Biology subjects

Takac, T.

Publications and source records attributed to Takac, T..

7 recordsLinked to original sources

bioRxiv2026

Stomatal movement in Arabidopsis is driven by guard cell-localized and copper-insensitive CSD1 splice variant

Copper (Cu) is an essential micronutrient whose bioavailability is strongly affected by soil physicochemical properties. During evolution, plants have developed mechanisms to flexibly adjust their metabolism to Cu status. Superoxide dismutases (SODs), including Cu/ZnSOD1 (CSD1) and FeSOD1 (FSD1), are key antioxidant enzymes regulated in Cu dependent manner in Arabidopsis thaliana. Examination of CSD1 cellular distribution and activity revealed that CSD1 is a nuclear and cytosolic SOD whose abundance and activity respond to Cu availability inversely to FSD1. Combined microscopic and biochemical analyses of Cu-dependent dynamics revealed that, unlike FSD1, CSD1 localization in guard cells (GCs) remains independent of Cu availability. CSD1 escapes miR398-mediated regulation in GCs through a cell type-specific splice variant (CSD1.2) that carries an altered miR398-binding site. In silico analyses indicate that this mechanism is also present in crop species. Functionally, the csd1 mutant showed reduced sensitivity to abscisic acid (ABA)-induced stomatal closure, a phenotype rescued by reintroducing CSD1. Biochemical and reactive oxygen species (ROS) level analyses indicate that CSD1.2 most likely acts independently of its canonical enzymatic activity in GCs and functions upstream of the ROS burst in the ABA signaling pathway. Together, we present a novel, cell-type-specific mechanism that safeguards ABA-driven stomatal closure under fluctuating Cu supply.

plant biology↗

bioRxiv2025

Protein and genetic interactions between RACK1A and FSD1 modulate plant development and stress granule-dependent response to salt in Arabidopsis.

The generation of reactive oxygen species (ROS) and their regulation by antioxidant enzymes such as IRON SUPEROXIDE DISMUTASE 1 (FSD1) are critical for managing plant responses to salt stress. However, the protein networks modulating ROS levels during salt stress remain incompletely understood. Our co-immunoprecipitation analysis identified the FSD1 as an interaction partner of the scaffolding protein RECEPTOR FOR ACTIVATED C KINASE 1A (RACK1A). Bimolecular fluorescence complementation analyses revealed that RACK1A interacts with FSD1 predominantly in the cytoplasm. Despite elevated FSD1 activity in rack1a mutants, the abundance of FSD1 protein remained unchanged. Computational predictions of interaction interfaces suggested that RACK1A may interfere with the catalytic site of FSD1. Advanced fluorescence microscopy and genetic studies further confirmed localization and relocation patterns of RACK1A and FSD1 during salt stress responses. Additionally, we found that the RACK1A-FSD1 module was involved in root hair tip growth, highlighting the developmental significance of this interaction. While rack1a mutants exhibited salt resilience, fsd1-1 rack1a-1 double mutant displayed reduced salt stress resistance compared to rack1a single mutant, which was substantiated by deregulation of ROS levels. RACK1A and FSD1 accumulated in cycloheximide-sensitive structural condensates in the cytoplasm that colocalized with the stress granule marker protein TSN in roots. However, RACK1A knock-out completely abolished salt-stress-dependent relocation of FSD1 to structural condensates, suggesting that RACK1A recruits FSD1 to these stress granules. Thus, this study uncovers an entirely novel mechanism for the regulation of RACK1/FSD1-dependent antioxidant defense in response to salt stress in Arabidopsis.

plant biology↗

bioRxiv2023

Remodelling of cytoskeleton and plasma membrane proteins contributes to drought sensitivity of Arabidopsis rhd2 mutant

NADPH oxidases are enzymes localised in the plasma membrane and emitting superoxide to the extracellular space. By production of superoxide as one type of reactive oxygen species (ROS), they exert pleiotropic functions in plant development and various stress responses. Arabidopsis thaliana RESPIRATORY BURST OXIDASE HOMOLOG PROTEIN C/ROOT HAIR DEFECTIVE 2 (AtRBOHC/RHD2) is an NADPH oxidase with preferential gene expression in roots. Polar localisation and ROS production by this enzyme are essential for root hair elongation. However, the proteome-wide and physiological consequences of RBOHC/RHD2 mutations are unknown. To find out potential new functions of AtRBOHC/RHD2, we employed a differential proteomic analysis of Arabidopsis rhd2-1 mutant, carrying a loss-of-function mutation in RBOHC/RHD2. Proteomic analyses that were validated with independent biochemical, phenotypical and advanced microscopy methods, showed quantitative deregulation of proteins involved in abiotic and biotic stress response, metabolism, vesicular transport and cell wall modification. Considerable differences in the differential proteomes between roots and above-ground parts were found in the mutant. The altered abundance of aquaporins and homeostasis of transmembrane pumps and transporters most likely determine the higher sensitivity of Arabidopsis rhd2-1 mutant to drought. HighlightProteomics and advanced microscopy reveal that the drought sensitivity of Arabidopsis mutant in ROOT HAIR DEFECTIVE 2 is linked to altered homeostasis of plasma membrane proteins and cytoskeleton remodelling.

plant biology↗

bioRxiv2022

Knockout of mitogen-activated protein kinase 3 causes barley root resistance against Fusarium graminearum.

The roles of mitogen-activated protein kinases (MAPKs) in plant-fungal pathogenic interactions are less understood in crops. Here, microscopic, phenotyping, proteomic and biochemical analyses revealed that independent TALEN-based knockout lines of Hordeum vulgare MITOGEN-ACTIVATED PROTEIN KINASE 3 (HvMPK3 KO) were resistant against Fusarium graminearum infection. When co-cultured with roots of the HvMPK3 KO lines, F. graminearum hyphae were excluded to the extracellular space, the growth pattern of hyphae was considerably deregulated, mycelia development was less efficient and number of appressoria and their penetration potential were significantly reduced. Intracellular penetration of hyphae was preceded by the massive production of reactive oxygen species (ROS) in attacked cells of the wild type, but it was mitigated in the HvMPK3 KO lines. Suppression of ROS production in these lines coincided with the elevated abundances of catalase and ascorbate peroxidase. Moreover, differential proteomic analysis revealed downregulation of defense-related proteins in wild type, and the upregulation of peroxidases, lipid transfer proteins, and cysteine proteases in HvMPK3 KO lines after 24h of F. graminearum inoculation. Consistently with proteomic analysis, microscopic observations showed an enhanced suberin accumulation in roots of HvMPK3 KO lines, most likely contributing to the arrested infection by F. graminearum. These results suggest that TALEN-based knockout of HvMPK3 leads to the barley root resistance against Fusarium root rot.

plant biology↗

bioRxiv2021

Arabidopsis iron superoxide dismutase 1 protects against methyl viologen-induced oxidative stress in a copper-dependent manner

Iron superoxide dismutase 1 (FSD1) was recently characterized as a plastidial, cytoplasmic, and nuclear superoxide dismutase with osmoprotective and antioxidative functions. However, its role in oxidative stress tolerance is not well understood. Here, we characterized the role of FSD1 in response to methyl viologen (MV)-induced oxidative stress in Arabidopsis thaliana. The findings demonstrated that the antioxidative function of FSD1 depends on the availability of Cu2+ in growth media. Prolonged MV exposure led to a decreased accumulation rate of superoxide, higher levels of hydrogen peroxide production, and higher protein carbonylation in the fsd1 mutants and transgenic plants lacking a plastidial pool of FSD1, compared to the wild type. MV led to a rapid increase in FSD1 activity, followed by a decrease. Chloroplastic localization of FSD1 is necessary for these changes. Proteomic analysis showed that the sensitivity of the fsd1 mutants coincided with decreased abundance of ferredoxin and light PSII harvesting complex proteins, with altered levels of signaling proteins. Collectively, the study provides evidence for the conditional antioxidative function of FSD1 and its possible role in signaling.

plant biology↗

bioRxiv2020

Single amino acid exchange in ACTIN2 confers increased tolerance to oxidative stress in Arabidopsis der1-3 mutant

Single-point mutation in the ACTIN2 gene of der1-3 mutant revealed that ACTIN2 is an essential actin isovariant required for root hair tip growth, and leads to shorter, thinner and more randomly oriented actin filaments in comparison to wild-type C24 genotype. Actin cytoskeleton has been linked to plant defence against oxidative stress, but it is not clear how altered structural organization and dynamics of actin filaments may help plants to cope with oxidative stress. In this study, we characterized seed germination, root growth, plant biomass, actin organization and antioxidant activity of der1-3 mutant under oxidative stress induced by paraquat and H2O2. Under these conditions, plant growth was better in der1-3 mutant, while actin cytoskeleton in der1-3 carrying pro35S::GFP:FABD2 construct showed lower bundling rate and higher dynamicity. Biochemical analyses documented lower degree of lipid peroxidation, elevated capacity to decompose superoxide and hydrogen peroxide. These results support the view that der1-3 mutant is more resistant to oxidative stress. Single amino acid exchange in mutated ACTIN2 protein (Cys to Arg at the position 97) is topologically exposed to the protein surface and we propose that this might alter protein post-translational modifications and/or protein-protein interactions, leading to enhanced tolerance of der1-3 mutant against oxidative stress. HighlightTopological position of one amino acid exchanged in the ACTIN2 protein structure in der1-3 mutant enhanced tolerance to oxidative stress through increased capacity to decompose reactive oxygen species, lower bundling and enhanced dynamicity of the actin cytoskeleton.

plant biology↗

bioRxiv2020

FSD1: a plastidial, nuclear and cytoplasmic enzyme relocalizing to the plasma membrane under salinity

Here, we aimed to resolve the developmental expression and subcellular localization of Arabidopsis iron superoxide dismutase FSD1, which belongs to the family of superoxide dismutases (SODs), prominent enzymes decomposing superoxide anion and determining abiotic stress tolerance. We found that fsd1 knockout mutants exhibit reduced lateral root number and that this phenotype was complemented by proFSD1::GFP:FSD1 and proFSD1::FSD1:GFP constructs. Light sheet fluorescence microscopy revealed a temporary accumulation of FSD1-GFP at the site of endosperm rupture during seed germination. In emerged roots, FSD1-GFP showed the highest abundance in cells of the lateral root cap, columella, and endodermis/cortex initials. The largest subcellular pool of FSD1-GFP was localized in the plastid stroma, while it was also located in the nuclei and cytoplasm. FSD1 is crucial for seed germination and salt stress tolerance, which is tightly coupled with FSD1-GFP subcellular relocation to the plasma membrane. FSD1 is most likely involved in superoxide decomposition in the periplasm. This study suggests a new osmoprotective function of SODs in plants.

plant biology↗