• Journal of Plant Biotechnology
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• v.42 no.3
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• pp.186-195
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• 2015

Anthranilate synthase (AS) is a key enzyme in the biosynthesis of tryptophan (Trp), which is the precursor of bioactive metabolites like indole-3-acetic acid and other indole alkaloids. Alpha anthranilate synthase 2 (OsASA2) plays a critical role in the feedback inhibition of tryptophan biosynthesis. In this study, two vectors with single (F124V) and double (S126F/L530D) point mutations of the OsASA2 gene for feedback-insensitive ${\alpha}$ subunit of rice anthranilate synthase were constructed and transformed into wildtype Dongjinbyeo by Agrobacterium-mediated transformation. Transgenic single and double mutant lines were selected as a single copy using TaqMan PCR utilized nos gene probe. To select intergenic lines, the flanking sequence of RB or LB was digested with a BfaI enzyme. Four intergenic lines were selected using a flanking sequence tagged (FST) analysis. Expression in rice (Oryza sativa L.) of the transgenes resulted in the accumulation of tryptophan (Trp), indole-3-acetonitrile (IAN), and indole-3-acetic acid (IAA) in leaves and tryptophan content as a free amino acid in seeds also increased up to 30 times relative to the wildtype. Two homozygous event lines, S-TG1 and D-TG1, were selected for characterization of agronomic traits and metabolite profiling of seeds. Differentially expressed genes (DEGs), related to ion transfer and nutrient supply, were upregulated and DEGs related to co-enzymes that work as functional genes were down regulated. These results suggest that two homozygous event lines may prove effective for the breeding of crops with an increased level of free tryptophan content.

• KSBB Journal
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• v.31 no.3
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• pp.158-164
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• 2016

Plant growth promoting (PGP) hormones, which are produced in a small quantity by bacteria, affect in plant growth and development. PGPs play an important role on the crop productivity in agricultural field. In this study, a photosynthetic bacterial strain producing the PGP was isolated from paddy soil. Bacterial isolate was gram negative, rod-shaped and motility positive. From the 16s rRNA gene sequence analysis, the isolate was identified as Rhodobacter capsulatus PS-2. The mass cultivation of R. capsulatus PS-2 was optimized by considering of the carbon, nitrogen and inorganic salt sources. Optimal medium composition was determined as Na-succinate 4.5 g, yeast extract 5 g, $K_2HPO_4$ 1 g, $MgSO_4$ 5 g, per liter. From the result of 500 L fermentation for 2 days using the optimal medium, the viable cells were $8.7{\times}10^9cfu/mL$. R. capsulatus PS-2 strain produced the carotenoid and indole-3-acetic acid (IAA). The carotenoid extraction and quantitative analysis were performed by HCl-assisting method. Total carotenoid contents from R. capsulatus PS-2 culture broth were measured as $7.02{\pm}0.04$ and $6.93{\pm}0.05mg/L$ under photoheterotrophic and chemoheterotrophic conditions, respectively. To measure the productivity of IAA, colorimetric method was employed using Salkowski reagent at optical density 535 nm. The results showed that the highest content of IAA was $197.44{\pm}5.92mg/L$ in the optimal medium supplemented with 0.3% tryptophan.

• Korean Journal of Environmental Biology
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• v.21 no.3
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• pp.234-239
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• 2003

3-weeks old Commelina was transferred to and grown in Hoagland solution (($\pm 100 \mu M \;Cd^{2+}, 100 \mu M \;Cd^{2+}+10 \mu M\;IAA,100 \mu M\; Cd^{2+}+100 \mu M \; IAA,100 \mu M \; Cd^{2+} +1 \mu M \; IAA)$) for three weeks and then a number of physiological activities was investigated. In the control the length of stem was increased to 7 cm after 3 weeks, but in the treatment of $Cd^{2+}$, 2.0 cm was grown. In cases of IAA with $Cd^{2+}$, the growth of the plants was increased to 3.7 cm, 5.0 cm and 3.3 cm in 100 $\mu$M, 10 $\mu$M and 1 mM IAA respectively, Cadmium stimulated stomatal opening. The stomata, treated with $Cd^{2+}$ opened to n degree of about 6.1 $\mu\textrm{m}$, but the stomata, treated with no cadmium opened to 4.5 $\mu\textrm{m}$. In the treatment of various concentation of IAA with cadmium the stomata opend to about 1 $\mu\textrm{m}$ more than that of cadmium alone. Cadmium reduced total chlorophyll content up to 13% for 3 weeks. In the treatment of $Cd^{2+}$ ＋ IAA (10 $\mu$M and 100 $\mu$M) the clear change of total chlorophyll content was not observed, but in the addition of 1 mM IAA to $Cd^{2+}$ reduced the total chlorophyll content to about 9%. $Cd^{2+}$ reduced to 9% and 11% of Fv/Fm after two and three weeks respectively. In cases of IAA with $Cd^{2+}$, there were no clear changes of Fv/Fm. Cadmium reduced water potential to 67% after 3 weeks incubation, but in cases of IAA with $Cd^{2+}$, water potential was not clearly changed. Therefore, it could be concluded that the treatment of IAA showed clear alleviation of $Cd^{2+}$-induced several physiological toxicities.

• Journal of Plant Biotechnology
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• v.6 no.2
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• pp.113-118
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• 2004

Somatic embryos were formed from calli obtained from axillary shoots (raised from nodal segments of glasshouse-grown plants under aseptic conditions), internodal segments (from in vitro-raised plants), and root and coty-ledonary leaf segments (from in vitro-raised seedlings) after 8 weeks of initial culture. Embryo formation was the highest (97.33%) from cotyledonary leaf callus on Mura-shige and Skoog's (MS) medium containing kinetin (KN) (3 mg/L). Somatic embryo induction was lesser with different combinations of auxins while it increased to 100% in internodal segment and cotyledonary leaf calli with 6-benzyladenine (BA) (2mg/L) along with 2,3,5-triiodobenzoic acid (TIBA) (2mg/L). The shoots were induced from somatic embryos raised from root, coty-ledonary leaf and internodal segment calli grown on MS medium containing BA in combination with indole-3-acetic acid (IAA). Maximum of 66.67% cultures formed shoots on MS medium containing BA (1mg/L) in combination with IAA (2mg/L). The shoots raised from somatic embryos were rooted on MS medium supplemented with indole-3-butyric acid (IBA) (2mg/L). The plantlets transferred to the field showed 70% survival rate after one year.

• Horticultural Science & Technology
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• v.19 no.4
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• pp.459-464
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• 2001

Leaf disks from cultivar 'Kennebec' and one selection line (ND 860-2) were cultured on Murashige-Skoog medium with various combinations of indole acetic acid (IAA) and zeatin riboside. Shoots, roots and callus were induced at various combinations of plant growth regulator levels. The medium containing $3.5mg{\cdot}L^{-1}$ IAA and $4.0mg{\cdot}L^{-1}$ zeatin riboside produced the most plantlets. Rooted regenerants were grown in the greenhouse. The growth of regenerated plants obtained from the MS medium supplemented with $7.0mg{\cdot}L^{-1}$ IAA and $3.0mg{\cdot}L^{-1}$ zeatin riboside was significantly greater than those grown from nodal expalnts. In ND 860-2, a leaf chimera with chlorophyll deficient (light yellow) sectors was found in plants regenerated fiom leaf disks (grown on MS medium supplemented with $3.5mg{\cdot}L^{-1}$ IAA and $3.0mg{\cdot}L^{-1}$ zeatin riboside) but not in plants grown from nodal explants. The phenotypic variability was also observed in the tuber number, size and weight.

• Journal of Microbiology and Biotechnology
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• v.16 no.10
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• pp.1622-1628
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• 2006

Bacteria from the Methylobacterium genus, called pink-pigmented facultative methylotrophic bacteria (PPFMs), are common inhabitants of plants, potentially dominating the phyllosphere population, and are also encountered in the rhizosphere, seeds, and other parts of plants, being versatile in nature. The consistent success of the Methylobacterium plant association relies on methylotrophy, the ability to utilize the one-carbon compound methanol emitted by plants. However, the efficiency of Methylobacterium in plant growth promotion could be better exploited and thus has attracted increasing interest in recent years. Accordingly, the present study investigated the inoculation effects of Methylobacterium sp. strains CBMB20 and CBMB 110 on seed imbibition to tomato and red pepper on the growth and accumulation of phytohormone levels under gnotobiotic conditions. Seeds treated with the Methylobacterium strains showed a significant increase in root length when compared with either the uninoculated control or Methylobacterium extorquens $miaA^-$ knockout mutanttreated seeds. Extracts of the plant samples were used for indole-3-acetic acid (IAA), trans-zeatin riboside (t-ZR), and dihydrozeatin riboside (DHZR) assays by immunoanalysis. The treatment with Methylobacterium sp. CBMB20 or CBMB 110 produced significant increases in the accumulation of IAA and the cytokinins t-ZR and DHZR in the red pepper extracts, whereas no IAA was detected in the tomato extracts, although the cytokinin concentrations were significantly increased. Therefore, this study proved that the versatility of Methylobacterium as a plant-growth promoting bacteria could be better exploited.

• Journal of Microbiology and Biotechnology
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• v.30 no.5
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• pp.717-725
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• 2020

The use of plant growth-promoting rhizobacteria is economically viable and environmentally safe for mitigating various plant stresses. Abiotic stresses such as flood and drought are a serious threat to modern agriculture. In the present study, the indole-3-acetic acid-producing rhizobacterium R. sphaeroides KE149 was selected, and its effects on the growth of adzuki bean plants under flood stress (FS) and drought stress (DS) were investigated. IAA quantification of bacterial pure culture revealed that KE149 produced a significant amount of IAA. Moreover, KE149 inoculation notably decreased stress-responsive endogenous abscisic acid and jasmonic acid and increased salicylic acid in plants under DS and FS. KE149 inoculation also increased proline under DS and methionine under FS. In addition, KE149 inoculation significantly increased the levels of calcium (Ca), magnesium (Mg), and potassium (K) while lowering the sodium (Na) content in the plant shoot under stress. KE149-treated plants had markedly greater root length, shoot length, stem diameter, biomass, and higher chlorophyll content under both normal and stressed conditions. These results suggest that KE149 could be an efficient biofertilizer for mitigating water stress.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.4
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• pp.235-244
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• 2004

In this study, we compared the levels of methylotrophic bacterial community diversity in the leaf samples of 19 rice cultivars collected from three regions of Korea. Nineteen pink pigmented isolates showing characteristic growth on methanol were obtained. Physiological and biochemical characters of each isolate were examined according to methods described in Bergey's Manual of Systematic Bacteriology. When phylotypes were defined by performing numerical analysis of 37 characteristics, four distinct clusters were formed. The two reference strains, Methylobacterium extorquens AM1 and Methylobacterium fujisawaense KACC10744 were found to group under cluster IV and cluster III respectively. Cluster I diverged on the basis of nitrate reduction and four isolates showed tolerance upto 0.5 M NaCl concentrations. Two strains in cluster I and III were found to possess methane utilizing properties. Most of the isolates in all the four clusters utilized monosaccharides, disaccharide and polyols as carbon source. When the isolates were subjected for indole-3-acetic acid (IAA) analysis in the presence of L-tryptophan, only 8 isolates exhibited IAA production. In addition, the nitrogen source in the medium was found to influence the IAA production. Addition of $(NH_4)_2SO_4$ in the medium led to a 2 to 30 fold increase in the indole synthesis. However, $KNO_3$, $NH_4NO_3$ and $NH_4Cl$ substitution did not significantly stimulate the synthesis of IAA in the growth medium. Result of gnotobiotic root elongation assay significantly increased roots and shoots lengths, and number of lateral roots, which is mediated by IAA production in the culture medium. The rice seedlings primary roots from seeds treated with methylotrophic isolates were on average 27 to 56% longer than the roots from seeds treated with the uninoculated seeds. In addition, application of different high concentrations of authentic IAA ($400g\;mL^{-1}$) to roots of rice seedlings inhibited root growth. However, the IAA concentration from 10 to $200g\;mL^{-1}$, IAA promoted root growth of rice seedlings. These results suggest that bacterial IAA plays a major role in the development of the host plant root system.

• Horticultural Science & Technology
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• v.33 no.3
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• pp.317-325
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• 2015

Peach (Prunus persica L.) is a model species for stone fruit studies within the Rosaceae family. Auxin plays an important role in the development of peach fruit. To reveal the distribution of auxin in the tissues of peach fruit, immunohistochemical localization of IAA was carried out in the seed, mesocarp, and endocarp in developing peach fruit using an anti-indole-3-acetic acid (anti-IAA) monoclonal antibody. A strong IAA signal was observed throughout the outer and inner integument during peach fruit development, and the distribution was zonal. The IAA signal was mainly focused in mucilage layers in the outer integument. The outer integument may function to produce or store IAA in the seed; a strong IAA signal was detected in the cells around the vascular tissue, whereas a weak IAA signal was located in the vascular tissues. In the mesocarp, the cells around the vascular bundle tissue gave rise to an IAA signal that increased in the late phase of fruit growth, which coincided with a significant increase in fruit growth. The distribution of IAA, however, was changed when fruit was treated with auxin transport inhibitors NPA (1-N-naphthylphthalamic acid) or TIBA (2, 3, 5-triiodobenzoic acid); in mesocarp tissues, an IAA signal was detected mainly in vessels of the treated fruit. During the critical period of endocarp lignification, the vessel lignification process was negatively correlated with IAA signal. The present results confirmed that the distribution of IAA was different in various tissues of peach fruit according to the developmental stage. This research provides cytological data for further study of the regulatory mechanism of auxin in peach fruit.

• Korean Journal of Microbiology
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• v.19 no.2
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• pp.52-62
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• 1981

In order to interpret the effect of IAA on the phosphate metabolism and biosynthesis of organic compounds, Saccharomyces uvarum were cultured in the media treated with various concnetration of IAA $(10^{-3}M,\;10^{-5}M,\;10^{-7}M)$. Sampling at the beginning and intervals of culture, yeast cells fractionated were traced the contents of inorganic phosphate and organic compounds of various fractions. 1. Growth of Saccharomyces uvarum were enhanced by IAA $(10^{-3}M,\;10^{-5}M)$ and phosphate contents in DNA and RNA fractions treated with IAA were accelerated 2.3 times and 2 times in comparison with those of control. 2. Amounts of poly-P"A" and poly-p"B" were increased but poly-P"C" decreased during the culture. Therefore, it is considered that poly-P"C" play on most important role as a phosphate pool. 3. It is suggested that because phosphate contents in DNA, protein and lipid fractions increased, inorganic phosphates required phosphates required RNA were transferred from phosphates in cytoplasm, because these increased slowly during the culture. 4. Alkali-labile protein were accelerated by IAA and alkali stable protein only were inhibiction were enhanced by IAA while, ethanol : ether soluble fraction was induced by $10^{-7}M$ IAA in comparison with those control.X> IAA in comparison with those control.