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Leger, O.

Publications and source records attributed to Leger, O..

3 recordsLinked to original sources

Autophagy acts as a spatial organizer of cell-type-specific plant immunity

Effective plant immunity requires precise spatial coordination of immune responses across cell-types to restrict pathogens while preventing tissue damage, yet the intracellular pathways that organize this spatial architecture remain unknown. Here we show that autophagy serves as a spatial coordinator of immunity, partitioning and calibrating immune strategies across tissues during Pseudomonas syringae infection in Arabidopsis thaliana. Combining single-cell transcriptomics, cell-type-specific complementation, and live-cell imaging, we uncover distinct and opposing roles of autophagy across tissues. In guard cells, autophagy promotes pathogen-induced stomatal reopening by suppressing abscisic acid (ABA) signalling in part via autophagic turnover of the guard cell ABA receptor PYL4. In contrast, in mesophyll cells, autophagy restricts immune activation while simultaneously enabling effective immune execution: its loss enhances EDS1-PAD4-ADR1 pathway expression yet compromises PTI outputs. Mechanistically, bacterial infection triggers autophagic EDS1 turnover, supporting a model in which controlled EDS1 recycling facilitates HR elicitation. Cell-type-specific complementation reveals that PTI competence may involve coordinated autophagy across tissues, whereas mesophyll-autonomous autophagy is partially sufficient for HR execution. Together, these findings establish a framework in which spatial control of proteostasis orchestrates multicellular immune coordination, with broad implications for understanding how conserved degradation pathways regulate layered immunity across organisms.

plant biology↗

"Out of sight, out of mind". The antagonistic role of the transcriptional memory associated with repeated acoustic stimuli on the priming of plant defense.

BackgroundPriming plant immunity offers a powerful and sustainable strategy for crop protection, enabling plants to respond faster and more efficiently to threats. This increased readiness is driven by transcriptional memory--molecular mechanisms that store and recall stress responses, including protein accumulation, transcription factor activity, and epigenetic modifications. However, the interplay among transcriptional stress memory, its stability, and its broader impact on plant resistance remain poorly understood. ResultsHere, we reveal a tight link between transcriptional memory and defense priming in Arabidopsis thaliana exposed to repeated acoustic stimulations. Using a combination of experiments and computational modeling, we show that enhanced resistance to Sclerotinia sclerotiorum after three stimulations arises from three key mechanisms: (1) preemptive activation of defense pathways in noninoculated plants, (2) increased diversification of defense-related genes, and (3) gene priming. This heightened defense state is sustained by transcriptional stress memory across thousands of genes, which is likely orchestrated by transcription factor cascades. Challenging the conventional view that priming involves stepwise activation of distinct pathways, our findings suggest that priming instead results from the simultaneous modulation of a broad spectrum of defense pathways. This built-in redundancy enhances resilience, shielding primed plants from the genetic variability-driven resistance loss observed in naive plants. However, this same redundancy imposes strict limits on further enhancing the resistance. More frequent acoustic stimulations did not amplify the protective effect, and transcriptional memory faded within 1.5 days after stimulation ceased. ConclusionsBy integrating experimental and computational approaches, we present a genome-scale quantitative model of stress-induced gene regulation. Our results highlight the trade-offs inherent in transcriptional memory-driven priming, revealing both its potential and its limitations in optimizing plant immunity.

plant biology↗

Pathogen-derived mechanical cues regulate the spatio-temporal implementation of plant defense

How immune responses are activated and regulated is a central question in immunology. In addition to molecular signaling, recent work has shown that physical forces regulate the immune response of vertebrates by modifying transmembrane protein conformation and cell contact. Mechanical stress and strain produced by forces constitute physical cues perceived by cells instructing gene expression. Whether mechanical cues generated by pathogens during host colonization can trigger adaptive responses in plant cells remains elusive. We found that local and progressive variations of plant cell wall tension caused by fungal pathogen attacks are transmitted to neighboring healthy tissue around the infection site and trigger immunity in distal cells. This thigmoimmunity process requires the reorganization of cortical microtubules and contributes strongly to Arabidopsis disease resistance. One-Sentence SummaryActivation of plants immunity depends on fluctuations of mechanical tension caused by a fungal pathogen.

plant biology↗