• Journal of Microbiology
• /
• v.43 no.6
• /
• pp.510-515
• /
• 2005

The growth of red pepper plants was enhanced by treatment with the rhizobacterium, Bacillus cereus MJ-1. Red pepper shoots showed a 1.38-fold increase in fresh weight (fw) and roots showed a 1.28-fold fw gain. This plant growth-promoting rhizobacterium (PGPR) has been reported to produce gibberellins (GAs). Other GAs-producing rhizobacteria, Bacillus macroides CJ-29 and Bacillus pumilus CJ-69, also enhanced the fw of the plants. They were less effective than B. cereus MJ-1, though. The endogenous GAs content of pepper shoots inoculated with MJ-1 was also higher than in shoots inoculated with CJ-29 or CJ-69. When inoculated with MJ-1, bacterial colonization rate of the roots was higher than that of roots inoculated with CJ-29 or CJ-69. These results support the idea that the plant growth-promoting effect of the bacteria also positively related with the efficiency of root colonization by the bacteria. In addition, we identified the major endogenous GAs of the red pepper as originating from both the early C-13 hydroxylation and the early non C-13 hydroxylation pathways, with the latter being the predominant pathway of GA biosynthesis in red pepper shoots.

• The Korean Journal of Mycology
• /
• v.32 no.1
• /
• pp.16-22
• /
• 2004

The gibberellins (GAs) play important roles in plant growth and development. Twenty three fungi were isolated from the roots of Lindera obtusiloba and Vaccinium koreanum. The numbers of GA-producing fungi were six strains from Lindera obtusiloba and four strains from Vaccinium koreanum. The fungi with GAs-producing activity were incubated for seven days in 40 ml of Czapek's liquid medium at $25^{\circ}C$, 120 rpm, and the amount of each GA in the medium was measured by gas chromatography-mass spectrometer (GC-MS) to determine the productivity of GAs. Penicillium griseofulvum KNU5379 produced more GA in case of $GA_{3}$ than Neurospora crassa known as a GAs-producing fungus. P. griseofulvum KNU5379 was shown to produce $GA_1\;9.79\;ng,\;GA_3\;133.58\;ng,\;GA_4\;2.64\;ng,\;GA_7\;7.80\;ng\;and\;GA_{53}\;0.73\;ng$ in 25 ml of liquid medium. Bioassay using culture fluid of GAs-production fungi was performed on rice sprout.

• Journal of Crop Science and Biotechnology
• /
• v.11 no.4
• /
• pp.223-226
• /
• 2008

Seedlings of two rice cultivars i.e. cv. Daesanbyeo and cv. Dongjinbyeo were analyzed for growth and endogenous gibberellins (GAs) in response to nitrogen nutrition applied in the forms of $KNO_3$, $(NH_4)_2SO_4$ and $NH_4NO_3$. All the growth parameters showed an increase in N applied treatments and their magnitudes of increase were different depending on different nitrogen fertilizer forms. The endogenous GAs contents were increased with N application but differentially affected by various N-forms in both rice cultivars. In cv. Daesanbyeo, maximum amount of bioactive $GA_1$ was recorded for $(NH_4)_2SO_4$, while maximum amount of bioactive $GA_1$ in cv. Dongjinbyeo was observed in $NH_4NO_3$ applied treatments. In both rice cultivars, $KNO_3$ applied rice plants contained least $GA_1$ contents. Also, $GA_{19}$ was the most abundant GA found in rice seedlings whereas $GA_4$ was absent at seedling stage. Our study indicated that different rice cultivars showed different responses for the same fertilizer depending upon the response potential of each cultivar and the pertinent physiological responses to changes of endogenous GAs in rice cultivars, which were comparatively lesser in magnitude.

• Microbiology and Biotechnology Letters
• /
• v.35 no.4
• /
• pp.357-363
• /
• 2007

249 fungal strains were isolated from the roots of 26 plants, and the production of GAs was spectrophotometric ally examined. As a result 76 fungal strains were shown to produce GAs. Bioassay of culture broth from seventy six fungal strains producing GAs was carried out with waito-c rice, that is dwarf rice. The seventy six fungi with GAs-producing activity were incubated for seven days in 40 mL of Czapek's liquid medium at $30^{\circ}C$ and 180 rpm, and the culture broth of fungi were treated on the 2-leaf rice sprout. Fifteen of these showed plant growth promoting activity and the amount of each GAs in the medium was measured by Gas chromatographymass spectrometer (GC-MS). Nine of these fungi were also identified by genetic analysis of the nucleotide sequences in the internal transcribed spacer region of the ribosomal DNA.

• Journal of Microbiology and Biotechnology
• /
• v.15 no.1
• /
• pp.22-28
• /
• 2005

Gibberellins (GAs) play important roles in plant growth and development. Fifty-four fungi were isolated from the roots of 4 kinds of Sesamum indicum plants, and the production of GAs was spectrophotometrically examined. The number of GA-producing fungi was two strains from S. indicum, four strains from Gold S. indicum, and five strains from Brown S. indicum. Eleven fungi with GAs-producing activity were incubated for seven days in 40 ml of Czapek's liquid medium at $25^{\circ}C$ and 120 rpm, and the amount of each GA in the medium was measured by gas chromatographymass spectrometery (GC-MS). Penicillium commune KNU5379 produced more $GA_3$, $GA_4$, and $GA_7$ than Gibberella fujikuroi, Fusarium proliferatum, and Neurospora crassa which are known as GAs-producing fungi. GAs-producing activity of the P. commune KNU5379 was shown to produce 71.69 ng of $GA_1$, 252.42 ng of $GA_3$, 612.00 ng of $GA_4$, 259.00 ng of $GA_7$, and 202.69 ng of $GA_9$ in 25 ml of liquid medium. Bioassay of culture fluid of GA-producing fungi was also performed on rice sprout.

• Mycobiology
• /
• v.43 no.1
• /
• pp.87-91
• /
• 2015

Eighteen endophytic fungi with different colony morphologies were isolated from the roots of Nymphoides peltata growing in the Dalsung wetland. The fungal culture filtrates of the endophytic fungi were treated to Waito-c rice seedling to evaluate their plant growth-promoting activities. Culture filtrate of Y2H0002 fungal strain promoted the growth of the Waito-c rice seedlings. This strain was identified on the basis of sequences of the partial internal transcribed spacer region and the partial beta-tubulin gene. Upon chromatographic analysis of the culture filtrate of Y2H0002 strain, the gibberellins (GAs: $GA_1$, $GA_3$, and $GA_4$) were detected and quantified. Molecular and morphological studies identified the Y2H0002 strain as belonging to Aspergillus clavatus. These results indicated that A. clavatus improves the growth of plants and produces various GAs, and may participate in the growth of plants under diverse environmental conditions.

• Journal of Microbiology and Biotechnology
• /
• v.20 no.12
• /
• pp.1744-1749
• /
• 2010

The role of endophytic fungi in plant growth and development is well documented. However, endophytic fungi with growth promotion capacity have never been isolated from weeds previously. In the current study, we isolated 8 fungal endophytes from the roots of Monochoria vaginalis, a serious weed of rice paddy in Korea. These isolates were screened on Waito-C, in order to identify plant growth promoting metabolites. Two fungal isolates (M5.A & M1.5) significantly promoted the plant height and shoot length of Waito-C during preliminary screening experiments. The culture filtrates (CFs) of M5.A and M1.5 also promoted the shoot length of Echinocloa crusgalli. Gibberellins (GAs) analysis of the CFs of M5.A and M1.5 showed that these endophytic fungi secrete higher quantities of GAs as compared with wild-type G. fujikuroi KCCM12329. The CF of M5.A contained bioactive GAs ($GA_3$, 2.8 ng/ml; $GA_4$, 2.6 ng/ml, and $GA_7$, 6.68 ng/ml) in conjunction with physiologically inactive $GA_9$ (1.61 ng/ml) and $GA_{24}$ (0.18 ng/ml). The CF of M1.5 contained physiologically active GAs ($GA_3$, 1.64 ng/ml; $GA_4$, 1.37 ng/ml and $GA_7$, 6.29 ng/ml) in conjunction with physiologically inactive $GA_9$ (3.44 ng/ml), $GA_{12}$ (0.3 ng/ml), and $GA_{24}$ (0.59 ng/ml). M5.A and M1.5 were identified as new strains of Penicillium sp. and Aspergillus sp., respectively, based on their 18S rDNA sequence homology and phylogenetic analysis.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.48 no.2
• /
• pp.68-72
• /
• 2003

The metabolism of [$^{14}\textrm{C}$] $\textrm{GA}_{12}$ in the Chinese yam (Dioscorea opposita Thunb. var. Tsukune) was examined to determine the identification of endogenous gibberellins. [$^{14}\textrm{C}$] $\textrm{GA}_{12}$ was metabolized to $\textrm{GA}_{53}$, $\textrm{GA}_{44}$, $\textrm{GA}_{19}$, $\textrm{GA}_{20}$, $\textrm{GA}_1$, $\textrm{GA}_8$, $\textrm{GA}_{15}$, $\textrm{GA}_{24}$, $\textrm{GA}_9$, $\textrm{GA}_{36}$ and $\textrm{GA}_4$. Radioactivity of GAs in non C-13 hydroxylation route was five-fold higher than that of early C-13 hydroxylation in analyzed GA-metabolites. Radioactivity of $\textrm{GA}_4$ was always four times higher than that of $\textrm{GA}_1$ at every feeding time. $\textrm{GA}_1$ radioactivity has always a lower level to below 200 DPM. The major pathway of endogenous GA metabolism in seedlings of the Chinese yam might be the non C-13 hydroxylation pathway.

• Journal of Crop Science and Biotechnology
• /
• v.10 no.4
• /
• pp.281-286
• /
• 2007

Gibberellins are growth hormones that play a pivotal role in the growth and development of plants. Present investigations were carried to check the effect of nitrogen(N) and silicon(Si) on bioactive $GA_1$ and its immediate precursor $GA_{20}$ at different growth stages of two rice cultivars with different maturity traits. It was observed that the endogenous bioactive $GA_1$ level gradually increased during vegetative stage and anthesis stage of both Junghwabyeo(early flowering cultivar) and Daesanbyeo(late flowering cultivar). However, the $GA_1$ and $GA_{20}$ content start decreasing during the seed filling stage in both rice cultivars, which indicated a possible relationship of bioactive $GA_1$ and floral development. Our results also confirmed that early 13-hydroxylation pathway was operated at all developmental stages of rice plant. Variation in the levels of the endogenous gibberellins in rice shoots were measured by GCMS-SIM using $^2H_2$-labeled gibberellins as internal standards. Combined application of N and Si enhanced growth parameters and reduced lodging index of both rice cultivars. It was thus concluded that the level of physiologically active $GA_1$ increased during vegetative and early reproductive stage, but starts declining at seed filling stage.

• Journal of Crop Science and Biotechnology
• /
• v.10 no.1
• /
• pp.45-49
• /
• 2007

Silicon is one of the key elements for healthy growth and development in rice crops. We analyzed the effect of silicon(Si) on some growth parameters, plant mineral contents, and bioactive gibberellins in three rice cultivars. Silicon was applied at the rates of 0 kg/0.1ha(control), 40 kg/0.1ha, and 80 kg/0.1ha throughout the course of experiment. Plant growth parameters were enhanced by the application of elevated Si, though plant height and culm length were more favorably affected than the respective dry weights. The plant mineral contents analyzed also increased in treatments where Si was applied without potassium, demonstrating that Si application promotes the absorption of these minerals in rice crops. The endogenous gibberellins measured in our study showed that $GA_1$ is the only bioactive GA form present in rice seedlings. The endogenous $GA_1$ and its precursor $GA_{20}$ contents increased after Si application. However, this increase in endogenous $GA_1$ and $GA_{20}$ contents, and plant growth parameters were different according to the rice cultivars. Our results indicate that Si is a beneficial element in rice nutrition and that different cultivars of Oryza sativa show differential responses to Si nutrition in terms of their growth and development.