Sequence of the iaa and ipt region of different Agrobacterium tumefaciens biotype III octopine strains: reconstruction of octopine Ti plasmid evolution.
The TA regions of biotype III octopine/cucumopine (OC) Ti plasmids are closely related to the TL region of the biotype I octopine Ti plasmids pTiAch5 and pTi15955. Sequence analysis shows that the limited and wide host range biotype III OC TA regions are derived from a common ancestor structure which lacked the 6a gene found in the biotype I octopine TL region. The TA region of the wide host range OC Ti plasmids has conserved most of the original TL-like structure. In most wide host range OC isolates the TA-iaaH gene is inactivated by the insertion of an IS866 element. However, the TA region of the wide host range isolate Hm1 carries an intact TA-iaaH gene. This gene encodes a biologically active product, as shown by root induction tests and indole-3-acetic acid measurements. The limited host range OC Ti plasmids pTiAB3 and pTiAg57 have shorter TA regions which are derived from a wide host range TA region. The AB3 type arose by an IS868-mediated, internal TA region deletion which removed the iaa genes and part of the ipt gene and left a copy of IS868 at the position of the deleted fragment. The pTiAB3 iaa/ipt deletion was followed by insertion of a second IS element, IS869, immediately 3' of the ipt gene. pTiAg57 underwent the same iaa-ipt deletion as pTiAB3, but lacks the IS868 and IS869 elements. Analysis of the various TA region structures provides a detailed insight into the evolution of the biotype III OC strains.
Paulus
F
F
Institut de Biologie Moléculaire des Plantes du C.N.R.S., Strasbourg, France.
Canaday
J
J
Vincent
F
F
Bonnard
G
G
Kares
C
C
Otten
L
L
D000595:Amino Acid Sequence; D001120:Arginine / Q000031:analogs & derivatives* / Q000378:metabolism; D001483:Base Sequence; D005075:Biological Evolution; D004926:Escherichia coli / Q000235:genetics; D005798:Genes, Bacterial; D005838:Genotype; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010957:Plasmids; D015183:Restriction Mapping; D012231:Rhizobium / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid
C005394:octopine; D001120:Arginine