Les séminaires ont lieu sur le Campus Montpellier SupAgro/INRA de La Gaillarde (2, place P. Viala Montpellier)
Jeudi 12 mars 2020 à 14h00 – Salle 106 (coeur d’École)
(Department of Botany, University of Wisconsin, Birge Hall, 430 Lincoln Drive, Madison, WI 53706, USA)
Leaf-to-leaf long-distance signaling in response to localized temperature changes in Arabidopsis thaliana
In plants, local and long-distance (systemic) signaling pathways forms a complex network allowing the integration of environmental conditions. Depending the nature of sensed stimuli and their criticality for development or survival, plants set up specific molecular and/or physiological acclimation responses, at either whole plant scale or very specific locations.
Calcium is a major component of both local and systemic signaling pathways in plants. Technical advances (in both imaging and genetic sensors) give us the opportunity to observe changes in [Ca2+]Cyt in real-time and in intact tissue from cellular scale to whole plant level. It recently helped to the characterization of two genes encoding ion channels of the GLUTAMATE RECEPTOR-LIKE family (GLR3.3 and GLR3.6) involved in the propagation of long-distance calcium and electrical signals in response to wounding (Toyota M. et al., 2018, Science; Nguyen CT. et al., 2018, P.N.A.S.).
Here, we propose to revisit some aspects of plant’s responses to temperature changes, and more precisely that of systemic low temperature signalling in Arabidopsis. The process of cold acclimation has been extensively studied and several keys actors identified. However, if the process of cold acclimation has been shown to be partially mediated by systemic signals, the nature and precise role of those signals are still to investigate.
We developed several devices to expose plants to a localized cold stimulus or gradient. Using calcium imaging and molecular approaches, we show that a localized cold stimulus on a single leaf induces an increase of [Ca2+]Cyt in that leaf, but also in distal leaves (that are not exposed to temperature variation).
We then monitored the expression level of potential targets of long-distance calcium signaling (among early cold-responsive genes) and confirm that the molecular cold response is tightly regulated in each leaf of the plant. This regulation is depending on the temperature others leaves of the rosette are exposed to. Those results supports the existence and importance of a systemic low temperature signaling in Arabidopsis.