Spatially and temporally distinct Ca2+ changes in Lotus japonicus roots orient fungal-triggered signalling pathways towards symbiosis or immunity.

Plants activate an immune or symbiotic response depending on the detection of distinct signals from root-interacting microbes. Both signalling cascades involve Ca2+ as a central mediator of early signal transduction. In this study, we combined aequorin- and cameleon-based methods to dissect the changes in cytosolic and nuclear Ca2+ concentration caused by different chitin-derived fungal elicitors in Lotus japonicus roots. Our quantitative analyses highlighted the dual character of the evoked Ca2+ responses taking advantage of the comparison between different genetic backgrounds: an initial Ca2+ influx, dependent on the LysM receptor CERK6 and independent of the common symbiotic signalling pathway (CSSP), is followed by a second CSSP-dependent and CERK6-independent phase, that corresponds to the well-known perinuclear/nuclear Ca2+ spiking. We show that the expression of immunity marker genes correlates with the amplitude of the first Ca2+ change, depends on elicitor concentration, and is controlled by Ca2+ storage in the vacuole. Our findings provide an insight into the Ca2+-mediated signalling mechanisms discriminating plant immunity- and symbiosis-related pathways in the context of their simultaneous activation by single fungal elicitors. © The Author(s) 2023. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Citation

Filippo Binci, Elisabetta Offer, Andrea Crosino, Ivan Sciascia, Jürgen Kleine-Vehn, Andrea Genre, Marco Giovannetti, Lorella Navazio. Spatially and temporally distinct Ca2+ changes in Lotus japonicus roots orient fungal-triggered signalling pathways towards symbiosis or immunity. Journal of experimental botany. 2024 Jan 10;75(2):605-619

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PMID: 37712520

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