Polyglutamate-loaded chitosan nanogels reprogram plant metabolism for increased growth and viral resistance

Asparagine synthetase B (AS-B) is essential for nitrogen metabolism, but its broader physiological functions remain poorly understood. Here we show that the evolutionarily conserved Nicotiana benthamiana NbAS-B confers expression-dependent antiviral resistance and promotes plant growth. Multi-omics analyses indicate that NbAS-B-mediated antiviral immunity relies on glutamate-induced activation of Ca²⁺ signaling through the receptor GLR3.3, whereas its growth-promoting effect results from photosynthetic reprogramming. Building on these insights, we develop polyglutamate-loaded chitosan nanogels (PGANPs) to artificially manipulate this pathway. These nanogels efficiently enter plant tissues and enable sustained in situ release of glutamate, thereby mimicking and amplifying NbAS-B signaling outputs. PGANPs provide long-lasting systemic antiviral immunity while concurrently enhancing plant growth, without incurring metabolic costs. Our work identifies NbAS-B as a dual-function regulator linking metabolic status to immune activation and establishes PGANPs as an eco-friendly, controllable, and durable nanobiotechnology for managing viral diseases in crops.