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 produ
ction showed a delay in the development of colour in the transgenic fr
uit. Northern analysis of steady-state RNA levels using strand-specifi
c probes indicated that fruit of the low-ethylene line had very low le
vels of ACC-oxidase sense-RNA, and high levels of antisense RNA. In ot
her lines, high levels of antisense RNA were not always associated wit
h a reduction in the levels of either sense-transcript or ethylene pro
duction. The successful reduction in ethylene production confirms the
usefulness of using tomato as a model system for testing specific ripe
ning-related genes from heterologous fruit species such as apple. Copy
right (C) 1997 Elsevier Science Ireland Ltd.