• Korean Journal of Microbiology
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• v.27 no.2
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• pp.92-97
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• 1989

the vector, pGUR19, for Rhizobium gene manipulation, was constructed by combining the replication and mobilization function of indigenous multicopy plasmid from Acacia(Robinia pseudoacacia L.) Rhizobia sp86 with E. coli cloning vehicle, pBR322. The vector could be efficiently mobilized by RP4 tra function incorporated into chromosome of E. coli named SM10 and efficiently transferred to various gram negative hosts including Rhizobium and Afrobacterium by transformation. Mobilization frequency of the constructed vector was ranged from $1.2\times 10^{-2}$ (E.coli HB 101) to $4.6\times 10^{-4}$ (A. tumefaciens 15955) and transformation frequency was ranged from $5.4\times 10^{-7}$(E. coli HB101) to $1.2\times 10^{-10}$ (A. tumefaciens 15955). The vector, pGUR19, was stably replicated and maintained in a variety of Rhizobium and Agrobacterium.

• Korean Journal of Soil Science and Fertilizer
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• v.12 no.1
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• pp.43-46
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• 1979

Curing the studies on the mechanism of the nodule formation and the infection of rhizobia using the continously cultured plant cell tissues, it was found that some calluses possess high nitrogen fixation activity. This experiment was conducted to know the differences among the calluses and the Rhizobia. The results obtained were as follows; 1) In a single inoculation the nitrogenase activity of soybean cell cultures-rhizobium was moderately higher than non-leguminous cell cultures, however, in the mixing inoculation that was reversely found. 2) Host factor, which was characteristics for the nodule formation and the nitrogenase activity, was not appeared generally in the plant cell cultures except for Kuamusume and Toyozuzu in soybean, and Datura in non-leguminous cell cultures. 3) In the 012 rhizoblium cultured on soybean cell cultures and in the 010, 023 and 024 rhizobia cultured on non-leguminous cell cultures the nitrogenase activity higher than the others.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.26 no.2
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• pp.192-197
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• 1981

Alfalfa (Medicago sativa L. cv. Luna) seeded in agar was inoculated with two strains of Rhizobium meliloti isolated from root nodules of alfalfa for assessment of nodulation. The seedling growth after six weeks was remarkably increased by adding each rhizobia strains into agar media and also by nitrate application (70ug N/ml), but there was no significant difference among them. Nodulations started one week after inoculation and increased its numbers and sizes as seedling grew. Therefore, the two strains isolated from alfalfa root were concluded to be effective strains. For determining seed inoculation method the same cultivar was inoculated with both rhizobia strains using different inoculation methods such as broth-vacuum, peat-adhesive, peat & lime pelleting. They were seeded in pots of river sand and supplied with culture solution excluded nitrogen. The peat & lime pelleting was recognized the best method in both of nodulation and seedling growth after eight weeks growth. There were significant correlations between the weight of nodules and the shoot or root dry weight of alfalfa in both rhizobia strains.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.2
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• pp.157-165
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• 1986

This experiment was conducted to find out the some physiological characteristics and nitrogen fixation activities under free-living conditions of indigenous rhizobia isolated from soybean-cultivated (30 fields) and un-cultivated (30 fields) soil. The results were summerized as follows: 1. In free-living condition, only 12.8% and 6.4% of the indigenous rhizobia isolated from soybean cultivated (133 strains) and un-cultivated (125 strains) soils were nitrogenase positive as more than 4 n mole $C_2H_4$ per tube per hour by acetylene reduction assay. 2. The acid-producing rhizobia on litmus milk test was observed to be 20% of the total 160 strains isolated from soybean cultivated soil but about 34% of 166 strains isolated from un-cultivated soil. And the serum zone positive strains were higher in the soybean un-cultivated soil than cultivated soil. 3. The population ratio of fast-to slow-growing indigenous rhizobia based on growth pattern of AMA medium was 35.6% to 64.4% of the total 346 strains. 4. The population of indigenous Rhizobium japonicum counted by MPN method was ranged from $9.2{\times}10^2$ cells per gram of soil in soybean un-cultivated soil to $2.3{\times}10^4$ cells per gram of soil soybean cultivated soil. The number of indigenous R. japonicum in 0-10cm depth of surface layer was higher than low layer.

• Journal of The Korean Society of Grassland and Forage Science
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• v.7 no.1
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• pp.25-30
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• 1987

There are differences in opinion as to whether nitrogen fertilizer should be used when establishing alfalfa (Medicago sativa L.). Various reports show that under a hot environment, rhizobia (Rhizobium meliloti) are not as effective in fixing atmospheric nitrogen as they are under moderate temperatures. It is also believed that the addition of nitrogen fertilizer inhibits nodulation of alfalfa seedlings. A replicated experiment was conducted under controlled environmental conditions at the University of Nevada-Reno, Reno, Nevada, USA, to determine the effects of nitrogen application on seedling growth and nodulation of alfalfa grown in a hot environment. Sterile sand was used as the growing media to which a complete nutrient solution minus nitrogen was applied volumetrically to each pot daily. In addition, half of the pots received NH4-$NO_3$, at the rate of 11.2 kg per ha at seeding and at two and four weeks after planting giving a total nitrogen application rate of 33.6 kg per ha during the seven-week experimental period. Rhizobia inoculant (R-12) consisted of a mixture of strains 171-15a, 1682c and 80 PI 265 of (Rhizobium meliloti). Inoculant was applied to the seeds prior to planting and to the sand media at two and four weeks after seeding. Twenty seeds were planted in pots 14.0 cm in diameter and 11.5 cm deep. Plants were thinned to ten plants per pot after emergence and were grown in a controlled environment chamber with a 16-hour light period. Soil temperature at 6 cm depth ranged from 17.4^{\circ}C.$ to 31.1^{\circ}C.$ and had a daily mean of 26.5^{\circ}C.$. Plants were harvested at weekly intervals for seven weeks. Root, shoot and total length, dry weight, volume and number of nodules per plant were determined. Root, shoot, and total length were greater in seedlings grown in soil where nigrogen was applied than that grown in soil to which no nitrogen was applied. The average size of the seedlings as determined by volume and weight was more than two times greater where plants were fertilized with nitrogen. Nodule number per seedling was also greater when nitrogen was applied compared to those which received no nitrogen. The differences were greater as the plants became older. The rhizobia did not fix enough nitrogen for adequate growth of seedlings. This is probably due to high temperature growing conditions that caused the rhizobia to become relatively ineffective as compared to cooler growing conditions. Data suggests it would be desirable to apply nitrogen at seeding when alfalfa is established under hot conditions that occur in mid- or late summer.

• Proceedings of the Korean Society of Crop Science Conference
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• 1988.07a
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• pp.46-47
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• 1988

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.134-135
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• 2002

Legumes are important agricultural and commercial crops characterized by root nodules formed as a result of the symbiotic relationship with nitrogen-fixing rhizobia. Due to the economic significance the chemistry of some of these species has been well recognized. Soybeans and processed soy products, which contain isoflavonoids and saponins, are of wide interest for their multifacted biological effects. (omitted)

• Proceedings of the Korean Society of Life Science Conference
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• 2003.10a
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• pp.126-126
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• 2003

• Korean Journal of Environmental Agriculture
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• v.27 no.4
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• pp.362-367
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• 2008

The legume-rhizobia symbiosis is an important source of plant growth and nitrogen fixation for many agricultural systems. This study was conducted to investigate the effects of salinity stress on nitrogen fixation and growth of pea (Pisum sativum L.), which has antimutagenic activities against chemical mutagen, inoculated with R. leguminosarum bv. viciae cultured with additional plant-to-rhizobia signal compounds, naringenin (NA,15 uM), methyl-jasmonate (MJ, 50 uM) or both, under greenhouse conditions. Three salinity levels (0.6, 3.0 and $6.0\;dS\;m^{-1}$) were imposed at 3 days after transplanting and maintained through daily irrigations. Addition of signal compounds under non-stress and stress conditions increased dry weight, nodule numbers, leaf area and leaf greenness. The inducers increased photosynthetic rate under non-stress and stress conditions, by approximately 5-20% when compared to that of the non-induced control treatment. Under stress conditions, proline content was less in plants treated with plant-to-bacteria signals than the control, but phenol content was significantly increased, compared to that of the control. The study suggested that pre-incubation of bacterial cells with plant-to-bacteria signals could enhance pea growth, photosynthesis, nitrogen fixation and biomass under salinity stress conditions.

• Korean Journal of Soil Science and Fertilizer
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• v.27 no.2
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• pp.136-146
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• 1994

To research the effect of chemotaxis of Rhizobia toward the root exudate on nitrogen fixing ability in soybean Rhizobia symbiosis system. Root exudate from seedlings of Glycine max. L was collected aseptic conditions. B. japonicum KCTC 2422 induced the formation of symbiotic nitrogen fixing nodules on the root of soybean plant and possessed motility and chemotaxis toward the 2mM proline. LPN-100 mutant was $Nod^-$, $Che^+$, and LPN-101 was $Che^-$, $Nod^+$ strains. Physiological properties of mutants were similar to parent strain. The crude root exudate was tested for its chemotactic ability using the capillary tube method. Chemotactic responses of RCR 3407 toward crude root exudate were 2.2, 2.6, 2.9, those of KCTC 2422 were 2.3, 2.9, 3.0, respectively. The crude root exudate was fractionated into neutral, cationic and anionic fractions. Chemotactic responses of KCTC 2422 was least with anionic fraction, most with neutral and intermediate with cationic fraction. B. japonicum KCTC 2422 was attracted by carbohydrates, amino acids and carboxylic acid. Carbohydrates and amino acids were good chemoattractants and carboxylic acids were intermediate chemoattractants. The peak concentration was $10^{-3}M$ for ribose, glucose, glutamine, aspartic acid and carboxylic acids, with exception of xylose, arabinose, tryptophan, which elicited maximum responses at $10^{-4}M$. The formation of nodules and nitrogenase activity of soybean inoculated with KCTC 2422 was determined in 7days after inoculation, and those of LPN-101 was detected in 15days after inoculation, but LPN-100 didn't form of nodules in soybean plants.