Researchers at the CSIR-Centre for Cellular and Molecular Biology (CCMB) have identified a key mechanism through which plants defend themselves against viral infections, by using sticky, liquid-like protein droplets that trap and disable invading viruses.

The discovery has significant implications as it could pave the way for developing crop varieties with stronger natural resistance to viral diseases. And by enhancing or mimicking these protein-based traps, scientists may be able to engineer more resilient plants, said an official release on Wednesday.

The study, led by Mandar V. Deshmukh and published in the Journal of the American Chemical Society (JACS), revealed how these protein droplets form and function at a molecular level, offering fresh insight into plant immunity.

Many viruses carry their genetic material in the form of double-stranded RNA. When plants are infected, they ramp up the production of specialised RNA-binding proteins that can recognise this viral genetic material. Some of these proteins attach to sites known as ‘Viral Replication Complexes to stall the virus’ ability to copy itself to prevent the spread within the plant.

Until now, scientists believed these RNA-binding proteins worked in a simple “lock-and-key” manner binding directly to viral RNA. However, using advanced tools such as Nuclear Magnetic Resonance (NMR) spectroscopy, fluorescence microscopy, and molecular dynamics simulations, the CCMB team discovered a far more dynamic process.

Researchers found that these proteins have a unique structural fold with charged surfaces that create “sticky” patches. Positively charged regions attract negatively charged ones, allowing the proteins to cluster together into an interconnected network. This network forms dense, gel-like droplets that can trap viral RNA. “These proteins act like molecular glue,” said Jaydeep Paul, the study’s first author.

Plant cells effectively trap viral RNA through these droplets to prevent replication. These droplets or ‘biomolecular condensates’, are reshaping scientists’ understanding of how cells function. “We now see cells as a dynamic environment where membrane-less structures can form and dissolve like oil droplets in water”, said Mr.Deshmukh.

The findings could also have relevance for human health. Understanding how these sticky protein networks work could help researchers develop strategies to dissolve harmful protein clumps linked to neurodegenerative diseases or disrupt protective barriers around tumours. Ultimately, this knowledge could help new drugs design that target and manipulate these molecular interactions with precision, the release added.