Biology subjects

Frachisse, J.-M.

Publications and source records attributed to Frachisse, J.-M..

4 recordsLinked to original sources

bioRxiv2025

Spatiotemporal Analysis Reveals Mechanisms Controlling Reactive Oxygen Species and Calcium Interplay Following Root Compression

Mechanical stimulation of the root triggers signal transduction involving Reactive Oxygen Species (ROS) and calcium, but their relationships are unclear. This study aims to clarify the temporal and spatial interrelations between calcium and ROS following a localized lateral compression of the root. We combined a microfluidic valve rootchip to apply controlled compression, with fluorescent probes and wide-field or confocal microscopy to monitor H2O2 and calcium dynamics in root tissues simultaneously. Pharmacological inhibitors were used to investigate the causal links between H2O2 and calcium responses. In response to compression, we observed transient H2O2 accumulation, with characteristics similar to the calcium response observed previously in the same microfluidic system. H2O2 and calcium response occurred in 3 kinetic phases: a fast calcium increase relying on mechanosensitive channels and external calcium entry, followed by a long-lasting H2O2 accumulation and a slow calcium increase depending on NADPH oxidase activity. H2O2 accumulated in all root tissues while calcium increases were confined to the root center. These results suggest that two mechanotransduction mechanisms are involved in root response to compression. One mechanism relies on plasma membrane mechanosensitive channels, triggering a fast calcium increase. Another independent mechanism, relying on FERONIA, induces H2O2 accumulation, which drives the slower secondary calcium increase.

plant biology↗

bioRxiv2025

The Rapid Mechanically Activated (RMA) channel transduces increases in plasma membrane tension into transient calcium influx

O_LIPlants respond to mechanical stimuli by a rapid increase in cytosolic calcium. The intensity and kinetics of the calcium changes define calcium signatures important for biological responses . In this study, we determine the properties of a calcium permeable force-gated channel localized at the plasma membrane called Rapid Mechanically Activated (RMA). C_LIO_LIUsing patch-clamp and pressure-clamp, we characterized the kinetics of activation and inactivation of RMA channel upon stimulation by pulses of pressure applied onto the plasma membrane. Combining repetitive pressure pulse protocols at different frequencies with modeling, we investigated the channels capacity to transduce high frequency mechanical stimuli. C_LIO_LIRMA channel rapidly activates in response to membrane tension, then it inactivates during prolonged stimulation. Upon repeated stimulations, RMA current amplitude decreases irreversibly indicating that undergoes adaptation. The channel kinetics may be modeled with four chemical states and the model predicts that it behaves as a pass band filter in the 10 Hz - 1 kHz range. C_LIO_LIIn conclusion, due to its activation/inactivation characteristics, RMA channel is a candidate to mediate cytosolic calcium signaling in response to mechano-stimulation. Its adaptation and filtering properties suggest its involvement in the transduction of high frequency mechanical stimulation such as those produced by insects vibrations. C_LI

plant biology↗

bioRxiv2023

Local compression of the root in a microfluidic device triggers a calcium signal

Throughout their life, plant root are submitted to mechanical stresses due to pressure exerted by the soil. So far, few studies addressed root cell deformation and calcium signaling elicited by soil compression. In this study, we designed a microchip inspired by pneumatic microvalve concept in order to deliver a lateral pressure to the root of a plant expressing the RGECO1-mTurquoise calcium reporter. Lateral pressure applied on the root induced a moderate elastic deformation of root cortical cells and elicited a multicomponent calcium signal at the onset of the pressure pulse, followed by a second one at the release of the pressure. This indicates that straining rather than stressing of tissues is relevant to trigger the calcium signal. The calcium elevation was restricted to the tissue under pressure and did not propagate. Additionally, the calcium signals exhibited a remarkable attenuation upon repetitive stimulations. Highlights- A microvalve concept mimicking lateral soil pressure was developed. - Non-damaging lateral compression of the root induces an elastic deformation of cortical cells. - A multicomponent calcium signal is elicited at the onset of a pressure pulse and upon release of the pressure. - Straining rather than stressing of tissues is relevant to trigger the calcium signal. - The calcium signal is localized at the tissue under pressure and does not propagate. - Calcium signals exhibit a remarkable attenuation upon repetitive stimulations.

plant biology↗

bioRxiv2019

Transduction of mechanical cellular oscillation by the plasma-membrane mechanosensitive channel MSL10

Throughout their life, plants are submitted to recurrent cyclic mechanical loading due to wind. The resulting passive oscillation movements of stem and foliage is an important phenomenon for biological and ecological issues such as photosynthesis optimization 1-3 and thermal exchange 4. The induced motions at plant scale are well described and analyzed, with oscillations at typically 1 to 3 Hz in trees 5-10. However, the cellular perception and transduction of such recurring mechanical signals remains an open question. Multimeric protein complexes forming mechanosensitive (MS) channels embedded in the membrane provide an efficient system to rapidly convert mechanical tension into electrical signal 11. Here we show that the plasma membrane mechanosensitive channel MscS-LIKE 10 (MSL10) from the model plant Arabidopsis thaliana responds to pulsed membrane stretching with rapid activation and relaxation kinetics in the range of one second. Under sinusoidal membrane stretching MSL10 presents a greater activity than under static stimulation and behaves as a large bandpass oscillation \"follower\" without filtering the signal in the range of 0.3 to 3 Hz. With a localization in aerial organs naturally submitted to oscillations, our results suggest that the mechanosensitive channel MSL10 represents a molecular component of a universal system of oscillatory perception in plants.

plant biology↗