DspA/E-Triggered Non-Host Resistance against E. amylovora Depends on the Arabidopsis GLYCOLATE OXIDASE 2 Gene

Deciphering peroxisomal reactive species interactome and redox signalling networks

Plant peroxisomes are highly dynamic organelles with regard to metabolic pathways, number and morphology and participate in different metabolic processes and cell responses to their environment. Peroxisomes from animal and plant cells house a complex system of reactive oxygen species (ROS) production associated to different metabolic pathways which are under control of an important set of enzymatic and non enzymatic antioxidative defenses. Nitric oxide (NO) and its derivate reactive nitrogen species (RNS) are also produced in these organelles. Peroxisomes can regulate ROS and NO/RNS levels to allow their role as signalling molecules. The metabolism of other reactive species such as carbonyl reactive species (CRS) and sulfur reactive species (SRS) in peroxisomes and their relationship with ROS and NO have not been explored in depth. In this review, we define a peroxisomal reactive species interactome (PRSI), including all reactive species ROS, RNS, CRS and SRS, their interaction and effect on target molecules contributing to the dynamic redox/ROS homeostasis and plasticity of peroxisomes, enabling fine-tuned regulation of signalling networks associated with peroxisome-dependent H₂O₂. Particular attention will be paid to update the information available on H₂O₂-dependent peroxisomal retrograde signalling and to discuss a specific peroxisomal footprint.

The role of photorespiration in plant immunity

To defend themselves in the face of biotic stresses, plants employ a sophisticated immune system that requires the coordination of other biological and metabolic pathways. Photorespiration, a byproduct pathway of oxygenic photosynthesis that spans multiple cellular compartments and links primary metabolisms, plays important roles in defense responses. Hydrogen peroxide, whose homeostasis is strongly impacted by photorespiration, is a crucial signaling molecule in plant immunity. Photorespiratory metabolites, interaction between photorespiration and defense hormone biosynthesis, and other mechanisms, are also implicated. An improved understanding of the relationship between plant immunity and photorespiration may provide a much-needed knowledge basis for crop engineering to maximize photosynthesis without negative tradeoffs in plant immunity, especially because the photorespiratory pathway has become a major target for genetic engineering with the goal to increase photosynthetic efficiency.

Fungal Effectoromics: A World in Constant Evolution

Effectors are small, secreted molecules that mediate the establishment of interactions in nature. While some concepts of effector biology have stood the test of time, this area of study is ever-evolving as new effectors and associated characteristics are being revealed. In the present review, the different characteristics that underly effector classifications are discussed, contrasting past and present knowledge regarding these molecules to foster a more comprehensive understanding of effectors for the reader. Research gaps in effector identification and perspectives for effector application in plant disease management are also presented, with a focus on fungal effectors in the plant-microbe interaction and interactions beyond the plant host. In summary, the review provides an amenable yet thorough introduction to fungal effector biology, presenting noteworthy examples of effectors and effector studies that have shaped our present understanding of the field.

Peroxisome-Mediated Reactive Oxygen Species Signals Modulate Programmed Cell Death in Plants

Peroxisomes are a class of simple organelles that play an important role in plant reactive oxygen species (ROS) metabolism. Experimental evidence reveals the involvement of ROS in programmed cell death (PCD) in plants. Plant PCD is crucial for the regulation of plant growth, development and environmental stress resistance. However, it is unclear whether the ROS originated from peroxisomes participated in cellular PCD. Enzymes involved in the peroxisomal ROS metabolic pathways are key mediators to figure out the relationship between peroxisome-derived ROS and PCD. Here, we summarize the peroxisomal ROS generation and scavenging pathways and explain how peroxisome-derived ROS participate in PCD based on recent progress in the functional study of enzymes related to peroxisomal ROS generation or scavenging. We aimed to elucidate the role of the peroxisomal ROS regulatory system in cellular PCD to show its potential in terms of accurate PCD regulation, which contribute to environmental stress resistance.

The oxidized cellooligosaccharides confer thermotolerance in Arabidopsis by priming ethylene via heat shock factor A2

Global climate change, especially heatwaves and aridity, is a major threat to agricultural production and food security. This requires common efforts from the scientific community to find effective solutions to better understand and protect the plant's vulnerabilities to high temperatures. The current study demonstrates the potential of cellooligosaccharides (COS), which are native and oxidized signaling molecules released by lytic polysaccharide monooxygenases (LPMO) enzymes during cell wall degradation by microbial pathogens. The extracellular perception of COS leads to the activation of damage-triggered immunity, often protecting the plant against biotic stress. However, how these signaling molecules affect abiotic stress tolerance is poorly understood. Here, we show that native COS and oxidized COS (oxiCOS) perception increase the transcript levels of several HEAT SHOCK FACTORS (HSFs) and HEAT SHOCK PROTEINS (HSPs) genes in Arabidopsis plants. However, only oxiCOS treatment triggers ethylene priming and increases thermotolerance. Furthermore, the function of the transcription factor HSFA2 is required for these processes. Altogether, our results indicate that the perception of Damage-Associated Molecular Patterns (DAMPs) may improve tolerance to adverse abiotic conditions, like exposure to high temperatures.