Climate change-induced stressors such as extreme temperatures negatively affect plant growth and development. Therefore, methods are needed to improve plant tolerance to abiotic stresses. The aim of this study was to evaluate whether the foliar application of putrescine (Put) and a chitosan-putrescine nanocomposite (Ch-Put) can modulate the antioxidant response and membrane properties of lettuce under chilling stress. In this study, Put and Ch-Put were applied via foliar spraying at two concentrations (1 mM and 2.5 mM), and after treatment, the plants were placed in a phytotron at 4 °C and 20 °C. Changes in the properties of the cell membranes were assessed in the seedlings. Additionally, the antioxidant enzymatic activity and content of nonenzymatic bioactive compounds were evaluated. The results indicated that the use of Put and Ch-Put influenced the permeability and fluidity of the lipid membranes, which also depended on the treatment temperature. An increase in Alim (all treatments) and a decrease in Cs⁻1 values (Put and Ch-Put at a concentration of 2.5 mM) were observed at 4 °C, suggesting looser packing and increased elasticity of cell membranes, facilitating the metabolic and physiological adaptation of plants to stress. The treatment of chilled plants with Put and Ch-Put resulted in increased contents of proline, carbohydrates, glutathione, phenolics and L-ascorbic acid, as well as increased activity of several antioxidant enzymes, such as catalase (CAT) and ascorbate peroxidase (APX), which could contribute to increased tolerance to stress. The strongest effects were observed for Put at concentrations of 1 mM and 2.5 mM and Ch-Put at the 2.5 mM concentration, suggesting the potential use of these substances in strategies to increase plant tolerance to chilling stress.

• Klíčová slova
• Lactuca sativa, Antioxidants, Low-temperature stress, Nanocomposites, Plasma membrane, Polyamine,
• MeSH
• antioxidancia metabolismus   MeSH
• buněčná membrána metabolismus   účinky léků   MeSH
• chitosan * farmakologie   chemie   MeSH
• fyziologický stres * účinky léků   MeSH
• nanokompozity * chemie   MeSH
• nízká teplota MeSH
• putrescin * farmakologie   chemie   MeSH
• reakce na chladový šok * účinky léků   MeSH
• salát (hlávkový) * účinky léků   metabolismus   fyziologie   růst a vývoj   MeSH
• semenáček * účinky léků   metabolismus   růst a vývoj   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antioxidancia MeSH
• chitosan * MeSH
• putrescin * MeSH

The photosynthesis-induced accumulation of reactive oxygen species in chloroplasts can lead to oxidative stress, triggering changes in protein synthesis, degradation, and the assembly/disassembly of protein complexes. Using shot-gun proteomics, we identified methyl viologen-induced changes in protein abundance in wild-type Arabidopsis and oxidative stress-hypersensitive fsd1-1 and fsd1-2 knockout mutants, which are deficient in IRON SUPEROXIDE DISMUTASE 1 (FSD1). The levels of proteins that are localized in chloroplasts and the cytoplasm were modified in all lines treated with methyl viologen. Compared with the wild-type, fsd1 mutants showed significant changes in metabolic protein and chloroplast chaperone levels, together with increased ratio of cytoplasmic, peroxisomal, and mitochondrial proteins. Different responses in proteins involved in the disassembly of photosystem II-light harvesting chlorophyll a/b binding proteins were observed. Moreover, the abundance of PATELLIN 4, a phospholipid-binding protein enriched in stomatal lineage, was decreased in response to methyl viologen. Reverse genetic studies using patl4 knockout mutants and a PATELLIN 4 complemented line indicate that PATELLIN 4 affects plant responses to oxidative stress by effects on stomatal closure.

• Klíčová slova
• Arabidopsis, IRON SUPEROXIDE DISMUTASE 1, PATELLIN 4, chloroplast, methyl viologen, oxidative stress, photosynthesis, plasma membrane, proteomics,
• MeSH
• Arabidopsis * metabolismus   MeSH
• chlorofyl a metabolismus   farmakologie   MeSH
• chloroplasty metabolismus   MeSH
• fotosyntéza MeSH
• oxidační stres MeSH
• paraquat farmakologie   metabolismus   MeSH
• proteiny huseníčku * genetika   metabolismus   MeSH
• proteom metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• chlorofyl a MeSH
• paraquat MeSH
• proteiny huseníčku * MeSH
• proteom MeSH

The regulation of reactive oxygen species (ROS) levels in plants is ensured by mechanisms preventing their over accumulation, and by diverse antioxidants, including enzymes and nonenzymatic compounds. These are affected by redox conditions, posttranslational modifications, transcriptional and posttranscriptional modifications, Ca2+, nitric oxide (NO) and mitogen-activated protein kinase signaling pathways. Recent knowledge about protein-protein interactions (PPIs) of antioxidant enzymes advanced during last decade. The best-known examples are interactions mediated by redox buffering proteins such as thioredoxins and glutaredoxins. This review summarizes interactions of major antioxidant enzymes with regulatory and signaling proteins and their diverse functions. Such interactions are important for stability, degradation and activation of interacting partners. Moreover, PPIs of antioxidant enzymes may connect diverse metabolic processes with ROS scavenging. Proteins like receptor for activated C kinase 1 may ensure coordination of antioxidant enzymes to ensure efficient ROS regulation. Nevertheless, PPIs in antioxidant defense are understudied, and intensive research is required to define their role in complex regulation of ROS scavenging.

• Klíčová slova
• antioxidant enzymes, plants, protein-protein interactions, reactive oxygen species, receptor for activated C kinase 1, stress response,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Iron superoxide dismutase 1 (FSD1) was recently characterized as a plastidial, cytoplasmic, and nuclear enzyme with osmoprotective and antioxidant functions. However, the current knowledge on its role in oxidative stress tolerance is ambiguous. Here, we characterized the role of FSD1 in response to methyl viologen (MV)-induced oxidative stress in Arabidopsis thaliana. In accordance with the known regulation of FSD1 expression, abundance, and activity, the findings demonstrated that the antioxidant function of FSD1 depends on the availability of Cu2+ in growth media. Arabidopsis fsd1 mutants showed lower capacity to decompose superoxide at low Cu2+ concentrations in the medium. Prolonged exposure to MV led to reduced ascorbate levels and higher protein carbonylation in fsd1 mutants and transgenic plants lacking a plastid FSD1 pool as compared to the wild type. MV induced a rapid increase in FSD1 activity, followed by a decrease after 4 h long exposure. Genetic disruption of FSD1 negatively affected the hydrogen peroxide-decomposing ascorbate peroxidase in fsd1 mutants. Chloroplastic localization of FSD1 is crucial to maintain redox homeostasis. Proteomic analysis showed that the sensitivity of fsd1 mutants to MV coincided with decreased abundances of ferredoxin and photosystem II light-harvesting complex proteins. These mutants have higher levels of chloroplastic proteases indicating an altered protein turnover in chloroplasts. Moreover, FSD1 disruption affects the abundance of proteins involved in the defense response. Collectively, the study provides evidence for the conditional antioxidative function of FSD1 and its possible role in signaling.

• Klíčová slova
• Arabidopsis, FSD1, copper, ferredoxin, methyl viologen, oxidative stress, proteomics, superoxide dismutase,
• Publikační typ
• časopisecké články MeSH

The documentation of plant growth and development requires integrative and scalable approaches to investigate and spatiotemporally resolve various dynamic processes at different levels of plant body organization. The present update deals with vigorous developments in mesoscopy, microscopy and nanoscopy methods that have been translated to imaging of plant subcellular compartments, cells, tissues and organs over the past 3 years with the aim to report recent applications and reasonable expectations from current light-sheet fluorescence microscopy (LSFM) and super-resolution microscopy (SRM) modalities. Moreover, the shortcomings and limitations of existing LSFM and SRM are discussed, particularly for their ability to accommodate plant samples and regarding their documentation potential considering spherical aberrations or temporal restrictions prohibiting the dynamic recording of fast cellular processes at the three dimensions. For a more comprehensive description, advances in living or fixed sample preparation methods are also included, supported by an overview of developments in labeling strategies successfully applied in plants. These strategies are practically documented by current applications employing model plant Arabidopsis thaliana (L.) Heynh., but also robust crop species such as Medicago sativa L. and Hordeum vulgare L. Over the past few years, the trend towards designing of integrative microscopic modalities has become apparent and it is expected that in the near future LSFM and SRM will be bridged to achieve broader multiscale plant imaging with a single platform.

• MeSH
• fluorescenční mikroskopie metody   MeSH
• rostlinné buňky ultrastruktura   MeSH
• vývoj rostlin * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Single-point mutation in the ACTIN2 gene of the 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 the wild-type C24 genotype. The actin cytoskeleton has been linked to plant defense 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 root growth, plant biomass, actin organization and antioxidant activity of the der1-3 mutant under oxidative stress induced by paraquat and H2O2. Under these conditions, plant growth was better in the der1-3 mutant, while the actin cytoskeleton in the der1-3 carrying pro35S::GFP:FABD2 construct showed a lower bundling rate and higher dynamicity. Biochemical analyses documented a lower degree of lipid peroxidation, and an elevated capacity to decompose superoxide and hydrogen peroxide. These results support the view that the der1-3 mutant is more resistant to oxidative stress. We propose that alterations in the actin cytoskeleton, increased sensitivity of ACTIN to reducing agent dithiothreitol (DTT), along with the increased capacity to decompose reactive oxygen species encourage the enhanced tolerance of this mutant against oxidative stress.

• Klíčová slova
• ACTIN2, Arabidopsis, actin cytoskeleton, antioxidant capacity, der1–3 mutant, lipid peroxidation, oxidative stress, root hairs, single amino acid exchange,
• MeSH
• aktiny * genetika   metabolismus   MeSH
• Arabidopsis * genetika   metabolismus   MeSH
• kořeny rostlin * genetika   metabolismus   MeSH
• missense mutace * MeSH
• oxidační stres genetika   MeSH
• proteiny huseníčku * genetika   metabolismus   MeSH
• substituce aminokyselin MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• ACT2 protein, Arabidopsis MeSH Prohlížeč
• aktiny * MeSH
• proteiny huseníčku * MeSH

Reactive oxygen species (ROS) are signaling molecules essential for plant responses to abiotic and biotic stimuli as well as for multiple developmental processes. They are produced as byproducts of aerobic metabolism and are affected by adverse environmental conditions. The ROS content is controlled on the side of their production but also by scavenging machinery. Antioxidant enzymes represent a major ROS-scavenging force and are crucial for stress tolerance in plants. Enzymatic antioxidant defense occurs as a series of redox reactions for ROS elimination. Therefore, the deregulation of the antioxidant machinery may lead to the overaccumulation of ROS in plants, with negative consequences both in terms of plant development and resistance to environmental challenges. The transcriptional activation of antioxidant enzymes accompanies the long-term exposure of plants to unfavorable environmental conditions. Fast ROS production requires the immediate mobilization of the antioxidant defense system, which may occur via retrograde signaling, redox-based modifications, and the phosphorylation of ROS detoxifying enzymes. This review aimed to summarize the current knowledge on signaling processes regulating the enzymatic antioxidant capacity of plants.

• Klíčová slova
• antioxidant enzymes, calcium, mitogen-activated protein kinases, oxidative stress, plants, reactive oxygen species, signaling, stress,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH