Translocation of green fluorescent protein in homo- and hetero-transgrafted plants

Transgrafting, a technique involving the use of genetically modified (GM) plants as grafting partners with non-genetically modified (non-GM) crops, presents non-GM edible harvests from transgrafted crops, often considered as non-GM products. However, the classification of the non-GM portions from transgrafted crops as non-GM foods remains uncertain, therefore it is critical to investigate the potential translocation of substances from GM portions to non-GM edible portions in transgrafted plants. In this study, we explored the translocation of exogenous proteins (luciferase and green fluorescent protein) in model transgrafted plants consisting of GM plant rootstocks and non-GM tomato scions. Our results suggest that exogenous proteins accumulated in the stem tissues of non-GM tomato scions in all cases investigated. The levels and patterns of exogenous protein accumulation in the non-GM tomato stem tissues varied among the individual transgrafted plants and rootstock plant species used. However, exogenous proteins were not detected in the fruits, the edible part of the tomato, and in mature leaves in non-GM tomato scions under the current experimental conditions. Our results provide basic knowledge for understanding exogenous protein translocation in transgrafted plants.