ROS-dependent signaling pathways in plants and algae exposed to high light: Comparisons with other eukaryotes

Abstract Like all aerobic organisms, plants and algae co-opt reactive oxygen species (ROS) as signaling molecules to drive cellular responses to changes in their environment. In this respect, there is considerable commonality between all eukaryotes imposed by the constraints of ROS chemistry, similar metabolism in many subcellular compartments, the requirement for a high degree of signal specificity and the deployment of thiol peroxidases as transducers of oxidizing equivalents to regulatory proteins. Nevertheless, plants and algae carry out specialised signaling arising from oxygenic photosynthesis in chloroplasts and photoautotropism, which often induce an imbalance between absorption of light energy and the capacity to use it productively. A key means of responding to this imbalance is through communication of chloroplasts with the nucleus to adjust cellular metabolism. Two ROS, singlet oxygen (1O2) and hydrogen peroxide (H2O2), initiate distinct signaling pathways when photosynthesis is perturbed. 1O2, because of its potent reactivity means that it initiates but does not transduce signaling. In contrast, the lower reactivity of H2O2 means that it can also be a mobile messenger in a spatially-defined signaling pathway. How plants translate a H2O2 message to bring about changes in gene expression is unknown and therefore, we draw on information from other eukaryotes to propose a working hypothesis. The role of these ROS generated in other subcellular compartments of plant cells in response to HL is critically considered alongside other eukaryotes. Finally, the responses of animal cells to oxidative stress upon high irradiance exposure is considered for new comparisons between plant and animal cells

Temperature stress and redox homeostasis: The synergistic network of redox and chaperone system in response to stress in plants

A remarkable number of strategies has been developed by living organisms to mitigate conflict with environmental changes. The global environment rising with ambient temperature has a wide range of effects on plant growth, and therefore activation of various molecular defenses before the appearance of heat damage. Evidence revealed key components of stress that trigger enhanced tolerance, and some determinants for plant tolerance have been identified. The interplay between heat shock proteins (HSP) and redox proteins is supposed to be vital for the survival under extreme stress conditions. Any circumstance in which cellular redox homeostasis is disrupted can lead to the generation of reactive oxygen species (ROS) that are continuously generated in cells as an unavoidable consequence of aerobic life. Integrative network analysis of synthetic genetic interactions, protein-protein interactions, and functional annotations revealed many new functional processes linked to heat stress (HS) and oxidative stress (OS) tolerance, implicated upstream regulators activated by the either HS or OS, and revealed new connections between them. We present different models of acquired stress resistance to interpret the condition-specific involvement of genes. Considering the basic concepts and the recent advances, the following subsections provide an overview of calcium ion (Ca2+) and ROS interplay in abiotic signaling pathways; further we introduce several examples of chaperone and redox proteins that respond the change of cellular redox status under environmental circumstances. Thus, the involvement or contribution of redox proteins through the functional switching in conjunction with the HSP that prevent heat- and oxidative-induced protein aggregation in plants