The non-conserved region of cucumopine-type Agrobacterium rhizogenes T-DNA is responsible for hairy root induction.
The T-DNA regions of three strains of Ri plasmids 1855, 8196, 2659 (agropine, mannopine and cucumopine type respectively) share two highly conserved regions flanking a non-homologous central part. We have cloned segments of the cucumopine Ri plasmid 2659 T-DNA in the binary vector system Bin 19 and infected carrot discs with recombinant Agrobacterium strains. We show here that the central non-conserved region is crucial in hairy root induction as it is sufficient to induce rooting on the apical (auxin-rich) surface of carrot discs; in order to observe rooting on the basal (auxin-depleted) side of the discs, a longer T-DNA fragment, also encompassing part of the right conserved region, had to be utilized in conjunction with a Agrobacterium strain carrying aux genes. Differences of growth properties in culture are exhibited by roots transformed with different fragments of pRi 2659 T-DNA, although all transformed roots show the plagiotropic behaviour typical of hairy roots.
Failla
M C
MC
Dip. Genetica e Biologia Molecolare, Università La Sapienza, Roma, Italy.
Maimone
F
F
De Paolis
A
A
Costantino
P
P
Cardarelli
M
M
D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics; D006838:Hydrocarbons; D007093:Imidazoles; D010935:Plant Diseases; D010944:Plants / Q000382:microbiology; D010957:Plasmids; D011725:Pyridines; D015183:Restriction Mapping; D012231:Rhizobium / Q000235:genetics*
D004269:DNA, Bacterial; D006838:Hydrocarbons; D007093:Imidazoles; D011725:Pyridines; C036483:T-DNA; C082688:cucumopine