title: A locus encoding host range is linked to the common nodulation genes of Bradyrhizobium japonicum.
abstract: By using cloned Rhizobium meliloti, Rhizobium leguminosarum, and Rhizobium sp. strain MPIK3030 nodulation (nod) genes as hybridization probes, homologous regions were detected in the slow-growing soybean symbiont Bradyrhizobium japonicum USDA 110. These regions were found to cluster within a 25-kilobase (kb) region. Specific nod probes from R. meliloti were used to identify nodA-, nodB-, nodC-, and nodD-like sequences clustered on two adjacent HindIII restriction fragments of 3.9 and 5.6 kb. A 785-base-pair sequence was identified between nodD and nodABC. This sequence contained an open reading frame of 420 base pairs and was oriented in the same direction as nodABC. A specific nod probe from R. leguminosarum was used to identify nodIJ-like sequences which were also contained within the 5.6-kb HindIII fragment. A nod probe from Rhizobium sp. strain MPIK3030 was used to identify hsn (host specificity)-like sequences essential for the nodulation of siratro (Macroptilium atropurpureum) on a 3.3-kb HindIII fragment downstream of nodIJ. A transposon Tn5 insertion within this region prevented the nodulation of siratro, but caused little or no delay in the nodulation of soybean (Glycine max).
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D004269:DNA, Bacterial / Q000235:genetics; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D009693:Nucleic Acid Hybridization; D011401:Promoter Regions, Genetic; D012230:Rhizobiaceae / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity; D013559:Symbiosis
chemical_list: D004269:DNA, Bacterial