title: Expression of Bradyrhizobium japonicum nodulation gene in Rhizobium fredii nod mutants.
abstract: The B. japonicum USDA 110 pLAFR1 gene library was transferred to Tn5-induced Rhizobium fredii USDA 191-4 Nod- mutants with helper plasmid pRK2013. SmR TcR transconjugants occurred with a frequency of 5 x 10(-4). The transconjugants were purified and used to inoculate germinated soybean seeds. Seven nodules were obtained in the nodulation experiment. The fast-growing Nod+ SmR TcR Rhizobium fredii strain was isolated from all nodules. Each isolate had acquired a new plasmid with a molecular mass of approximately 51 kb. This recombinant plasmid was transferred to E. coli HB101 by helper pRK2013 at a frequency of 1 x 10(-4). In addition to the vector fragment, all the recombinant plasmids gave 23 kb and 6.5 kb fragments on EcoRI digestion. A DNA-DNA hybridization test with a 32P-labelled nod gene probe (prepared from pRmSL26) confirmed that the 20 kb EcoRI-BamHI DNA fragment of the plasmids exhibited sequence homology with an R. meliloti nod gene probe.
authors.affiliation: Wuhan Institute of Virology, Academia Sinica.
authors.forename: L M
authors.initials: LM
authors.lastname: Zhou
authors.forename: T W
authors.initials: TW
authors.lastname: Huang
authors.forename: H Y
authors.initials: HY
authors.lastname: Gong
authors.forename: L F
authors.initials: LF
authors.lastname: Ning
authors.forename: Y H
authors.initials: YH
authors.lastname: Cen
mesh_terms: D015139:Blotting, Southern; D003001:Cloning, Molecular; D003227:Conjugation, Genetic; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D005798:Genes, Bacterial; D009154:Mutation; D009586:Nitrogen Fixation / Q000235:genetics*; D010957:Plasmids; D015183:Restriction Mapping; D012230:Rhizobiaceae / Q000235:genetics*; D012231:Rhizobium / Q000235:genetics*