W. Tang et al., Regeneration of transgenic loblolly pine (Pinus taeda L.) from zygotic embryos transformed with Agrobacterium tumefaciens, PLANTA, 213(6), 2001, pp. 981-989
Embryos of 24 open-pollinated families of loblolly pine (Pinus teade L.) we
re used as explants to conduct in vitro regeneration. Then, Agrobacterium t
umefaciens strain GV3101 harboring the plasmid pPCV6NFHygGUSINT was used to
transform mature zygotic embryos of seven families of loblolly pine. The f
requency of transformation varied among families infected with A. tumefacie
ns. The highest frequency (100%) of transient fl-glucuronidase (GUS)-expres
sing embryos was obtained from family 11-1029 with over 300 blue spots per
embryo. Expression of the GUS reporter gene was observed in cotyledons, hyp
ocotyls, and radicles of co-cultivated mature zygotic embryos, as well as i
n callus and shoots derived from co-cultivated mature zygotic embryos. Nine
ty transgenic plants were regenerated from hygromycin-resistant callus deri
ved from families WO3, 8-1082 and 11-1029, and 19 transgenic plantlets were
established in soil. The presence of the GUS gene in the plant genome was
confirmed by polymerase chain reaction, Southern blot, and plant DNA/T-DNA
junction analysis. These results suggest that an efficient A. tumefaciens-m
ediated transformation protocol for stable integration of foreign genes int
o loblolly pine has been developed and that this transformation system coul
d be useful for future studies on transferring economically important genes
to loblolly pine.