combat the wide range of pathogens and insect herbivores, plants deploy converging signalling pathways, where counteracting activities of protein kinases and phosphatases form a bas...
Article
The cuticle is the outer physical barrier of aerial plant surfaces and an important interaction point between plants and the environment. Many environmental stresses affect cuticle formation, yet the regulatory pathways involved remain undefined. We used a genetics and gene expression approach in Arabidopsis thaliana to define an abscisic acid (ABA...
Article
Full-text available
As plants are sessile organisms that have to attune their physiology and morphology continuously to varying environmental challenges in order to survive and reproduce, they have evolved complex and integrated environment–cell, cell–cell, and cell–organelle signalling circuits that regulate and trigger the required adjustments (such as alteration of...
Article
The cuticle plays a critical role in plant survival during extreme drought conditions. There are, however, surprisingly, many gaps in our understanding of cuticle biosynthesis. An Arabidopsis thaliana T-DNA mutant library was screened for mutants with enhanced transpiration using a simple condensation spot method. Five mutants, named cool breath (c...
Article
Full-text available
Background: To survive in a changing environment plants constantly monitor their surroundings. In response to several stresses and during photorespiration plants use reactive oxygen species as signaling molecules. The Arabidopsis thaliana catalase2 (cat2) mutant lacks a peroxisomal catalase and under photorespiratory conditions accumulates H2O2, w...