Physical and gene maps of Agrobacterium biovar 2 strains and their relationship to biovar 1 chromosomes.
Diverse types of genomic DNA organization have been found in Rhizobiaceae, especially among Agrobacterium species. Previous studies of Agrobacterium concentrated mainly on biovar 1 strains. Little attention has been given to biovar 2 strains. The biovar 2 genome consists of a large, circular chromosome and second megabase-sized replicon, as well as several plasmids. In this study two biovar 2 strains were analysed, A. rhizogenes (A. radiobacter) K84 and A. rhizogenes A4, by constructing physical maps of their chromosomes and mega-replicons. The maps revealed that in both strains their chromosomes consist of approximately 3.7 Mbp, while the mega-replicons are 2.6 Mbp circular DNAs. Gene mapping and comparative genomic analysis were performed based on the physical maps using Southern hybridization. It was found that rDNA, as well as analysed virulence and virulence-related genes, are present only on the chromosomes. The inter-chromosomal relationship between biovar 1 and biovar 2 strains was also analysed. Interestingly, there was a high similarity between the chromosomes of biovar 2 and the circular chromosomes of biovar 1, whereas similarity among the smaller megabase-sized replicons was restricted to each biovar. Based on these observations the possible relationship among large replicons in Agrobacterium biovars 1 and 2 is discussed.
Urbanczyk
Henryk
H
Laboratory of Plant Molecular Biology and Bioinformatics, Department of Biological Science, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.
Suzuki
Katsunori
K
Laboratory of Plant Molecular Biology and Bioinformatics, Department of Biological Science, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.
Yoshida
Kazuo
K
Laboratory of Plant Molecular Biology and Bioinformatics, Department of Biological Science, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.
Kondo
Katsuhiko
K
Laboratory of Plant Chromosome and Gene Stock, Department of Biological Science, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.
D002876:Chromosomes, Bacterial; D004275:DNA, Ribosomal / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D020161:Physical Chromosome Mapping; D012231:Rhizobium / Q000235:genetics* / Q000472:pathogenicity; D014774:Virulence / Q000235:genetics
D004275:DNA, Ribosomal