Functional and biochemical characterization of a novel geminivirus-encoded secreted peptide recognized by the host plant

• Applicant: Dr. Laura Medina Puche, Ph.D.
• Subject Area: Plant Breeding and Plant Pathology ; Virology
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 571857558

Viruses are small infectious agents that need to hijack the cellular machinery of their host to multiply and spread. The plant-infecting geminiviruses cause serious diseases in crops and have a significant impact on agriculture worldwide. Despite their small size and limited armoury, geminiviruses have evolved sophisticated strategies to manipulate plant cells and suppress their immune defences. Understanding how they achieve this can help us find better ways to protect crops from infection. This project focuses on a specific geminivirus called tomato yellow leaf curl virus (TYLCV), which severely affects tomato production. We study a viral protein called C4 that helps the virus to suppress plant defence mechanisms. Interestingly, this protein can move between different parts of the plant cell depending on whether the plant has activated its defences. However, how the virus controls this movement was unknown. In our recent research, we discovered a previously unknown small gene hidden in the virus's genome that encodes a short peptide, which we named PVG. This peptide is secreted outside the plant cell, into the space between cells (the apoplast), and appears to act as a signal to the plant, potentially mimicking a natural danger signal. Remarkably, this small peptide is both necessary and sufficient to trigger the movement of the C4 protein inside the cell — a key step in how the virus evades plant defences -, and is essential for the viral infection. Our project aims to understand how this viral peptide functions: How is it produced during infection? How is it perceived by the plant? What responses does it trigger? And how does it help the virus to spread and cause disease? To answer these questions, we will use a combination of molecular biology, plant genetics, microscopy, and biochemical methods. This research will not only provide fundamental insights into how geminiviruses interact with their host plants but may also uncover a previously unknown mechanism of viral recognition in plants. In the long term, our findings could help develop new strategies to protect crops by blocking viral signals or enhancing plant perception of infection.

• DFG Programme: Research Grants
• Co-Investigator: Professorin Rosa Lozano-Durán, Ph.D.