Biology subjects

Martiniere, A.

Publications and source records attributed to Martiniere, A..

6 recordsLinked to original sources

bioRxiv2026

The role of reactive oxygen species and calcium signaling in antiviral defense in Arabidopsis

Plant viruses interfere with host signaling pathways, but it remains unclear how calcium (Ca2+) signaling, reactive oxygen species (ROS), and changes in the plasma membrane interact during viral infection. Here, we investigated how plantago asiatica mosaic virus (PlAMV) modulates host Ca2+ and ROS-associated signaling in Arabidopsis thaliana. Using live-cell imaging and the R-GECO1.2 Ca2+ sensor, we observed a rapid increase in cytoplasmic Ca2+ before the virus was detected, indicating that Ca2+ release occurs early in infection. Genetic analysis showed that GLR, CPK3, and CNGC, core components of Ca2+ signaling, limit PlAMV spread between cells, while the usual pattern-triggered immunity (PTI) co-receptors were not needed. This means that Ca2+-based antiviral restriction operates independently of PTI. With the plasma membrane-tethered and cytosolic HyPer7 biosensor, we found that ROS levels were lower inside infection foci in the inoculated leaves, but higher in nearby cells, respectively. The NADPH oxidases RBOHD and RBOHF, which produce ROS, slowed down the local viral propagation. The PM sphingolipid biosynthetic enzyme MOCA1 altered ROS patterns and reduced the viruss spread. Epistasis analysis revealed a functional interaction between RBOHD and MOCA1, suggesting that ROS signaling and plasma membrane sphingolipid homeostasis are interconnected in antiviral defense. Overall, our findings suggest that PlAMV triggers Ca2+ influx and ROS signaling at the plasma membrane, which induces sphingolipid reorganization and helps restrict the propagation of the virus. This study shows how Ca2+, ROS, and membrane sphingolipid signaling work together in plant antiviral immunity and points to possible ways to improve resistance to viruses.

plant biology↗

bioRxiv2026

Nanoscale regulation of ROS signaling at the plasma membrane tunes the plant response to osmotic stress

The spatiotemporal organization of proteins and lipids within membranes is crucial for ensuring proper cellular signaling. While the segregation of proteins and lipids into membrane nanodomains is well established, it remains unclear whether nanodomains can generate gradients of small diffusible molecules. In plants, reactive oxygen species (ROS), especially hydrogen peroxide (H2O2), act as a key signaling molecules in response to environmental stimuli such as osmotic stress. However, how extracellular H2O2 affects intracellular signaling has remained unknown. Here, we show that osmotic stimulation induces the formation of localized, H2O2-rich nano-environments at the cytoplasmic face of the plasma membrane (PM) in Arabidopsis root cells. Using a PM-tethered H2O2 biosensor, we found that these oxidized nanodomains arise from the clustering of RESPIRATORY BURST OXIDASE HOMOLOGs (RBOHs) and RHO OF PLANTS 6 (ROP6), in coordination with aquaporin-mediated H2O2 transport via the PLASMA MEMBRANE INTRINSIC PROTEIN2;7 (PIP2;7). These local redox hotspots at the PM create a feedforward loop in which H2O2 enhances ROP6 nanoclustering thereby amplifying ROS signaling. Disruption of H2O2 production or transport dampens both ROP6 clustering and anisotropic cell expansion, indicating a crucial role for spatially-confined redox signaling in regulating plant growth under osmotic stress. Our findings propose a model in which ROP6/RBOHD-F/PIP2;7 nanodomains function as discrete redox signaling units, redefining ROS signaling at the PM as a structured, signal-specific, and compartmentalized process.

cell biology↗

bioRxiv2025

Sphingolipid-driven interleaflet coupling orchestrates Rho-GTPase recruitment to nanodomains for signal activation in plants

Biological membranes are both laterally heterogeneous and asymmetrical across leaflets, yet how this asymmetry contributes to signal transduction remains unclear. Here we show that sphingolipid-driven interleaflet coupling coordinates nanodomain organization and Rho-GTPase activation in plants. Using molecular dynamics simulations, super-resolution and single-molecule imaging, quantitative genetics, and biochemistry, we find that very long acyl chain (VLCFA)-containing sphingolipids in the outer leaflet interdigitate with phosphatidylserine (PS) in the inner leaflet, forming a vertical molecular bridge that organizes PS into nanodomains. This coupling promotes recruitment and activation of the Rho-GTPase ROP6 in response to auxin, whereas disruption of VLCFA synthesis or sphingolipid composition disperses PS and ROP6 nanodomains, impairing cytoskeletal reorganization and directional growth. Our findings reveal interleaflet coupling as a fundamental organizing principle linking membrane asymmetry to signaling, providing a conceptual framework for spatial and temporal control of signal transduction across eukaryotic membranes.

plant biology↗

bioRxiv2025

Mechanisms controlling the plasma membrane targeting and the nanodomain organization of the plant SPFH protein HIR2

HIR2 is a plant-specific protein belonging to the superfamily of SPFH domain-containing proteins that were proposed to play scaffolding functions in membranes. HIR2 organizes in plasma membrane (PM) nanodomains that correspond to nanometric scale structures enriched in specific lipids and proteins acting as signaling/regulation hubs. So far, how PM nanodomains are formed and maintained in plant cells remains largely unknown. Combining state of the art microscopy techniques, we investigated the mechanisms governing the trafficking and the organization into nanodomains of Arabidopsis HIR2 protein. We revealed that the mono S-acylation of HIR2 either on C6 or on C7 was required for HIR2 targeting to the PM of Arabidopsis cells, independently of the conventional secretory pathway. Investigating the mechanisms implicated in the arrangement of HIR2 into nanodomains, we provided evidences that the lipid composition in sterols and very long chain fatty acids of the PM influenced HIR2 organization. HIR2 forms oligomers and we demonstrated here that the C-terminal part of HIR2 is required for self-assembly, similarly to animal SPFH proteins. Interestingly, we highlighted that the oligomerization of HIR2 is essential for its organization in nanodomains and to ensure HIR2 lateral stability in the PM. Overall, we propose that HIR2 nanodomain organization is a complex mechanism relying on different parameters including PM lipid composition and oligomerization. HIR proteins are involved in plant immunity. Here, we revealed that HIR2 nanodomain organization is required to boost the apoplastic ROS burst induced by the bacterial peptide flg22. One sentence summaryS-acylation and oligomerization control the plasma membrane targeting and the organization into nanodomains of the Arabidopsis SPFH-domain containing protein HIR2, respectively.

plant biology↗

bioRxiv2020

A plasma membrane nanoplatform ensures signal specificity during osmotic signaling in plants

In the course of their growth and development plants have to constantly perceive and react to their environment. This is achieved in cells, by the coordination of complex combinatorial signaling networks. However, how signal integration and specificity are achieved in this context is unknown. With a focus on the hyperosmotic stimulus, we use live super-resolution light imaging methods to demonstrate that a Rho GTPase, Rho-of-Plant 6 (ROP6), forms stimuli-dependant nanodomains within the PM. These nanodomains are necessary and sufficient to transduce production of reactive oxygen species (ROS),that act as secondary messengers and trigger several plant adaptive responses to osmotic constraints. Furthermore, ROP6 activation triggers the nanoclustering of two NADPH oxidases that subsequently generates ROS. ROP6 nanoclustering is also needed for cell surface auxin signaling, but short-time auxin treatment does not induce ROS accumulation. We show that auxin-induced ROP6 nanodomains, unlike osmotically-driven ROP6 clusters, do not recruit the NADPH oxidase, RBOHD. Together, our results suggest that Rho GTPase nano-partitioning at the PM ensure signal specificity downstream of independent stimuli.

plant biology↗

bioRxiv2018

In vivo phosphatidylserine variations steer Rho GTPase signaling in a cell-context dependent manner

AbstractRho GTPases are master regulators of cell signaling, but how they are regulated depending on the cellular context is unclear. Here, we show that the phospholipid phosphatidylserine acts as a developmentally-controlled lipid rheostat that tunes Rho GTPase signaling in Arabidopsis. Live super-resolution single molecule imaging revealed that RHO-OF-PLANT6 (ROP6) is stabilized by phosphatidylserine into plasma membrane (PM) nanodomains, which is required for auxin signaling. Furthermore, we uncovered that the PM phosphatidylserine content varies during plant root development and that the level of phosphatidylserine modulates the quantity of ROP6 nanoclusters induced by auxin and hence downstream signaling, including regulation of endocytosis and gravitropism. Our work reveals that variations in phosphatidylserine levels are a physiological process that may be leveraged to regulate small GTPase signaling during development.\n\nOne Sentence SummaryPhosphatidylserine acts as a developmentally-controlled lipid rheostat that regulates cellular auxin sensitivity and plant development.

plant biology↗