• Journal of Microbiology and Biotechnology
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• v.24 no.8
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• pp.1015-1025
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• 2014

Microorganisms that live in the rhizosphere play a pivotal role in the functioning and maintenance of soil ecosystems. The study of rhizospheric cyanobacteria has been hampered by the difficulty to culture and maintain them in the laboratory. The present work investigated the production of the plant hormone indole-3-acetic acid (IAA) and the potential of biofilm formation on the rhizoplane of pea plants by two cyanobacterial strains, isolated from rice rhizosphere. The unicellular cyanobacteria Chroococcidiopsis sp. MMG-5 and Synechocystis sp. MMG-8 that were isolated from a rice rhizosphere, were investigated. Production of IAA by Chroococcidiopsis sp. MMG-5 and Synechocystis sp. MMG-8 was measured under experimental conditions (pH and light). The bioactivity of the cyanobacterial auxin was demonstrated through the alteration of the rooting pattern of Pisum sativum seedlings. The increase in the concentration of L-tryptophan and the time that this amino acid was present in the medium resulted in a significant enhancement of the synthesis of IAA (r > 0.900 at p = 0.01). There was also a significant correlation between the concentration of IAA in the supernatant of the cyanobacteria cultures and the root length and number of the pea seedlings. Observations made by confocal laser scanning microscopy revealed the presence of cyanobacteria on the surface of the roots and also provided evidence for the penetration of the cyanobacteria in the endorhizosphere. We show that the synthesis of IAA by Chroococcidiopsis sp. MMG-5 and Synechocystis sp. MMG-8 occurs under different environmental conditions and that the auxin is important for the development of the seedling roots and for establishing an intimate symbiosis between cyanobacteria and host plants.

• Journal of Life Science
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• v.32 no.11
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• pp.872-881
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• 2022

In this study, we optimized the composition of the indole-3-acetic acid (IAA) production medium using response surface methodology on Pantoea agglomerans SRCM 119864 isolated from soil. IAA-producing P. aglomerans SRCM 119864 was identified by 16S rRNA gene sequencing. There are 11 intermediate components known to affect IAA production, hence the effect of each component on IAA production was investigated using a Plackett-Burman design (PBD). Based on the PBD, sucrose, tryptone, and sodium chloride were selected as the main factors that enhanced the IAA production at optimal L-tryptophan concentration. The predicted maximum IAA production (64.34 mg/l) was obtained for a concentration of sucrose of 13.38 g/l, of tryptone of 18.34 g/l, of sodium chloride of 9.71 g/l, and of L-tryptophan of 6.25 g/l using a the hybrid design experimental model. In the experiment, the nutrient broth medium supplemented with 0.1% L-tryptophan as the basal medium produced 45.24 mg/l of IAA, whereas the optimized medium produced 65.40 mg/l of IAA, resulting in a 44.56% increase in efficiency. It was confirmed that the IAA production of the designed optimal composition medium was very similar to the predicted IAA production. The statistical significance and suitability of the experimental model were verified through analysis of variance (ANOVA). Therefore, in this study, we determined the optimal growth medium concentration for the maximum production of IAA, which can contribute to sustainable agriculture and increase crop yield.

• Journal of Microbiology and Biotechnology
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• v.34 no.6
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• pp.1239-1248
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• 2024

Peatlands are marginal agricultural lands due to highly acidic soil conditions and poor drainage systems. Drought stress is a big problem in peatlands as it can affect plants through poor root development, so technological innovations are needed to increase the productivity and sustainability of upland rice on peatlands. Rhizobacteria can overcome the effects of drought stress by altering root morphology, regulating stress-responsive genes, and producing exopolysaccharides and indole acetic acid (IAA). This study aimed to determine the ability of rhizobacteria in upland rice to produce exopolysaccharides and IAA, identify potential isolates using molecular markers, and prove the effect of rhizobacteria on viability and vigor index in upland rice. Rhizobacterial isolates were grown on yeast extract mannitol broth (YEMB) medium for exopolysaccharides production testing and Nutrient Broth (NB)+L-tryptophan medium for IAA production testing. The selected isolates identify using sequence 16S rRNA. The variables observed in testing the effect of rhizobacteria were germination ability, vigour index, and growth uniformity. EPS-1 isolate is the best production of exopolysaccharides (41.6 mg/ml) and IAA (60.83 ppm). The isolate EPS-1 was identified as Klebsiella variicola using 16S rRNA sequencing and phylogenetic analysis. The isolate EPS-1 can increase the viability and vigor of upland rice seeds. K. variicola is more adaptive and has several functional properties that can be developed as a potential bioagent or biofertilizer to improve soil nutrition, moisture and enhance plant growth. The use of rhizobacteria can reduce dependence on the use of synthetic materials with sustainable agriculture.

• Journal of Microbiology and Biotechnology
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• v.20 no.3
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• pp.587-593
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• 2010

Three hundred and seventy-four rhizobacteria were isolated from the rhizosphere soil (RS) or rhizoplane (RP) of Echinochloa crus-galli, Carex leiorhyncha, Commelina communis, Persicaria lapathifolia, Carex kobomugi, and Equisetum arvense, grown in contaminated soil with petroleum and heavy metals. The isolates were screened for plant growth-promoting trait (PGPT), including indole acetic acid (IAA) productivity, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, and siderophore(s) synthesis ability. IAA production was detected in 86 isolates (23.0%), ACC deaminase activity in 168 isolates (44.9%), and siderophore(s) synthesis in 213 isolates (57.0%). Among the rhizobacteria showing PGPT, 162 isolates had multiple traits showing more than two types of PGPT. The PGPT-possesing rhizobacteria were more abundant in the RP (82%) samples than the RS (75%). There was a negative correlation (-0.656, p<0.05) between the IAA producers and the ACC deaminase producers. Clustering analysis by principal component analysis showed that RP was the most important factor influencing the ecological distribution and physiological characterization of PGPT-possesing rhizobacteria.

• Proceedings of the Korean Society of Crop Science Conference
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• 1992.05a
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• pp.58-59
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• 1992

• The Plant Pathology Journal
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• v.36 no.5
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• pp.476-490
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• 2020

The parasitic weed, Orobanche crenata, is one of the most devastating constraint for faba bean production in Mediterranean regions. Plant host defense induction was reported as one of the most appropriate control methods in many crops. The aim of this study was to elucidate the effect of salicylic acid (SA) and indole acetic acid (IAA) on the induction of faba bean resistance to O. crenata under the field and controlled experimental conditions. Both hormones were tested on two contrasting faba bean genotypes: Giza 843 (partially resistant to O. crenata) and Lobab (susceptible) at three different application methods (seed soaking, foliar spray, and the combination of both seed soaking and foliar spray). Soaking seeds in SA or IAA provided the highest protection levels reaching ~75% compared to the untreated control plants. Both elicitors limited the chlorophyll content decrease caused by O. crenata infestation and increased phenolic compound production in host plants. Phenylalanine ammonia lyase, peroxidase, and polyphenol oxidase activities were stimulated in the host plant roots especially in the susceptible genotype Lobab. The magnitude of induction was more obvious in infested than in non-infested plants. Histological study revealed that both SA and IAA decreased the number of attached O. crenata spikes which could be related to specific defense responses in the host plant roots.

• Journal of Microbiology and Biotechnology
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• v.25 no.6
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• pp.903-909
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• 2015

Indole-3-acetic acid (IAA) production is a typical mechanism of plant growth promotion by some rhizobacteria. However, a functional genomic study is necessary to unravel the function and mechanism of IAA signaling during rhizobacteria-plant interactions. In this study, the expression of SlIAA1 and SlIAA9 among the auxin response genes in tomato was examined during the interaction between IAA-producing Acinetobacter guillouiae SW5 and tomato plants. When 3-day grown tomato seedlings were treated for 30 min with 10~100 µM of IAA produced by bacteria from tryptophan, the relative mRNA levels of SlIAA1 and SlIAA9 increased significantly compared with those of the control, demonstrating that IAA produced by this bacterium can induce the expressions of both genes. Inoculation of live A. guillouiae SW5 to tomato seedlings also increased the expressions of SlIAA1 and SlIAA9, with more mRNA produced at higher bacterial density. In contrast, treatment of tomato seedlings with dead A. guillouiae SW5 did not significantly affect the expression of SlIAA1and SlIAA9. When 3-day bacterial culture in tomato root exudates was administered to tomato seedlings, the relative mRNA level of SlIAA1 increased. This result indicated that the plant may take up IAA produced by bacteria in plant root exudates, which may increase the expression of the auxin response genes, with resulting promotion of plant growth.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.6
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• pp.506-512
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• 1991

Monoclonal antibodies (mAb) to indole-3-acetic acid (IAA) were produced and characterized. Spleen cells from mouse immunized with IAA coupled to bovine serum albumin were fused with SP2/0-Ag14 myeloma cells. Three clones secreted specific antibodies to IAA were established to hybridoma cell lines and designated WLI-G1, WLI-G3 and WLI-Ell. The antibodies produced were classified into IgG, types and revealed the high degree of specificity by cross-reaction in the IAA derivatives and its analogues. In the IAA-ELISA with mAb, the measuring range of the assay was 1-500 p mol, and Ka and binding capacity calculated from Scatchard plot were 6.7 X 10$^{-10}$ L/M and 6 x 10$^{-10}$ L/M respectively. The ELISA with mAb can be used to quantitate IAA directly in crude plant eatract. The results showed that the immunoassay was easy and sensitive method to perform and applicate for quantitative analysis of IAA in plant.

• Korean Journal of Environmental Biology
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• v.19 no.4
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• pp.248-253
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• 2001

These studies were carried out to examine the developmental process of galls caused by aphids in Rhus gavanica and the effects of indole-3-acetic acid (IAA) and ${\alpha}$-naphthalene acetic acid (NAA) on the tannin accumulation in the callus induced from that galls. The results are follows. The development of fist-shaped galls has begun at the beginning of June earlier than the case of finger-shaped galls, and also, the growth of fist-shaped galls has last to September longer than the period of finger-shaped galls. These results indicate that the life cycle and feeding activity of the aphids inhabited in fist-shaped galls were longer and mire active than the case of the aphids inhabited in finger-shaped galls. Tannin contents of fist-shaped galls revealed about 60${\sim}70%$ of total dry weights during the whole growth periods, however, the contents in finger-shaped galls were under 10% at the maximum value. These facts mean that finger-shaped galls seem to be as a habitat of aphids rather than as a major source of tannin such as fist-shaped galls. The growth of callus induced from fist-shaped galls was the most effective in the plot of $10^{-5}$ mole IAA, but the tannin accumulation in callus growth was not even caused in any plots of IAA treatments as wells as in any NAA plots. These results considered that the tannin accumulation in fist-shaped galls may be caused only in specific relation between host plant and life cycle of aphids.

• Proceedings of the Ginseng society Conference
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• 1984.09a
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• pp.45-48
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• 1984

Ion-pair reverse phase HPLC techniques were used to compare the contents of IAA and IAAsp in the embryogenic and non-embryogenic calli derived from ginseng (Panax ginseng C.A. Meyer) root tissues. The contents of IAA and IAAsp of the embryogenic callus were much higher (7 to 18 X respectively) than those of non-embryogenic callus. There is a distinct fluorescent peak of an unknown component in the HPLC profile of the extract for indolic compounds from non-embryo-genic callus. This distinct difference may be employed as a promising parameter to screen the culture pieces for obtaining the calli with high potential for embryoid formation.