Over millions of years, plants have evolved sophisticated immune systems to fend off pathogens such as fungi and bacteria. At the heart of these defense mechanisms lies ubiquitin, a tiny protein that functions like a molecular tag—marking other proteins for recycling or destruction. These tags are then recognized by the proteasome, a cellular machine that breaks down unwanted or damaged proteins. But pathogens are constantly evolving, developing new ways to bypass plant immunity and cause disease.
For years, Dr. Beatriz Orosa has been investigating how plants regulate the strength and duration of their immune responses through a process called ubiquitination. Now, with the support of a prestigious European Research Council (ERC) grant, the CiQUS researcher will lead a new project that focuses on E3 ligases—enzymes that play a central role in determining which proteins get tagged with ubiquitin. “We want to understand how plants have refined their immune responses over evolutionary time by modifying proteins,” explains Dr. Orosa, “and use synthetic biology to strengthen their defense against pathogens they are still vulnerable to.”
The team will use barley and its fungal pathogen Puccinia hordei—commonly known as barley rust—as a model system. This disease causes reddish pustules on leaves and can lead to significant crop losses. The project will study the immune-activated E3 ligases in barley, as well as the molecular tricks used by the fungus to disarm the plant’s defenses. But the scope of the project goes further: the researchers aim to design synthetic E3 ligases that can switch on immune pathways on demand and target pathogen proteins that suppress plant immunity. The ultimate goal is to develop molecular tools to precisely and sustainably enhance disease resistance in crops.
Crop diseases are an increasingly urgent global issue, threatening food security and agricultural sustainability. It's estimated that pests and pathogens destroy up to 40% of crops each year. Enhancing natural plant immunity could reduce our dependence on chemical treatments while offering a more resilient and environmentally friendly approach. “I’ve always been fascinated by the way plants sense, anticipate and respond so quickly to environmental changes and pathogens,” says Dr. Orosa, who will carry out this five-year project at CiQUS, a center co-funded by the European Union through the Galicia FEDER Programme 2021–2027.
Roya de la cebada (Puccinia hordei) | Donald Groth
