Antisense apple ACC-oxidase RNA reduces ethylene production in transgenic tomato fruit

Transgenic tomato (Lycopersicon esculentum) plants were produced which expressed antisense copies of an apple fruit ACC-oxidase RNA. In the fruit of the primary transformants, ethylene production was reduced by over 95% in one of the lines assessed, and to a lesser extent in the other lines. The line showing the greatest reduction in ethylene production showed a delay in the development of colour in the transgenic fruit. Northern analysis of steady-state RNA levels using strand-specific probes indicated that fruit of the low-ethylene line had very low levels of ACC-oxidase sense-RNA, and high levels of antisense RNA. In other lines, high levels of antisense RNA were not always associated with a reduction in the levels of either sense-transcript or ethylene production. The successful reduction in ethylene production confirms the usefulness of using tomato as a model system for testing specific ripening-related genes from heterologous fruit species such as apple.