• Journal of Microbiology and Biotechnology
• /
• v.34 no.3
• /
• pp.570-579
• /
• 2024

Root-nodule nitrogen-fixing bacteria are known for being specific to particular legumes. This study isolated the endophytic root-nodule bacteria from the nodules of legumes and examined them to determine whether they could be used to promote the formation of nodules in other legumes. Forty-six isolates were collected from five leguminous plants and screened for housekeeping (16S rRNA), nitrogen fixation (nifH), and nodulation (nodC) genes. Based on the 16S rRNA gene sequencing and phylogenetic analysis, the bacterial isolates WC15, WC16, WC24, and GM5 were identified as Rhizobium, Sphingomonas, Methylobacterium, and Bradyrhizobium, respectively. The four isolates were found to have the nifH gene, and the study confirmed that one isolate (GM5) had both the nifH and nodC genes. The Salkowski method was used to measure the isolated bacteria for their capacity to produce phytohormone indole acetic acid (IAA). Additional experiments were performed to examine the effect of the isolated bacteria on root morphology and nodulation. Among the four tested isolates, both WC24 and GM5 induced nodulation in Glycine max. The gene expression studies revealed that GM5 had a higher expression of the nifH gene. The existence and expression of the nitrogen-fixing genes implied that the tested strain had the ability to fix the atmospheric nitrogen. These findings demonstrated that a nitrogen-fixing bacterium, Methylobacterium (WC24), isolated from a Trifolium repens, induced the formation of root nodules in non-host leguminous plants (Glycine max). This suggested the potential application of these rhizobia as biofertilizer. Further studies are required to verify the N₂-fixing efficiency of the isolates.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.24 no.2
• /
• pp.75-81
• /
• 1979

15 soybean cultivars were tested with the sandculture to investigate the affinity of cultivars to the nodule bacteria, Rhyzobium Japonicum #23, and the effects of inoculation on the vegetative growth of cultivars. The amount of nodule formation until the flowering stage was significantly different among the cultivars. The cultivar Haman showed the best nodule formation of 122.2 nodules per plant, while the cultivar Busuk showed the least amount of nodule formation. The inoculation of the nodule bacteria resulted in an increased plant growth and especially the chlorophyll content was significantly improved by inoculation of the nodule bacteria.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.49 no.4
• /
• pp.316-324
• /
• 2004

Sinorhizobium sp. strain MUS10 forms nitrogen-fixing stem nodules on Sesbania rostrata, a tropical green manure crop. In this study, the ultrastructural events associated with the formation of stem nodules were investigated. Sinorhizobium sp. strain MUS10 entered the host tissue through cracks created by the emerging adventitious root primordia and multiplied within the intercellular spaces. During early phases of infection, host cells adjacent to invading bacteria revealed cellular damage that is typical of hypersensitive reactions, while the cells at the inner cortex exhibited meristematic activity. Infection threads were numerous in S-day-old nodules and often were associated with the host cell wall. In several cases, more than one infection thread was found in individual cells. The junction at which the host cell walls converged was often enlarged due to fusion of intracellular branches of infection threads resulting in large infection pockets. The infection threads were made up of a homogeneous, amorphous matrix that enclosed the bacteria. Several finger-like projections were seen radiating from these enlarged infection threads and were delineated from the host cytoplasm by the plasma membrane. As in Azorhizobium caulinodans induced root nodules, the release of Sinorhizobia from the infection threads into the plant cells appears to be mediated by 'infection droplets'. A 15-day­old Sesbania stem nodule revealed typical ultrastructure features of a determinate nodule, containing several bacterioids within symbiosomes.

• Current Research on Agriculture and Life Sciences
• /
• v.5
• /
• pp.40-51
• /
• 1987

This experiment was conducted to search for Rhizobia with good nitrogen fixation abilities and to investigate their physiological characteristics isolated from 12 soybean cultivars and the affinities of root nodule bacteria with soybeans. The results obtained were as follows; Based on colors, Rhizobia grown on YMA medium were divided into 3 groups, i. e., white, translucent and transparent, amounting to 60, 30 and 10%, respectively. In litmus milk reaction, the strains which produced alkali, acid serum, alkaline serum and acid reached to 51, 29, 9 and 11%, respectively. Strains, S022, and S096 were slow-growers and produced alkaili, while strains, S080, S-090, and S118 were fastgrowers and produced acid. The growth of root nodule bacteria on YMA medium was favorable between the initial pHs of 6.0~7.0. Glutamine, asparagine and al1antoin as nitrogen sources enhanced the growth of root nodule bacteria. All the strains tested formed nodules on the soybean roots, and the strains with good symbiotic nitrogen fixation abilities that had white color, small colony, nitrate reduction abilities and no nitrite reduction abilities showed comparatively high nitrogen fixing activities. Some strains varied in nitrogen fixing activities according to soybean cultivars, and a few strains fanned ineffective nodules which showed no nitrogen fixing activity.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.48 no.5
• /
• pp.361-368
• /
• 2003

The responses of five varieties and three cultivars of pea (Pisum sativum) to Rhizobium inoculation on nodulation, growth, nitrogenase activity, dry matter production and N uptake were investigated. The pea varieties were IPSA Motorshuti-l, IPSA Motorshuti-2, IPSA Motorshuti-3, BARI Motorshuti-l, BARI Motorshuti-2 and the cultivars were 063, Local small and Local white. Fifty percent seeds of each pea variety/cultivar were inoculated with a mixture of Rhizobium inoculants at rate of 15g/kg seed and the remaining fifty percent seeds were kept uninoculated. The plants inoculated with Rhizobium inoculant significantly increased nodulation, growth, nitrogenase activity, dry matter production and N uptake. Among the varieties/cultivars, BARI Motorshuti-l performed best in almost all parameters including nitrogenase activity of root nodule bacteria of the crop. There were positive correlations among the number and dry weight of nodules (r=$0.987^{**}$, $0.909^{**}$), nitrogenase activity of root nodule bacteria (r=$0.944^{**}$, $0.882^{**}$), dry weight of shoot (r=$0.787^{**}$, $0.952^{**}$), N content (r=$0.594^{**}$, $0.605^{**}$) and N uptake (r=$0.784^{**}$, $0.922^{**}$) by shoot both at flowering and pod filling stages of the crop, respectively. It was concluded that BARI Motorshuti-l in symbiotic association with Rhizobium inoculant performed best in recording nitrogenase activity, dry matter production and N uptake by pea.

• Korean Journal of Microbiology
• /
• v.49 no.2
• /
• pp.131-136
• /
• 2013

This study was conducted to select rhizobia from hairy vetch (Vicia villosa Roth) with nodulation and excellent nitrogen-fixing ability. Hairy vetch root was collected from 7 of cultivation region of all over the country, rhizobia were isolated from the root nodules. Isolates were re-inoculated into a hairy vetch separately and studied nodulation and nitrogen-fixing ability. As a result, total of 52 Rhizobium isolates were isolated from the hairy vetch root nodules, among these, 16 isolates were Rhizobium which show good growth at more than 0.5% NaCl concentration. These 16 isolates were re-inoculated separately, 8 weeks after, good root nodule formation was observed from Rhizobium sp. RH1, RH3, RH81, RH82, RH84, and RH93 strain treated samples. Six isolates were positive for nitrogen fixing ability, the highest acetylene reduction activity was shown by Rhizobium sp. RH84. Results suggest that the Rhizobium sp. RH84 could be used as the possibility of its application as a green manure crop of hairy vetches in nonuniform salt distribution reclaimed land.

• Molecules and Cells
• /
• v.24 no.2
• /
• pp.185-193
• /
• 2007

Symbiotic nitrogen fixation with nitrogen-fixing bacteria in the root nodules is a distinctly beneficial metabolic process in legume plants. Legumes control the nodule number and nodulation zone through a systemic negative regulatory system between shoot and root. Mutation in the soybean NTS gene encoding GmNARK, a CLAVATA1-like serine/threonine receptor-like kinase, causes excessive nodule development called hypernodulation. To examine the effect of nts mutation on the gene expression profile in the leaves, suppression subtractive hybridization was performed with the trifoliate leaves of nts mutant 'SS2-2' and the wild-type (WT) parent 'Sinpaldalkong2', and 75 EST clones that were highly expressed in the leaves of the SS2-2 mutant were identified. Interestingly, the expression of jasmonate (JA)-responsive genes such as vspA, vspB, and Lox2 were upregulated, whereas that of a salicylate-responsive gene PR1a was suppressed in the SS2-2 mutant. In addition, the level of JA was about two-fold higher in the leaves of the SS2-2 mutant than in those of the WT under natural growth conditions. Moreover, the JA-responsive gene expression persists in the leaves of SS2-2 mutant without rhizobia infection in the roots. Taken together, our results suggest that the nts mutation increases JA synthesis in mature leaves and consequently leads to constitutive expression of JA-responsive genes which is irrelevant to hypernodulation in the root.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.48 no.5
• /
• pp.355-360
• /
• 2003

The responses of six mungbean [Vigna radiata (L.) Wilczek] varieties to Rhizobium inoculation on number and dry weight of nodules, nitrogenase activity of root nodule bacteria, dry weight of shoot and root, nitrogen content, and uptake by shoot were investigated. The mungbean varieties were BARI Mung-2, BARI Mung-3, BARI Mung-4, BARI Mung-5, BINA Moog-2, and BU Mung-1. Two-third seeds of each variety were inoculated with Rhizobium inoculant and the remaining one-third seeds were kept uninoculated. Rhizobium strains TAL 169 and TAL 441 were used for inoculation of seeds. Inoculation of seeds with Rhizobium strains significantly increased nodulation, nitrogenases activity, dry matter production, nitrogen content, and uptake by shoot of the crop compared to uninoculated control. There was positive correlation among the number and dry weight of nodules, nitrogenase activity, dry weight of shoot and root, nitrogen content, and uptake by shoot of the crop. It was concluded that BARI Mung-4 in association with Rhizobium strain TAL 169 performed best in recording nodulation, nitrogenase activity, dry matter production, and nitrogen uptake by shoot of mungbean.

• Molecules and Cells
• /
• v.27 no.2
• /
• pp.129-134
• /
• 2009

Legume plants develop root nodules to recruit nitrogen-fixing bacteria called rhizobia. This symbiotic relationship allows the host plants to grow even under nitrogen limiting environment. Since nodule development is an energetically expensive process, the number of nodules should be tightly controlled by the host plants. For this purpose, legume plants utilize a long-distance signaling known as autoregulation of nodulation (AON). AON signaling in legumes has been extensively studied over decades but the underlying molecular mechanism had been largely unclear until recently. With the advent of the model legumes, L. japonicus and M. truncatula, we have been seeing a great progress including isolation of the AON-associated receptor kinase. Here, we summarize recent studies on AON and discuss an updated view of the long-distance control of nodulation.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.37 no.2
• /
• pp.114-123
• /
• 2009

To investigate the possible use of plants for landscaping in reclaimed soil, a planting pilot system experiment was performed over the course of four years in reclaimed dredging area with four species: Alnus firma, Alnus hirsuta, Pinus thunbergii, and Pyrachantha angustifolia for 4 years. The physicochemical characteristics of the tested soil showed that it was sandy through coming from a reclaimed dredging area. The average pH of the tested soil was 7.16(slight alkali), and electric conductivity(EC) was relatively low, $294{\mu}S/cm$, even though it came from a saltwater area. To test the effect of planting density vs. phytomass by plant specie from a planting basin, the experiment was designed using four plant species with high and low planting densities over 4 years. The planting conditions of the growth of landscape tree species exhibited growth height as follows: A. hirsuta, A. firma, P. thunbergii, and P. angustifolia, whill the DBH followed the order of A. hirsuta, A. firma, and P. thunbergii. The total phytomass of each plant was higher at low density planting areas than high density planting area in terms of total phytomass production and growth distribution in the reclaimed dredging area. Total phytomass per unit area increased as follows: A. hirsuta, A. firma, P. thunbergii, and P. angustifolia. The total phytomass per each tested plant was 2 times higher in low density planting areas than high density planting areas. Total phytomass per unit area, however, was similar or slighty higher in high density planting areas compared to low density areas. Among the tested plants, A. hirsuta showed the highest phytomass, implying that A. hirsuta adapted very well to the reclaimed area and has the capability of a fast growth, nitrogen fixation tree, and utilizing insoluble nutrients through inoculated root nodule bacteria. The yield of phytomass per individual in low density Alnus species was greater than that of the high density. However, those per unit areas had no difference in the density-dependent planting. The ratio of belowground to aboveground was $0.21{\sim}0.26$. Thus, it could be concluded that the Alnus species are potential candidates for ornamental tree species in reclaimed dredging areas. This study offers baseline data for the use of ornamental tree species in reclaimed dredging areas. Additional research is required for different ornamental species in order to increase phytomass of a planting conditions based on reclaimed dredging areas.