Genetic stability, environmental safety and field adaptation assessment of transgenic rice with chicken Newcastle disease HN protein

Based on the previously verified head-to-tail dimer vaccine model, a dimer of the HN protein (defined as Osr2HN) expressed in rice endosperm was designed. In previous immunization experiments in chickens, immunization with two doses (0.5 µg, equivalent to 1/127 of a grain of rice) or a single dose (5 µg) provided complete protection. To advance the commercialization process of this product, in this study, we selected two transgenic rice strains (HN-1 and HN-2) and cultured them for three generations to evaluate their genetic stability, agronomic traits, and safety. Insertion site analysis showed that exogenous genes were stably integrated into nuclear chromosomes with no variants, as confirmed by PCR, qRT-PCR, and Western blotting. The transgenic strains exhibited germination rates, growth cycles, and 12 agronomic traits similar to those of the wild-type TP309, though HN-2 showed increased chalkiness. Pollen viability remained unchanged, and no transfer of the HN gene to weeds was detected. Field biodiversity analysis revealed no impact of the HN gene on pest and weed communities. These findings validate the transgenic rice’s genetic stability, agronomic adaptability, and environmental safety, providing critical data to support the acceleration of its commercialization as a plant-derived vaccine platform.