Biology subjects

Vothknecht, U. C.

Publications and source records attributed to Vothknecht, U. C..

7 recordsLinked to original sources

bioRxiv2026

CYSTM1, a drought-responsive cysteine-rich transmembrane module protein, negatively affects drought tolerance in Arabidopsis thaliana

Drought stress represents a major challenge for plant growth and survival, requiring coordinated regulation of physiological and molecular responses to maintain water balance. The cysteine-rich transmembrane module (CYSTM) family comprises a highly conserved group of small proteins whose functions in plant stress adaptation remain largely unknown. Here, we identified CYSTM1 (AT1G05340) as a drought-responsive gene in Arabidopsis thaliana whose expression increased in response to prolonged water deficit, osmotic stress, high salinity, and abscisic acid (ABA). Analysis of a loss-of-function T-DNA insertion mutant (cystm1) showed no growth phenotype compared to the wild-type under well-watered conditions. However, the mutant plants exhibited enhanced drought tolerance, whereas independent complementation lines restored the wild-type phenotype. The improved drought performance of the cystm1 plants was associated with reduced stomatal aperture and decreased transpiration. Mutant plants also displayed an enhanced seedling establishment under osmotic stress conditions. Loss of CYSTM1 altered ABA-associated responses at physiological and transcriptional level, resulting in reduced sensitivity to exogenous ABA and attenuated expression of ABA- and drought-responsive genes during water deficit. Co-expression analysis showed that genes with expression pattern similar to CYSTM1 include many genes related to drought response as well as other members of the CYSTM family. Further expression analyses revealed selective transcriptional reprogramming within the CYSTM family following the loss of CYSTM1, suggesting crosstalk or functional interdependence within the CYSTM gene family. Collectively, these findings identify CYSTM1 as a novel negative effector of drought tolerance.

plant biology↗

bioRxiv2025

Loss-of-function of the drought-induced genes GASA3 and AFP1 confers enhanced drought tolerance in Arabidopsis thaliana

Prolonged drought is a major challenge in plant growth, severely affecting development and yield. Enhancing drought tolerance is thus a highly desired goal for agriculture. Here, we report that the loss-of-function of two drought-induced genes, GASA3 and AFP1, significantly enhances drought tolerance in Arabidopsis thaliana. While constitutive expression of GASA3 and AFP1 increased drought sensitivity compared to wild type (WT) plants, a gasa3afp1 double mutant exhibited superior drought tolerance compared to the single mutants. Enhanced drought tolerance of gasa3, afp1 and gasa3afp1 is likely due to reduced water loss caused by smaller stomatal apertures and thus lower transpiration rates. Moreover, gasa3 and afp1 mutants accumulated higher levels of abscisic acid (ABA) under drought conditions than WT plants, concomitant with a stronger up-regulation of ABA-responsive genes such as RD29A/B, ABF2/3, and ABI5. The stronger ABA increase in the mutants seems to result from hydrolysis of abscisic acid-glucosyl ester (ABA-GE) from vacuolar stores via the {beta}-glucosidase BG2 rather than by de-novo biosynthesis. Promoter analysis revealed the presence of ABA-responsive and drought stress-related cis-acting elements within the GASA3 and AFP1 promoter regions. RT-qPCR confirmed that the expression of both genes increased under drought. However, GASA3 induction was significantly reduced in the absence of AFP1, suggesting that AFP1 is involved in the modulation of GASA3 expression. Our findings identify a novel AFP1/GASA3-driven control circuit that negatively regulates drought tolerance by suppressing stomatal closure and attenuating ABA signalling.

plant biology↗

bioRxiv2025

With or without a Ca2+ signal;A proteomics approach towards Ca2+ dependent and independent proteome changes in response to oxidative stress in A. thaliana

Calcium (Ca2+) and reactive oxygen species (ROS) are key secondary messengers in plant stress signaling, yet their interplay in regulating proteome-wide responses remains poorly understood. In this study, we employed label-free quantitative (LFQ) proteomics to investigate Ca2+-dependent and independent changes in the proteome of Arabidopsis thaliana leaves upon oxidative stress induced by hydrogen peroxide (H2O2). To dissect the role of Ca2+ signaling, we inhibited H2O2-induced Ca2+ transients by pretreatment with LaCl3, a plasma membrane Ca2+ channel blocker. We then analysed the proteome of plants treated with H202 or ddH2O after 10 and 30 min of treatment and detected 3724 and 3757 proteins, respectively. From these, 581 proteins showed significant changes in abundance after 10 min and 909 proteins after 30 min. Remarkably, the combined LaCl3 and H2O2 treatment resulted in the highest number of differentially abundant proteins (DAPs), indicating a strong attenuating effect of Ca2+ signaling on the oxidative stress response. Specifically responsive to only H2O2 were 37 and 57 proteins with distinct subsets of strictly Ca2+-dependent, partially Ca2+- dependent, and Ca2+-independent proteins. Notably, Ca2+-independent H2O2-responsive proteins predominantly showed increased abundance, while strictly Ca2+-dependent proteins exhibited decreased abundance, suggesting a role for Ca2+ signaling in protein degradation. Furthermore, three proteins--WLIM1, CYP97C1, and AGAP1--underwent Ca2+-dependent shifts between the two time points, pointing to a dynamic nature of Ca2+-regulated proteomic changes. This study provides novel insights into short-term Ca2+-dependent and independent regulation of the Arabidopsis leaf proteome in response to oxidative stress, identifying key stress-responsive proteins and potential new targets for further research on plant stress resilience mechanisms.

plant biology↗

bioRxiv2023

Stress Knowledge Map: A knowledge graph resource for systems biology analysis of plant stress responses

Stress Knowledge Map (SKM, https://skm.nib.si) is a publicly available resource containing two complementary knowledge graphs describing current knowledge of biochemical, signalling, and regulatory molecular interactions in plants: a highly curated model of plant stress signalling (PSS, 543 reactions) and a large comprehensive knowledge network (CKN, 488,390 interactions). Both were constructed by domain experts through systematic curation of diverse literature and database resources. SKM provides a single entrypoint for plant stress response investigations and the related growth tradeoffs. SKM provides interactive exploration of current knowledge. PSS is also formulated as qualitative and quantitative models for systems biology, and thus represents a starting point of a plant digital twin. Here, we describe the features of SKM and show, through two case studies, how it can be used for complex analyses, including systematic hypothesis generation, design of validation experiments, or to gain new insights into experimental observations in plant biology.

plant biology↗

bioRxiv2021

Constitutive expression of JASMONATE RESISTANT 1 elevates content of several jasmonates and primes Arabidopsis thaliana to better withstand drought

Jasmonates have a well-documented role in balancing the trade-off between plant growth and defense against biotic stresses. However, the role of jasmonate signaling under abiotic stress is less well studied. Here, we investigated the function of JASMONATE RESISTANT 1 (JAR1) in drought stress in Arabidopsis thaliana. JAR1 converts jasmonic acid (JA) to jasmonyl-L-isoleucine (JA-Ile), the major bioactive form of jasmonates. Comparison of a newly generated over-expression line (JAR1-OE) with jar1-11, a T-DNA insertion line in the JAR1 locus, and Col-0 revealed that constitutively increased JA-Ile production results in stunted growth and a delay in flowering. Upon water limitation, JAR1-OE plants retained more water in their leaves, showed reduced wilting and recovered better from drought stress than the wild type. By contrast, jar1-11 mutant plants were hypersensitive to drought. RNA-seq analysis and hormonal profiling of plants under control and drought stress conditions provided insight into the molecular reprogramming caused by the alteration in JA-Ile content. Especially JAR1-OE plants were affected in many adaptive systems related to drought stress, including stomatal density, stomatal aperture or the formation of reactive oxygen species (ROS). Overall, our data suggest that constitutively increased expression of JAR1 can prime Arabidopsis towards improved drought tolerance. One sentence summaryConstitutive expression of JAR1primes Arabidopsis thaliana to better withstand drought stress

plant biology↗

bioRxiv2020

Chloroplast-derived photo-oxidative stress causes changes in H2O2 and EGSH in other subcellular compartments

Metabolic fluctuations in chloroplasts and mitochondria can trigger retrograde signals to modify nuclear gene expression. Mobile signals likely to be involved are reactive oxygen species (ROS), which can operate protein redox switches by oxidation of specific cysteine residues. Redox buffers such as the highly reduced glutathione pool serve as reservoirs of reducing power for several ROS scavenging and ROS-induced damage repair pathways. Formation of glutathione disulfide (GSSG) and a shift of the glutathione redox potential (EGSH) towards less negative values is considered a hallmark of several stress conditions. Here we used the herbicide methyl viologen (MV) to generate ROS locally in chloroplasts of intact Arabidopsis seedlings and recorded dynamic changes in EGSH and H2O2 levels with the genetically-encoded biosensors Grx1-roGFP2 (for EGSH) and roGFP2-Orp1 (for H2O2) targeted to chloroplasts, the cytosol or mitochondria. Treatment of seedlings with MV caused a rapid oxidation in chloroplasts and subsequently also in the cytosol and mitochondria. The MV-induced oxidation was significantly boosted by illumination with actinic light and largely abolished by inhibitors of photosynthetic electron transport. In addition, MV also induced an autonomous oxidation in the mitochondrial matrix in an electron transport chain activity-dependent manner that was milder than the oxidation triggered in chloroplasts by the combination of MV and light. In vivo redox biosensing resolves the spatiotemporal dynamics of compartmental responses to local ROS generation and provide a basis for understanding how compartment-specific redox dynamics may operate in retrograde signaling and stress acclimation in plants. One sentence summaryMethyl viologen-induced photooxidative stress causes an increase of H2O2 and oxidation of glutathione in chloroplasts, cytosol and mitochondria as well as autonomous oxidation in mitochondria.

plant biology↗

bioRxiv2019

A novel Ca2+-binding protein influences photosynthetic electron transport in Anabaena sp. PCC 7120

Ca2+ is a potent signalling molecule that regulates many cellular processes. In cyanobacteria, Ca2+ has been linked to cell growth, stress response and photosynthesis, and to the development of specialist heterocyst cells in certain nitrogen-fixing species. Despite this, the pathways of calcium signal transduction in cyanobacteria are poorly understood, and only a few protein components are known. The current study describes a previously unreported calcium-binding protein which was called the Calcium Sensor EF-hand (CSE), which is conserved in filamentous, nitrogen-fixing cyanobacteria. CSE is shown to bind calcium, which induces a conformational change in the protein structure. Poor growth of a strain of Anabaena sp. PCC 7120 overexpressing CSE was attributed to diminished photosynthetic performance. Transcriptomics, biophysics and proteomics analyses revealed modifications in the light-harvesting phycobilisome and photosynthetic reaction center-protein complexes, and downregulated respiration.

plant biology↗