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Poster

Session: Session 1 Presenting Authors at Posters (Evens)

P-358 - Contribution of root plastids to calcium-mediated signalling pathways triggered by microbial signals in Lotus japonicus

Tuesday, July 15, 2025
09:55 - 11:30  
Location: Confex Hall 3
Subcellular dynamics and signaling in host-microbe interactions
Calcium (Ca2+) is a crucial intracellular messenger in plant-microbe signal transduction pathways. Whereas Ca2+ signatures have been extensively investigated in the cytosol and nucleus of plant root cells, the elucidation of the role of additional intracellular compartments in Ca2+-mediated signalling during both mutualism and pathogenesis lags behind. Here, we focused on Ca2+ responses triggered by microbial signals in root plastids of Lotus japonicus. To this aim, a plastid stroma-targeted YFP-aequorin probe was stably expressed in L. japonicus roots to monitor stromal Ca2+ changes and visualize stromules, stroma-filled protrusions dynamically extending from plastid bodies in an endoplasmic reticulum (ER)-aided manner. Pharmacological treatments, together with Ca2+ measurement assays carried out in parallel in the cytosol and the ER, were used to investigate the origin and dissipation of the Ca2+ fluxes. Analyses of plants with different genetic backgrounds, impaired in either symbiotic pathways or stromule formation, provided first insights into the role of the observed plastidial Ca2+ elevations in microbial signals-triggered signalling cascades. Overall, the results support the notion that plant symbiotic signalling is intertwined with immunity-related signalling, and show that multiple organelles interact to shape intracellular Ca2+ dynamics during the response to microbial signals.