• Korean Journal of Agricultural Science
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• v.50 no.4
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• pp.759-771
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• 2023

Plant growth-promoting rhizobacteria (PGPR) are naturally occurring bacteria that intensively colonize plant roots and are crucial in promoting the crop growth. These beneficial microorganisms have garnered considerable attention as potential bio-inoculants for sustainable agriculture. PGPR directly interacts with plants by providing essential nutrients through nitrogen fixation and phosphate solubilization and accelerating the accessibility of other trace elements such as Cu, Zn, and Fe. Additionally, they produce plant growth-promoting phytohormones, such as indole acetic acids (IAA), indole butyric acids (IBA), gibberellins, and cytokinins.PGPR interacts with plants indirectly by protecting them from diseases and infections by producing antibiotics, siderophores, hydrogen cyanide, and fungal cell wall-degrading enzymes such as glucanases, chitinases, and proteases. Furthermore, PGPR protects plants against abiotic stresses such as drought and salinity by producing 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase and modulating plant stress markers. Bacteria belonging to genera such as Bacillus, Pseudomonas, Burkholderia, Pantoa, and Enterobacter exhibit multiple plant growth-promoting traits, that can enhance plant growth directly, indirectly, or through synergetic effects. This comprehensive review emphasizes how PGPR influences plant growth promotion and presents promising prospects for its application in sustainable agriculture.

• Korean Journal of Medicinal Crop Science
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• v.13 no.3
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• pp.105-108
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• 2005

Culture conditions for plant regeneration of Camellia japonica were achieved by organogenesis in explants of cotyledon. Seed cotyledons were cultured on MS medium containing various auxin, 2,4-D or NAA and cytokinins BA. The adventitious shoot buds were efficiently formed without embryogenesis on the basal region of cotyledon cultured on MS medium supplemented with $0.1\;{\mu}g/m{\ell}$ 2.4-D and $1\;{\mu}g/m{\ell}$ BA. Seed cotyledons could be used as a source of explants in experiments of genetic transformation of the genotypes evaluated for improving the efficiency of production of transgenic Camellia plants.

• Korean Journal of Plant Tissue Culture
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• v.24 no.1
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• pp.53-55
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• 1997

The shoot tips of Delphinium cv. Princess Caroline were cultured on the MS medium supplemented with cytokinin and auxin alone or in combination. Among cytokinins, BA was most effective in shoot multiplication, adequqte concentrations being 1.0-5.0 mg/L. Shoot multiplication was very favorable on the media with 1.0-3.0 mg/L BA and 0.1-0.5 mg/L IAA. Additions of BA and IAA did not stimulate shoot multiplication, but increased a little fresh weight. Shoots were scarcely rooted on the media with IBA or NAA, and were not done utterly on the media containing activated charcoal. Therefore, shoots were treated by Rootone and planted in the cultural media for in vivo rooting. The highest rate of rooting was 68% in the mixed cultural medium composed of Perlite 1 and Vermiculite 1.

• Plant Biotechnology Reports
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• v.4 no.2
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• pp.139-148
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• 2010

Jatropha curcas L. (Physic nut) is a commercially important non-edible oil seed crop known for its use as an alternate source of biodiesel. In order to investigate the morphogenic potential of immature embryo, explants from four developmental stages were cultured on medium supplemented with combinations of auxins and cytokinins. It was found that the size of embryo is critical for the establishment of callus. Immature embryos (1.1-1.5 cm) obtained from the fruits 6 weeks after pollination showed a good response of morphogenic callus induction (85.7%) and subsequent plant regeneration (70%) with the maximum number of plantlets (4.7/explant) on Murashige and Skoog's (MS) medium supplemented with IBA (0.5 $mg\;l^{-1}$) and BA (1.0 $mg\;l^{-1}$). The above medium when supplemented with growth adjuvants such as 100 $mg\;l^{-1}$ casein hydrolysate + 200 $mg\;l^{-1}$ L-glutamine + 8.0 $mg\;l^{-1}$ $CuSO_4$ resulted in an even higher frequency of callus induction (100%). Plant regeneration (90%) with the maximum number of plantlets (10/explant) was achieved on MS medium supplemented with 500 $mg\;l^{-1}$ polyvinyl pyrrolidone + 30 $mg\;l^{-1}$ citric acid + 1 $mg\;l^{-1}$ BA + 0.5 $mg\;l^{-1}$ Kn + 0.25 $mg\;l^{-1}$ IBA. It was observed that plantlet regeneration could occur either through organogenesis of morphogenic callus or via multiplication of pre-existing meristem in immature embryos. The age of immature embryos and addition of a combination of growth adjuvants to the culture medium appear to be critical for obtaining high regeneration rates. Well-developed shoots rooted on half-halfstrength MS medium supplemented with 0.5 $mg\;l^{-1}$ IBA and 342 $mg\;l^{-1}$ trehalose. The rooted plants after acclimatization were successfully transferred to the field in different agro-climatic zones in India. This protocol has been successfully evaluated on five elite lines of J. curcas.

• Plant Biotechnology Reports
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• v.4 no.2
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• pp.157-163
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• 2010

A protocol for in vitro propagation from pseudobulb sections of Lycaste armomatica (Graham ex Hook) Lindl., an ornamental and fragrant orchid, was developed. The effect of four cytokinins: kinetin (K), metatopolin (mT), $N^6$-benzyladenine (BA), and thidiazuron (TDZ), in equimolar concentrations, was investigated. Shoot formation from apical and basal pseudobulb sections was obtained in all treatments. A few medial sections cultured in media supplemented with BA formed protocorm-like bodies. Shoot formation was greater from the basal section than the apical, and mainly occurred in explants cultured in media containing TDZ. The highest average numbers of shoots per explant were achieved from basal sections cultured in media supplemented with TDZ at 4.4, 8.87 and 2.2 ${\mu}M$, forming on average 9.9, 8.6 and 7.3 shoots per explant, respectively. Since the medial pseudobulb section was the worst explant for propagation of L. aromatica, we recommend that pseudobulbs be divided into two sections; the basal half should be cultured in MS medium supplemented with TDZ at 4.4 ${\mu}M$ and the apical half with TDZ at 2.2 ${\mu}M$. Subculturing individual shoots in MS medium without plant growth regulators allows further development and rooting. A survival rate of more than 90% under greenhouse conditions was achieved. This research represents a direct contribution to the conservation and sustainable use of this valuable natural resource.

• Journal of Plant Biotechnology
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• v.34 no.3
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• pp.189-195
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• 2007

Helicteres isora is medicinally important plant effective against asthma, diabetes, hypolipidemia, HIV, besides a good source of diosgenin. Seed dormancy and low rate of natural fruit production make this plant a perfect candidate for developing an in vitro method useful for its clonal propagation and further biotechnological developments. This is the first report on in vitro production of this plant. Nodal explants obtained from aseptically germinated seedlings were cultured on MS medium (Murashige and Skoog 1962) fortified with indole-3-acetic acid (IAA) ($0.57-22.83\;{\mu}M$), indole-3-butyric acid (IBA) ($0.41-16.58\;{\mu}M$), 6-benzylaminopurine (BA) ($0.44-17.75\;{\mu}M$) and kinetin (Kin) ($0.46-13.94\;{\mu}M$) either singly or in combinations of IAA + BA, IAA + Kin and BA + Kin. Combinations of cytokinins (BA and Kin) were most suitable for multiple shoot induction and $13.94\;{\mu}M\;Kin\;+\;13.31\;{\mu}M\;BA$ was optimum (79% frequency) associated with high number of microshoots (7.1 shoots per explant) after 20 days of culture. Maximum shoot elongation and proliferation (10 shoots per explant with 4.8 cm average height) was achieved on MS media containing $2.32\;{\mu}M\;Kin\;+\;2.22\;{\mu}M\;BA\;+\;2.85\;{\mu}M\;IAA$. High rooting frequency (70%) was achieved on MS medium (1/2 basal strength) fortified with $4.14\;{\mu}M$ IBA, while activated charcoal showed inhibitory effects on rooting. Hardening was done with 76% survival rate and these plants were growing without any visual defects and morphologically mimicking the naturally growing plants.

• Journal of Bio-Environment Control
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• v.17 no.1
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• pp.51-59
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• 2008

Lettuce, a typical light-induced seed germination type, exhibits different germination responses according to cultivars, light quality, and plant growth regulator (PGR) treatments. Germination rates in most tested cultivars were over 85% under both white and red light, and were slightly decreased by blue light. Although photo-inhibition in germination was observed from most cultivars by far-red light, 'Cheongguangcheongchima', 'Okdol', and 'Manchudaecheongchima' could be classified as photo-insensitive lettuce cultivars by exhibiting the germination rates as 78,63, and 48% under for-red light, respectively. 6-Benzylamino purine (BAP) and kinetin promoted seed germination and normal seedling production under far-red light, but ethephon did not show any positive effects. Cytokinins such as BAP, kinetin, thidiazuron (TDZ), and zeatin overcame photo-inhibition of seed germination even the concentration of below $50\;mg{\cdot}L^{-1}$. However, auxins such as IBA, 2,4-D, and NAA failed to overcome the far-red light-induced photo-inhibition.

• Journal of Plant Biotechnology
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• v.31 no.1
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• pp.37-41
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• 2004

In vitro culture system was established to induce multiple shoots of Thymus quinquecostatus Celak. by investigating the effects of cytokinins. Stem explants were cultures on MS medium supplemented with either five drfferent plant growth regulators or their combinations under light or dark condition. The most effective cytokininsource was the combination of BA 1.0mg/L and TDZ 0.1mg/L for producing shoots (6.05$\pm$1.51), zeatin 2.0mg/L and TEZ 0.1mg/L for elongating shoots (3.27$\pm$0.66cm) under the light condition. In addition the most effective cytokinin was 2-ip 2.0mg/L for producing shoots(5.20$\pm$1.81), zeatin 2.0mg/L for elongating shoots(5.64$\pm$1.24cm)under the dark condition. Overall, the average percent for in vitro shooting was greater than 89.58％.

• Applied Biological Chemistry
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• v.35 no.6
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• pp.443-448
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• 1992

To investigate the production of monoterpenoids by Mentha pipperita cells in suspension culture, effects of media formulation, plant growth hormones, initial pH of the media, and cold stress on the production of essential oil and menthol were analyzed. Among the media employed, Lin-Staba medium resulted in the best essential oil production. Addition of 100 mg/l of yeast extract to the Lin-Staba medium induced the cells to produce large amount of essential oil and high content of menthol (0.39 g/l and 19.6%, respectively). In the effect of plant growth hormone, auxine were more effective than cytokinins. At initial pH of 4.7, oil production was good but menthol content was low. However at pH 5.7 the trend was reversed. When the culture temperature was lowered from $27^{\circ}$ to $10^{\circ}$ during 6 hour-dark period, growth was not changed much but essential oil production and menthol content was increased and reached to 528 mg/l and 21%, respectively.

• Korean Journal of Medicinal Crop Science
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• v.13 no.4
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• pp.138-140
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• 2005

This study was carried out to investigate the optimal conditions for efficient in vitro growth of Asparagus cochinchinensis (Lour.) Merr. shoot derived from shoot tip. Shoots were successfully cultured in MS medium. It was found that $23^{\circ}C{\sim}25^{\circ}C$ were suitable for shoot growth. The growth of shoot was greatly influenced by cytokinins. The shoots derived from shoot tip were well elongated on MS medium supplemented with BA and zeatin. In vitro shoots were very poor or no growing. Especially, 3.0 mg/l BA on MS medium was very effective in elongation of shoot. Root formation from in vitro growth of plant let was achieved on MS medium supplemented with 0.5 mg/l IBA. The results suggest that selection of plant growth regulator could be important factor to achieve an efficient in vitro growth.