Identification of a Rhizobium meliloti pSym2011 region controlling the host specificity of root hair curling and nodulation.
In Rhizobium meliloti 2011 nodulation genes (nod) required to nodulate specifically alfalfa are located on a pSym megaplasmid. Nod- derivatives carrying large pSym deletions were isolated. By complementation of these strains with in vivo- and in vitro-constructed episomes containing pSym of sequences and introduction of these episomes into Agrobacterium tumefaciens, we show (i) that from a region of pSym of about 360 kilobases, genes required for specific alfalfa nodulation are clustered in a DNA fragment of less than 30 kilobases and (ii) that a nod region located between nifHDK and the common nod genes is absolutely required for alfalfa nodulation and controls the specificity of root hair curling and nodule organogenesis initiation.
D002872:Chromosome Deletion; D004591:Electrophoresis, Polyacrylamide Gel; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D008854:Microscopy, Electron; D009154:Mutation; D009586:Nitrogen Fixation; D010944:Plants; D010957:Plasmids; D012231:Rhizobium / Q000235:genetics*; D013559:Symbiosis