Symbiotic mutants of Rhizobium meliloti that uncouple plant from bacterial differentiation.
Spontaneous mutants at a new symbiotic locus in Rhizobium meliloti SU47 are resistant to several phages and are conditionally insensitive to a monoclonal antibody to the bacterial surface, apparently because they are deficient in a wild-type exopolysaccharide. On alfalfa, the mutants do not curl root hairs, but penetrate the epidermis directly, forming nodules that contain no visible infection threads or "bacteroids," have a few bacteria in superficial intercellular spaces only and not within the nodule cells, and fail to fix nitrogen (Fix-). Evidently, infection threads are not essential for cell proliferation and nodule formation, which are here induced by a bacterial signal at a distance and uncoupled from the bacterial differentiation that normally goes on as well.
Finan
T M
TM
Hirsch
A M
AM
Leigh
J A
JA
Johansen
E
E
Kuldau
G A
GA
Deegan
S
S
Walker
G C
GC
Signer
E R
ER
D000911:Antibodies, Monoclonal / Q000276:immunology; D001435:Bacteriophages / Q000502:physiology; D004251:DNA Transposable Elements; D005798:Genes, Bacterial; D000455:Medicago sativa; D009154:Mutation; D009584:Nitrogen / Q000378:metabolism; D010944:Plants / Q000378:metabolism / Q000382:microbiology*; D011135:Polysaccharides, Bacterial / Q000235:genetics; D012231:Rhizobium / Q000235:genetics* / Q000276:immunology; D013559:Symbiosis
D000911:Antibodies, Monoclonal; D004251:DNA Transposable Elements; D011135:Polysaccharides, Bacterial; D009584:Nitrogen