Plant Immunity and Host Defence

Visit the ViroiDoc YouTube channel to watch a featured video lecture on how plants defend themselves against pathogens and pests by Professor Purificación Lisón from the Valencia Polytechnic University.

As sessile organisms, plants cannot escape stress and instead rely on sophisticated local and systemic defense mechanisms.

Three major systemic strategies are highlighted:

• Wound-Induced Resistance (WIR): Activated by insect feeding or tissue damage, it depends on jasmonic acid (JA) and ethylene signaling. This leads to the production of proteinase inhibitors and other defense compounds that limit herbivore attack.
• Systemic Acquired Resistance (SAR): A broad, long-lasting immune state triggered by biotrophic pathogens. It is mediated by salicylic acid (SA) and the expression of pathogenesis-related (PR) genes, ensuring protection in distant, uninfected tissues.
• Induced Systemic Resistance (ISR): Stimulated by beneficial soil microbes, ISR primes plants through JA/ethylene pathways, enhancing resilience against diverse pathogens.

In addition, the presentation emphasizes RNA silencing as a central antiviral mechanism. Small RNAs (siRNAs, miRNAs) direct the degradation of viral RNAs, providing plants with specific and heritable antiviral immunity. Recent findings in viroid research demonstrate the importance of SA signaling, modulation of ethylene, γ-aminobutyric acid (GABA) accumulation, and autophagy regulation in reducing disease severity and improving tolerance.

Together, these mechanisms illustrate the remarkable capacity of plants to integrate hormone signaling, systemic communication, and RNA-based defenses. Understanding and exploiting these natural processes opens the door to sustainable crop protection strategies, reducing reliance on chemical pesticides.

This research underlines the potential of systemic resistance and RNA silencing to shape future solutions for resilient agriculture and improved management of virus and viroid-related diseases.

Curious to learn more?

Visit the ViroiDoc YouTube channel to watch a featured video lecture by Prof. Purificación Lisón, recorded in September 2025 during the ViroiDoc Days of the EU-funded ViroiDoc project's training activities.

Purificación Lisón is an Associate Professor at the UPV and researcher at the Institute for Plant Molecular and Cell Biology (IBMCP). Her research focuses on viroid pathogenesis and the role of plant metabolites that accumulate under biotic stress.

Purificación Lisón also serves as the supervisor for Doctoral Candidate (DC6) who will work on the individual research project “Development of novel antiviroidal strategies: towards drug discovery" at the UPV.

Explore more content on viroid research by visiting ViroiDoc YouTube channel.