Prabu Gnanasekaran (Guest Speaker from WSU)

Insights from Diverse Plant Virus Systems: Mechanisms and Management

Zoom Recording

About the Presenter

Prabu Gnanasekaran is a Research Associate working with Prof. Hanu Pappu in the Department of Plant Pathology at Washington State University. He earned his Ph.D. in Life Sciences with a specialization in Molecular Plant Virology from Jawaharlal Nehru University, India, and subsequently pursued postdoctoral research at Washington State University. Dr. Prabu’s research focuses on the molecular and biochemical mechanisms underlying plant–virus interactions, with particular emphasis on economically important plant viruses affecting horticultural and agricultural crops. His work spans studying viral protein function, host defense responses, resistance-breaking mechanisms, and virus-induced alterations of host metabolism. He has extensive experience with molecular, proteomic, and cell biology approaches to study viral pathogenesis. In addition to fundamental research, Dr.

Prabu is leading the Dahlia Resource Center activities at WSU, including the developing diagnostic tools, managing diagnostics, establishing virus elimination tissue culture pipeline and maintaining clean stock of popular dahlia cultivars.

Abstract

Viruses use diverse strategies that include disrupting host physiology and development, and defense pathways to cause disease. My research focus has been on gaining insights into host-virus interactions of diverse DNA and RNA viruses that include caulimoviruses, geminiviruses, potato virus Y (PVY), tomato spotted wilt virus, and viroids. By combining molecular, biochemical, and genomic approaches, my research has provided insights into how different plant viruses manipulate host cellular processes to promote infection and disease development. Also, using the knowledge gained from the molecular studies, I developed molecular diagnostic tools for reducing the impact of these viruses.

Geminiviruses cause some of the most economically damaging diseases in food, feed, and fiber crops in tropical as well as subtropical regions of the world. Geminivirus–betasatellite complex is an important model for understanding DNA virus pathogenicity and host – virus interactions. I showed that the betasatellite-encoded pathogenicity determinant βC1 targets chloroplast function resulting in vein clearing, and impaired photosynthesis. βC1 interacts with chloroplast-associated host factors and viral replication proteins to modulate host defense responses and helper virus replication leading to the establishment of virus infection.

In case of economically important RNA viruses, PVY is a constraint to potato production here in WA and other potato producing regions of the world. I showed that PVY exploits host hormone and metabolic pathways: PVY-coded NIa-pro protein was shown to stabilize indole-3-acetic acid–amido synthetase to alter auxin homeostasis and enhance disease development, while the PVY coat protein interacts with cytosolic phosphoglucomutase to reprogram host primary metabolism.

Dahlia is a high value flower, and viruses are recognized as a major constraint by dahlia stakeholders. A nationwide survey and testing of more than 4k samples provided a better understanding of the nature and identify of viruses that affect dahlias. Two caulimoviruses, dahlia mosaic virus and dahlia common mosaic virus were found to be widespread in dahlias. By comparative genomic analyses, I resolved the taxonomic ambiguity by demonstrating that these two are variants of a single species, with direct implications for diagnostics and disease management. A meristem tissue culture-based pipeline was established to produce virus-free dahlias with a goal to supply virus-free materials to stakeholders.

To address emerging phytosanitary challenges, a rapid, sensitive, and field-deployable CRISPR/Cas13-based SHERLOCK assay was developed for detecting quarantine-significant pospiviroids in tomato and pepper. Together, these studies integrate mechanistic understanding of virus-host interactions with practical diagnostic and management tools, highlighting how insights from diverse plant virus systems can advance sustainable disease