An Endogenous, Flavor-Enhancing TRV/Agrobacterium System for Edible Tomato Fruits with the Sweet Protein Thaumatin II

The rise in diabetes and obesity worldwide has created an urgent demand for low-sugar, nutrient-dense foods with appealing flavors. This study established an endogenous and “rapid validation–stable production” platform to enhance the flavor of edible tomato fruits by integrating two key technologies in the MicroTom cherry tomato: (1) TRV viral vector-mediated transient expression and (2) Agrobacterium-mediated stable genetic transformation. We employed the human sweet taste receptor TAS1R2 for in vitro functional validation and objectively demonstrated that tomato-derived recombinant thaumatin II exhibits receptor-binding activity equivalent to that of the native protein, overcoming the limitations of traditional sensory evaluation. Non-targeted metabolomic analysis (covering 1236 metabolites) confirmed that thaumatin II expression did not significantly alter the profiles of sugars, organic acids, or key flavor compounds in tomato fruits. This provides safety data supporting the development of “ready-to-eat sugar-substitute fruits.” Our strategy offers a solution and theoretical technical support for the development of low-sugar, high-nutrient foods.