• Molecules and Cells
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• v.19 no.2
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• pp.228-231
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• 2005

Recent characterization of several genes involved in plant defense responses suggested that ubiquitin-mediated protein degradation has a role in these responses. We isolated two cDNAs (NtUBA1 and NtUBA2) encoding ubiquitin-activating enzyme (E1) from Nicotiana tabacum cv. BY-2. The open reading frames of both encoded 1080 amino acids, corresponding to molecular masses of 120 kDa. The E1s and corresponding transcripts were upregulated by infection with tobacco mosaic virus (TMV) and tomato mosaic virus (ToMV), and to a lesser extent by cucumber mosaic virus (CMV). Furthermore, they were also upregulated by wounding stress, and the plant hormones salicylic acid, jasmonic acid and the ethylene precursor, aminocyclopropane-1-carboxylic acid (ACC). Our findings support the idea that the ubiquitin-proteasome system plays a role in plant disease defenses.

• Korean Journal of Microbiology
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• v.53 no.4
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• pp.251-256
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• 2017

Some rhizobacteria were isolated, that have copper resistance and can confer copper resistance to plants allowing growth under copper stress. Isolated strains Pseudomonas veronii MS1 and P. migulae MS2 produced 0.13 and 0.26 mmol/ml of siderophore, that is a metal-chelating agent, and also showed 64.6 and 77.9% of biosorption ability for Cu in 20 mg/L Cu solution, respectively. Copper can catalyze a formation of harmful free radicals, which may cause oxidative stress in organisms. Removal activity of 1,1-diphenyl-2-picryl hydrazyl radical and antioxidant capacity of strains MS1 and MS2 increased up to 82.6 and 78.1%, respectively compared to those of control at 24 h of incubation. They exhibited 7.10 and $6.42{\mu}mol$ ${\alpha}$-ketobutyrate mg/h of 1-aminocyclopropane-1-carboxylic acid deaminase activity, respectively, which reduced levels of stress hormone, ethylene in plants, and also produced indole-3-acetic acid and salicyclic acid that can help plant growth under abiotic stress. All these results indicated that these copper-resistant rhizobacteria could confer copper resistance and growth promotion to plants.

• Journal of Life Science
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• v.25 no.1
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• pp.37-43
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• 2015

We have investigated the effects of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC), indole-3-acetic acid (IAA) and methyl jasmonate (MeJA) on the development of aerenchyma in the primary root of maize (Zea mays). Because plant hormones affected the longitudinal organization of the primary root, we need an indicator to direct the positions for comparison between control and hormone-treated roots. Therefore, the zones of the maize primary root were categorized as PR25, PR50 and PR75, where each value indicates the relative position between the root tip (PR0) and the base (PR100). Aerenchyma was not observed at PR25 and PR50 and rarely found at PR75 in the cortex of control roots. The aerenchymal area at PR75 increased in the presence of the ethylene precursor ACC or a natural auxin IAA. On the other hand, MeJA differentially acted on non-submerged and submerged roots. Exogenously applied MeJA suppressed the aerenchyma formation in non-submerged roots. When the primary root was submerged, aerenchymal area expanded prominently. The submergence-induced aerenchyma formation was amplified with MeJA. Lateral root primordia have been known to inhibit aerenchymal death of surrounding cells. All the three hormones stimulating aerenchyma formation as described above did not restore the inhibition caused by lateral root primordia, suggesting that the inhibitory step regulated by lateral root primordia can be located after hormonal signaling steps.

• Journal of Plant Biology
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• v.39 no.4
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• pp.295-300
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• 1996

The physiological effects of oligogalacturonic acid (OGA:D. P. 6-7), a product of acid hydrolysis of polygalacturonic acid (PGA), on ethylene biosynthesis in mung bean (Vigna radiata W.) hypocotyl segments was studied. Among PGA, OGA and monogalacturomic acid (MGA), only OGA stimulated ethylene production in mung bean hypocotyl segments, and the most effective concentraton of OGA was 50$\mu\textrm{g}$/mL. Time course data indicated that this stimulatiion effect of OGA appeared after 90 min incubation period and continued until 24 h. When indol-3-acetic acid (IAA) and 1-aminocyclopropane-1-carboxylic acid (ACC) were treated with OGA to investigate the mechanism of OGA on ethylene production, they did not show synergistic effects on ethylene production. The stimulation of ethylene production by OGA was due to the increase of in vivo ACC synthase activity, but OGA treatment had no effect of in vivo ACC oxidase activity. The effect of aminoethoxy vinyl glycine (AVG) and Co2+, the inhibitor of ethylene synthesis, was siminished a little by the OGA, but the treatment of Ca2+, known to increase ACC, with OGA did not increase the ethylene production, this effect seems to be specific for Ca2+ because other divalent cation, Mg2+, did not show the inhibition of OGA-indyuced ethylene production. It is possible that the OGA adopts a different signal transduction pathway to the ethylene bioxynthesis.

• Microbiology and Biotechnology Letters
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• v.47 no.1
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• pp.1-10
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• 2019

Saline soils comprise more than half a billion hectares worldwide. Thus, they warrant attention for their efficient, economical, and environmentally acceptable management. Halophytes are being progressively utilized for human benefits. The halophyte microbiome contributes significantly to plant performance and can provide information regarding complex ecological processes involved in the osmoregulation of halophytes. Microbial communities associated with the rhizosphere, phyllosphere, and endosphere of halophytes play an important role in plant health and productivity. Members of the plant microbiome belonging to domains Archaea, Bacteria, and kingdom Fungi are involved in the osmoregulation of halophytes. Halophilic microorganisms principally use compatible solutes, such as glycine, betaine, proline, trehalose, ectoine, and glutamic acid, to survive under salinity stress conditions. Plant growth-promoting rhizobacteria (PGPR) enhance plant growth and help to elucidate tolerance to salinity. Detailed studies of the metabolic pathways of plants have shown that plant growth-promoting rhizobacteria contribute to plant tolerance by affecting the signaling network of plants. Phytohormones (indole-3-acetic acid and cytokinin), 1-aminocyclopropane-1-carboxylic acid deaminase biosynthesis, exopolysaccharides, halocins, and volatile organic compounds function as signaling molecules for plants to elicit salinity stress. This review focuses on the functions of plant microbiome and on understanding how the microorganisms affect halophyte health and growth.

• Korean Journal of Microbiology
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• v.53 no.4
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• pp.257-264
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• 2017

Pseudomonas veronii MS1 and P. migulae MS2 have several mechanisms of copper resistance and plant growth promoting capability, and also can alleviate abiotic stress in plant by hydrolysis of a precursor of stress ethylene, 1-aminocyclopropane-1-carboxylic acid (ACC) by ACC deaminase. In 4-week pot test for tomato growth in soil contained 700 mg/kg Cu, inoculation of MS1 and MS2 significantly increased root and shoot lengths, wet weight and dry weight of tomato plants compared to those of uninoculated control. The inoculated tomato plants contained less amounts of proline that can protect plants from abiotic stress, and malondialdehyde, an oxidative stress marker than those of control. ACC synthase genes, ACS4 and ACS6, and ACC oxidase genes, ACO1 and ACO4, both involved in ethylene synthesis, were strongly expressed in Cu stressed tomato, whereas significantly reduced in tomato inoculated with MS1 and MS2. Also, a gene encoding a metal binding protein metallothionein, MT2 showed similar expression pattern with above genes. All these results indicated that these rhizobacteria could confer Cu resistance to tomato plant under Cu stress and allowed a lower level of Cu stress and growth promotion.

• Molecules and Cells
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• v.38 no.7
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• pp.597-603
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• 2015

Biosynthesis of the phytohormone ethylene is under tight regulation to satisfy the need for appropriate levels of ethylene in plants in response to exogenous and endogenous stimuli. The enzyme 1-aminocyclopropane-1-carboxylic acid synthase (ACS), which catalyzes the rate-limiting step of ethylene biosynthesis, plays a central role to regulate ethylene production through changes in ACS gene expression levels and the activity of the enzyme. Together with molecular genetic studies suggesting the roles of post-translational modification of the ACS, newly emerging evidence strongly suggests that the regulation of ACS protein stability is an alternative mechanism that controls ethylene production, in addition to the transcriptional regulation of ACS genes. In this review, recent new insight into the regulation of ACS protein turnover is highlighted, with a special focus on the roles of phosphorylation, ubiquitination, and novel components that regulate the turnover of ACS proteins. The prospect of cross-talk between ethylene biosynthesis and other signaling pathways to control turnover of the ACS protein is also considered.

• Microbiology and Biotechnology Letters
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• v.40 no.3
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• pp.261-267
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• 2012

Coastal sand dunes are important for ecosystems due to the variety of rare species that can be found in this kind of habitat, and the beautiful landscapes they create. For environmental remediation, a potential strategy is phytoremediation using the symbiotic relationship of plants and microbes in the rhizosphere, which has proven ecologically sound, safe, and cost effective. Ninety-five colonies were isolated from the rhizosphere soil (RS) or rhizoplane (RP) of Rorippa islandica, Rumex crispus, Artemisia princeps var. orientalis, Lilium sp Stellaria media, and Gramineae. These colonies were then tested for plant growth promoting activities (PGPAs) such as 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, and siderphores synthesis ability. In addition, salt tolerance was evaluated at 4% and 8% salt concentrations. It was observed that amongst the test subjects about 50% of the strains had a high resistance to salinity. Many of them could produce indole-3-acetic acid (IAA) IAA (in RS 13.9% and in RP 7.6%), exhibited ACC deaminase activity (55.8% in RS and 36.6% in RP), and could synthesize siderphores (62.7% in RS and 50% in RP). Correlation coefficient analyses were carried out for the three kinds of plant growth promoting abilities (PGPA) and salt tolerance. A positive correlation was found between an ability to synthesize siderphores and ACC deaminase activity (r=0.605, p<0.037). Similarly, positive correlations were noted between salt tolerance and ACC deaminase activity (r=0.762, p<0.004, r=0.771), and salt tolerance and an ability to synthesize siderphores (r=0.771, p<0.003).

• Microbiology and Biotechnology Letters
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• v.38 no.3
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• pp.302-307
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• 2010

Nitrogen is an element need to grow plants growth. Plants take up nitrogen in the form of nitrate or ammonium. Most of plants absorb nitrogen source as fertilizers. But from 50 to 70% of fertilizers applied were washed away. This study was conducted to isolate free-living nitrogen fixing bacteria from reed and to examine its beneficial traits for developing sustainable biofertilizers. Enriched consortium obtained from a reed in Ansan was developed for the fixing of nitrogen. Nitrogen fixing bacteria isolated from an enriched culture in Congo Red Medium was analyzed by 16s rDNA sequencing. AKC-10 was isolated and shown to have excellent nitrogen fixing ability. The optimum conditions of nitrogen fixing ability were $25^{\circ}C$ ($237.50{\pm}39.65\;nmole{\cdot}mg-protein^{-1}{\cdot}h^{-1}$ and pH 7 ($168.335{\pm}12.84$ nmole/hr mg-protein). It was identified as Microbacterium hominis [(AKC-10 (similarity : 99%)]. This strain was had to IAA (indole-3-acetic acid) productivity and ACC(1-aminocyclopropane-1-carboxylic acid) deaminase activity. Therefore, Microbacterium hominis AKC-10 stimulated plant development in the soil, enhancing the efficiency of remediation.

• Journal of Mushroom
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• v.19 no.3
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• pp.134-139
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• 2021

A diverse group of plant-growth promoting bacteria were isolated in button mushroom (Agaricus bisporus) media to investigate the plant-growth promoting traits of compounds including indole acetic acid (IAA), ammonia, 1-aminocyclopropane-1-carboxylic acid deaminase, siderophore, and hydrogen cyanide. Twenty-one bacterial strains showing positive effects for all the test traits were selected and classified to confirm bacterial diversity in the media habitat. Plant-growth promoting traits of the isolates were also assessed. All strains produced IAA ranging from 20 ㎍/mL to 250 ㎍/mL. Most of the isolates produced more than 80% siderophore. Four strains (Pantoea sp., PSB-08, Bacillus sp., PSB-13, Pseudomonas sp., PSB-17, and Enterobacter sp., PSB-21) showed outstanding performances for all the tested traits. In a bioassay of these four strains using mung bean plant, the best growth performances (23.16 cm, 22.98 cm, 2.27 g/plant, and 1.83 g/plant for shoot length, root length, shoot dry weight, and root dry weight, respectively) were obtained from the plants co-inoculated with Bacillus sp., PSB-13. The resultant data indicate that button mushroom media have got a diverse group of bacteria with plant growth promoting abilities. Thus, the media could be a good recycling resource for using to an effective bio-fertilizer.