Tsuyoshi Isawa

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Nitrogen-fixing bacteria were isolated from the stems of wild and cultivated rice on a modified Rennie medium. Based on 16S ribosomal DNA (rDNA) sequences, the diazotrophic isolates were phylogenetically close to four genera: Herbaspirillum, Ideonella, Enterobacter, and Azospirillum. Phenotypic properties and signature sequences of 16S rDNA indicated that(More)
We determined the nucleotide sequence of the entire genome of a diazotrophic endophyte, Azospirillum sp. B510. Strain B510 is an endophytic bacterium isolated from stems of rice plants (Oryza sativa cv. Nipponbare). The genome of B510 consisted of a single chromosome (3,311,395 bp) and six plasmids, designated as pAB510a (1,455,109 bp), pAB510b (723,779(More)
We previously reported that extra-slow-growing Bradyrhizobium japonicum isolates obtained from three field sites in Japan, designated as HRS (highly reiterated sequence-possessing) strains, have high copy numbers of the insertion sequences RSK and RSL. When strain collections in the USA, Japan, Korea, Thailand and China were examined by Southern(More)
In a survey of DNA fingerprints of indigenous Bradyrhizobium japonicum with the species-specific repeated sequences RS alpha and RS beta, 21 isolates from three field sites showed numerous RS-specific hybridization bands. The isolates were designated highly reiterated sequence-possessing (HRS) isolates, and their DNA hybridization profiles were easily(More)
Agriculturally important grasses contain numerous diazotrophic bacteria, the interactions of which are speculated to have some other benefits to the host plants. In this study, we analyzed the effects of a bacterial endophyte, Azospirillum sp. B510, on disease resistance in host rice plants. Rice plants (Oryza sativa cv. Nipponbare) were inoculated with(More)
The expression of nitrogenase genes of Herbaspirillum sp. B501 associated in shoot (leaf and stem) of wild rice, Oryza officinalis, was studied by means of reverse transcription-PCR (RT-PCR) targeted at the nifH gene. RT-PCR analyses indicate that nifH transcript was detected exclusively from nitrogen-fixing cells of gfp-tagged strain B501gfp1 in both(More)
From Bradyrhizobium japonicum highly reiterated sequence-possessing (HRS) strains indigenous to Niigata and Tokachi in Japan with high copy numbers of the repeated sequences RSalpha and RSbeta (K. Minamisawa, T. Isawa, Y. Nakatsuka, and N. Ichikawa, Appl. Environ. Microbiol. 64:1845-1851, 1998), several insertion sequence (IS)-like elements were isolated by(More)
Inoculation experiments with the endophytic bacterium Azospirillum sp. strain B510, an isolate from surface-sterilized stems of field-grown rice, were conducted in pots in a greenhouse, and in paddy fields in Hokkaido, Japan. B510 significantly enhanced the growth of newly generated leaves and shoot biomass under greenhouse conditions. When rice seedlings(More)
Extra-slow-growing bradyrhizobia from root nodules of field-grown soybeans harbor abundant insertion sequences (ISs) and are termed highly reiterated sequence-possessing (HRS) strains. We analyzed the genome organization of HRS strains with the focus on IS distribution and symbiosis island structure. Using pulsed-field gel electrophoresis, we consistently(More)