The Agrobacterium rhizogenes T-DNA oncogene rolD under the control of
its own 5' regulatory region was transferred to day-neutral tobacco pl
ants. The main trait induced by roll) in transgenic plants is a striki
ng precocity in newer setting and a strong enhancement of the flowerin
g potential. In rolD plants, early flowering is followed by the very r
apid growth of numerous lateral inflorescences. The analysis of severa
l morphological and histological parameters suggests that some charact
eristic morphological abnormalities observed in rolD plants can be acc
ounted for by their early reproductive phase transition and points to
the involvement in the transition of a greater portion of the plant bo
dy than is the case for untransformed tobacco. The in vitro morphogeni
c potential of tissues from rolD plants was also tested. Superficial t
hin cell layer explants from rolD plants show an earlier and much enha
nced newer organogenesis, compared to controls, both on flowering and
on hormone-free medium. (C) 1996 Academic Press, Inc.