1. Wheat root colonization and nitrogenase activity by Azospirillum isolates from crop plants in Korea.
- Author
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Kim C, Kecskés ML, Deaker RJ, Gilchrist K, New PB, Kennedy IR, Kim S, and Sa T
- Subjects
- Acetylene metabolism, Artificial Gene Fusion, Azospirillum classification, Azospirillum isolation & purification, Bacterial Typing Techniques, DNA, Bacterial chemistry, DNA, Bacterial genetics, DNA, Ribosomal chemistry, DNA, Ribosomal genetics, Enterobacter classification, Enterobacter growth & development, Enterobacter isolation & purification, Gene Expression, Genes, Reporter, Korea, Oxidation-Reduction, Sequence Analysis, DNA, beta-Galactosidase analysis, beta-Galactosidase genetics, Azospirillum enzymology, Azospirillum growth & development, Crops, Agricultural microbiology, Nitrogenase metabolism, Plant Roots microbiology, Triticum microbiology
- Abstract
Nitrogen-fixing bacteria were isolated from the rhizosphere of different crops of Korea. A total of 16 isolates were selected and characterized. Thirteen of the isolates produced characteristics similar to those of the reference strains of Azospirillum, and the remaining 3 isolates were found to be Enterobacter spp. The isolates could be categorized into 3 groups based on their ARDRA patterns, and the first 2 groups comprised Azospirillum brasilense and Azospirillum lipoferum. The acetylene reduction activity (ARA) of these isolates was determined for free cultures and in association with wheat roots. There was no correlation between pure culture and plant-associated nitrogenase activity of the different strains. The isolates that showed higher nitrogenase activities in association with wheat roots in each group were selected and sequenced. Isolates of Azospirillum brasilense CW301, Azospirillum brasilense CW903, and Azospirillum lipoferum CW1503 were selected to study colonization in association with wheat roots. We observed higher expression of beta-galactosidase activity in A. brasilense strains than in A. lipoferum strains, which could be attributed to their higher population in association with wheat roots. All strains tested colonized and exhibited the strongest beta-galactosidase activity at the sites of lateral roots emergence.
- Published
- 2005
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