Rice stripe virus exploits the miR159a.2-OsGTL1 module to manipulate growth-defense trade-offs.

Balancing growth and defense is critical for plant fitness and crop productivity, yet how viruses manipulate this trade-off remains unclear. Here, we identified the trihelix transcription factor Oryza sativa GT2-like 1 (OsGTL1) as a central regulator of the growth-defense trade-off in rice (Oryza sativa L.). Loss-of-function osgtl1 mutants displayed increased grain size but heightened susceptibility to rice stripe virus (RSV). We showed that miR159a.2 directly targets OsGTL1, and disrupting the miRNA binding site abolished its repression. RSV infection strongly induced miR159a.2, resulting in reduced OsGTL1 levels; rice grassy stunt virus elicited a similar response, whereas other rice viruses did not. These findings reveal that RSV hijacks a miRNA-transcription factor regulatory module to weaken immunity while redirecting resources toward growth, thereby manipulating the growth-defense trade-off. Our study identifies the miR159a.2-OsGTL1 node as a pathogen-sensitive hub with potential for molecular breeding strategies that optimize yield and disease resistance.