Analysis of the subcellular localisation of lipoxygenase in legume and actinorhizal nodules

Variability in the Capacity to Produce Damage-Induced Aldehyde Green Leaf Volatiles among Different Plant Species Provides Novel Insights into Biosynthetic Diversity

Green leaf volatiles (GLVs) are commonly released by plants upon damage, thereby providing volatile signals for other plants to prepare against the major causes of damage, herbivory, pathogen infection, and cold stress. However, while the biosynthesis of these compounds is generally well understood, little is known about the qualities and quantities that are released by different plant species, nor is it known if release patterns can be associated with different clades of plants. Here, we provide a first study describing the damage-induced release of major GLVs by more than 50 plant species. We found major differences in the quantity and quality of those compounds between different plant species ranging from undetectable levels to almost 100 µg per gram fresh weight. We also found major shifts in the composition that correlate directly to the quantity of emitted GLV. However, we did not find any major patterns that would associate specific GLV release with distinct clades of plants.

Role of Jasmonates in Beneficial Microbe-Root Interactions

The phytohormone jasmonate (JA) modulates various defense and developmental responses of plants, and is implied in the integration of multiple environmental signals. Given its centrality in regulating plant physiology according to external stimuli, JA influences the establishment of interactions between plant roots and beneficial bacteria or fungi. In many cases, moderate JA signaling promotes the onset of mutualism, while massive JA signaling inhibits it. The output also depends on the compatibility between microbe and host plant and on nutritional or environmental cues. Also, JA biosynthesis and perception participate in the systemic regulation of mutualistic interactions and in microbe-induced resistance to biotic and abiotic stress. Here, we review our current knowledge of the role of JA biosynthesis, signaling, and responses during mutualistic root-microbe interactions.

Rapid phosphoproteomic and transcriptomic changes in the rhizobia-legume symbiosis

Symbiotic associations between legumes and rhizobia usually commence with the perception of bacterial lipochitooligosaccharides, known as Nod factors (NF), which triggers rapid cellular and molecular responses in host plants. We report here deep untargeted tandem mass spectrometry-based measurements of rapid NF-induced changes in the phosphorylation status of 13,506 phosphosites in 7739 proteins from the model legume Medicago truncatula. To place these phosphorylation changes within a biological context, quantitative phosphoproteomic and RNA measurements in wild-type plants were compared with those observed in mutants, one defective in NF perception (nfp) and one defective in downstream signal transduction events (dmi3). Our study quantified the early phosphorylation and transcription dynamics that are specifically associated with NF-signaling, confirmed a dmi3-mediated feedback loop in the pathway, and suggested "cryptic" NF-signaling pathways, some of them being also involved in the response to symbiotic arbuscular mycorrhizal fungi.