ViROSCa · Deciphering the roles of reactive oxygen species and calcium during viral infection in Arabidopsis

Deciphering the roles of reactive oxygen species and calcium during viral infection in Arabidopsis

Viral diseases are a major and growing threat to global food security, responsible for severe crop losses and rising pesticide use. One such emerging pathogen is Plantago asiatica mosaic virus (PlAMV), a potexvirus capable of infecting a wide range of hosts and spreading rapidly between plant cells. Once a virus enters a leaf, it moves from cell to cell through tiny channels called plasmodesmata, eventually reaching the whole plant. How plants detect viral invasion at this early stage — and how viruses overcome these defenses — remains poorly understood. The ViROSCa project addresses this knowledge gap by investigating how PlAMV infection affects two critical host defense signals: calcium (Ca²⁺) and reactive oxygen species (ROS). These signals act as early messengers in plant immunity, triggering cellular responses that can contain or slow down pathogen spread. The project’s main objective is to identify how these signals are activated and coordinated at the cell membrane during infection, which genes are involved, and how this knowledge can be used to support the development of more virus-resistant and resilient crops. This research contributes directly to European Union priorities, including the Green Deal and Farm to Fork strategies, by providing scientific knowledge that can help reduce dependence on chemical pesticides and enable more sustainable agricultural practices. Work performed and main achievements The project combined transcriptomic analysis, live-cell imaging, and genetic approaches to study early host responses to PlAMV infection in Arabidopsis thaliana. • Gene expression profiling: Infection by PlAMV triggered strong activation of membrane-associated genes involved in calcium influx and ROS metabolism. • Calcium imaging: Using a fluorescent calcium biosensor (R-GECO1), the team visualized a rapid wave of calcium release starting at the infection site and spreading to neighboring cells. This calcium signal occurred before the virus accumulated, indicating it is an early step in infection. • Functional genetics: Mutants lacking GLR3, CNGC, or CPK3 allowed the virus to spread faster between cells, confirming that these genes are key components of the antiviral response. • ROS imaging: A second biosensor (HyPer7-kRas) revealed a striking spatial pattern in ROS accumulation: ROS were suppressed in infected cells but increased in surrounding cells, creating a defensive perimeter. This defense pattern required the genes RBOHD, CPK3, and MOCA1. • Signaling hierarchy: RBOHD-derived ROS production acted upstream of MOCA1-mediated lipid remodeling, and MOCA1 function was dominant over CPK3. This revealed a hierarchical membrane signaling cascade coordinating early antiviral defense. • Systemic control: RBOHD was essential not only for local defense but also for preventing the virus from spreading through the whole plant, while MOCA1 played a more local role at the membrane. • PTI independence: Core pattern-triggered immunity (PTI) components such as SERK co-receptors and HIR proteins were not required for PlAMV restriction, revealing a distinct, PTI-independent signaling pathway. This integrated approach uncovered how viruses interact with host membrane signaling and how plants activate targeted defenses at infection sites. Progress beyond the state of the art and expected results Before this project, the molecular events linking calcium influx, ROS production, and viral movement were not clearly defined. ViROSCa provides the first detailed picture of this interaction: • It identified key host genes (GLR3, CNGC, CPK3, RBOHD/F, MOCA1) that control early defense signaling and viral spread. • It demonstrated that Ca²⁺ elevation is an early infection signal, preceding virus movement. • It revealed a spatial ROS defense gradient around infected cells and its genetic dependencies. • It mapped the signaling hierarchy linking Ca²⁺ channels, ROS-producing enzymes, and membrane lipid remodeling. • It showed that this defense mechanism functions independently of classical PTI pathways. These discoveries set the stage for new strategies to enhance natural antiviral defenses in crops through breeding or biotechnological approaches. They also provide new biosensor tools and imaging methods that can be adopted by other research groups and industries. Societal and economic impact Plant viruses are a major driver of crop loss and pesticide use worldwide. By uncovering how early membrane signaling restricts viral spread, ViROSCa provides a biological alternative to chemical control. This work directly supports: • EU Green Deal and Farm to Fork Strategy, by reducing reliance on pesticides and promoting resilient agriculture. • EU Plant Health Regulations, through identifying new genetic markers for resistance. • Horizon Europe goals (Cluster 6), by linking fundamental research with applied agricultural innovation. The project also trained a highly skilled researcher in advanced imaging and molecular techniques, strengthened international collaborations (France–UK), and generated tools and knowledge that will remain available to the scientific community. In the longer term, these results may contribute to virus-resistant crops, improved food security, and more sustainable farming systems in Europe and globally.

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз