Thermo-priming triggers species-specific physiological and transcriptome responses in Mediterranean seagrasses

Heat-priming improves plants' tolerance to a recurring heat stress event. The underlying molecular mechanisms of heat-priming are largely unknown in seagrasses. Here, ad hoc mesocosm experiments were conducted with two Mediterranean seagrass species, Posidonia oceanica and Cymodocea nodosa. Plants were first exposed to heat-priming, followed by a heat-triggering event. A comprehensive assessment of plant stress response across different levels of biological organization was performed at the end of the triggering event. Morphological and physiological results showed an improved response of heat-primed P. oceanica plants while in C. nodosa both heat- and non-primed plants enhanced their growth rates at the end of the triggering event. As resulting from whole transcriptome sequencing, molecular functions related to several cellular compartments and processes were involved in the response to warming of non-primed plants, while the response of heat-primed plants involved a limited group of processes. Our results suggest that seagrasses acquire a primed state during the priming event, that eventually gives plants the ability to induce a more energy-effective response when the thermal stress event recurs. Different species may differ in their ability to perform an improved heat stress response after priming. This study provides pioneer molecular insights into the emerging topic of seagrass stress priming and may benefit future studies in the field.

HMN was supported by an SZN Ph.D. fellowship via the Open University. This work was funded by EPIC-SEA Project, Extra-Eu Scientific Research and Cooperation Grant of the SZN, by the project Marine Hazard, PON03PE_00203_1, Italian Ministry of Education, University and Research (MUR), by the project Assemble Plus EU-FP7 and partially by the European Union – NextGenerationEU. Project code CN_00000033, Concession Decree No. 1034 of June 17, 2022 adopted by the Italian Ministry of University and Research, CUP C63C22000520001, Project title “National Biodiversity Future Center - NBFC”. The work of LMG was partially supported by the project GRASSREC, PID2020-118144RB-C31 (Spanish Ministry of Science and Innovation). Authors are grateful for the precious support from Alex Santillán-Sarmiento, Ludovica Pedicini and Jessica Pazzaglia (SZN) for the mesocosm experiment.

Peer reviewed