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.

• Keywords
• ACTIN2, Arabidopsis, actin cytoskeleton, antioxidant capacity, der1–3 mutant, lipid peroxidation, oxidative stress, root hairs, single amino acid exchange,
• MeSH
• Actins * genetics   metabolism   MeSH
• Arabidopsis * genetics   metabolism   MeSH
• Plant Roots * genetics   metabolism   MeSH
• Mutation, Missense * MeSH
• Oxidative Stress genetics   MeSH
• Arabidopsis Proteins * genetics   metabolism   MeSH
• Amino Acid Substitution MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• ACT2 protein, Arabidopsis MeSH Browser
• Actins * MeSH
• Arabidopsis Proteins * 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.

• Keywords
• antioxidant enzymes, calcium, mitogen-activated protein kinases, oxidative stress, plants, reactive oxygen species, signaling, stress,
• Publication type
• Journal Article MeSH
• Review MeSH

Hydrogen peroxide (H₂O₂) is steadily gaining more attention in the field of molecular biology research. It is a major REDOX (reduction⁻oxidation reaction) metabolite and at high concentrations induces oxidative damage to biomolecules, which can culminate in cell death. However, at concentrations in the low nanomolar range, H₂O₂ acts as a signalling molecule and in many aspects, resembles phytohormones. Though its signalling network in plants is much less well characterized than are those of its counterparts in yeast or mammals, accumulating evidence indicates that the role of H₂O₂-mediated signalling in plant cells is possibly even more indispensable. In this review, we summarize hydrogen peroxide metabolism in plants, the sources and sinks of this compound and its transport via peroxiporins. We outline H₂O₂ perception, its direct and indirect effects and known targets in the transcriptional machinery. We focus on the role of H₂O₂ in plant growth and development and discuss the crosstalk between it and phytohormones. In addition to a literature review, we performed a meta-analysis of available transcriptomics data which provided further evidence for crosstalk between H₂O₂ and light, nutrient signalling, temperature stress, drought stress and hormonal pathways.

• Keywords
• H2O2, growth and development, plant hormone, signalling, stress,
• MeSH
• Biological Transport MeSH
• Stress, Physiological MeSH
• Hydrogen Peroxide metabolism   MeSH
• Gene Expression Regulation, Plant MeSH
• Plant Growth Regulators genetics   metabolism   MeSH
• Plants genetics   metabolism   MeSH
• Signal Transduction * MeSH
• Transcriptome MeSH
• Plant Development * MeSH
• Publication type
• Journal Article MeSH
• Meta-Analysis MeSH
• Review MeSH
• Names of Substances
• Hydrogen Peroxide MeSH
• Plant Growth Regulators MeSH