Tobacco rattle virus triggers local defense and systemically coordinates taxoid biosynthesis in Taxus baccata revealed by integrated metabolic analysis.

The clinical demand for paclitaxel necessitates novel strategies to enhance its production. While recent breakthroughs have elucidated the complete biosynthetic pathway in heterologous hosts, optimizing production within the native Taxus plant remains crucial. Here, we investigated the unexplored potential of using Tobacco rattle virus (TRV) as a controlled biotic elicitor in Taxus baccata seedlings. Using hydroponics and agroinfiltration, we found that TRV did not systemically infect or silence genes but triggered a localized hypersensitive response. Despite this, TRV significantly increased paclitaxel, baccatin III, and 10-deacetylbaccatin III levels in shoots, with the response depending on the infiltration method. Machine learning revealed exceptionally strong positive correlations among shoot taxoids (r > 0.94) and identified baccatin III levels as the primary predictor of paclitaxel yield. Metabolic flux analysis quantified a preferential enhancement of early pathway steps and revealed a relative bottleneck in the final conversion to paclitaxel. These results demonstrate that TRV acts as a potent, growth-neutral biotic elicitor in T. baccata, where local defense couples with systemic metabolic reprogramming. Our integrated analysis establishes a novel virus-mediated strategy to complement pathway-engineering approaches for sustainable taxane production.