• Journal of Plant Biology
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• 제34권2호
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• pp.159-163
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• 1991

합성 식물생장조절제인 dimethipin의 작용기작을 밝히고자 보리 무배부 종자 시스템에서 gibberellic acid(GA3)에 의해 유도되는 ${\alpha}-amylase$ 활성에 미치는 dimethipin의 영향을 조사하였다. Dimethipin은 mRNA와 단백질 함량 및 GA3에 의해 유도되는 ${\alpha}-amylase$ 활성을 뚜렷하게 억제하였다. 그러나 억제효과는 GA3 처리 후 dimethipin 첨가시간 간격이 커질수록 점점 감소하였다. Dimethipin을 GA3 처리후 18시간 이내에 첨가하였을 때 mRNA 함량증가를 억제하였다: 그러나 GA3 처리 18시간 경과 후에 첨가하였을 경우에도 수용성 단백질 함량 및 ${\alpha}-amylase$ 활성 증가를 억제하였다. 이러한 결과로 미루어보아 dimethipin은 mRNA 합성과 ${\alpha}-amylase$ 단백질 합성을 공히 억제하는 것으로 사료된다.

• 한국작물학회지
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• 제25권1호
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• pp.20-24
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• 1980

Seven different rice cultivars treated with different levels of gibberellic acid (0, 10, 50 and 100 PPM GA3) at panicle initiation stage. showed retardation effect on the panicle length and the 2nd internode from the top, where as, the total culm lengths were remarkably elongated, about 50-120% in short varieties and about 10-15% in the tall varieties over the control, mainly, because of the lower internodes elongation. The 2nd internode of Gamadi variety from Nepal was almost entirely shortened with GA3 application.

• Journal of Plant Biology
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• 제22권4호
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• pp.95-100
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• 1979

As a part of the studies on the regulatory mechanism of gene expression by $GA_{3}$ , the effects of $GA_{3}$ on the protein biosynthesis and phosphorylation in maize seedlings were investigated. 1. The optimum concentration of $GA_{3}$ for the stimulation of the protein biosynthesis was 0.3mM. 2. The protein biosynthesis was remarkably increase by $GA_{3}$ during the germination. The reason for the decrease in the protein biosynthesis by 48hrs. after germination seems to be a staggered gene expression, and/or increases in protease and RNase activities. 3. The ratio of the amount of the newly synthesized protein in germinating seeds treated with $GA_{3}$ to the amount of proteins secreted into the endosperm was similar to that ratio in control. According to this result, it seems that $GA_{3}$ stimulates only the expression of certain definite genes. 4. By the treatment with $GA_{3}$, the rates of biosynthesis and phosphorylation of proteins were increased up to about 1.5 times during germination and 6 times by 72hrs. after germination, respectively. The ratio of the total soluble proteins to the phosphorpoteins considerably increased in the early germination stage (24hrs.) but decreased after 24hrs. According to the above mentioned results, the stimulation of the phosphorylation of proteins of $GA_{3}$ seems to be attributed to the increases in the activities of protein kinases.

• Biotechnology and Bioprocess Engineering:BBE
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• 제8권5호
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• pp.269-278
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• 2003

Gibberellic acid (GA$_3$) is a commercially important plant growth hormone, which is gaining much more attention all over the world due to its effective use in agriculture and brewing industry. Industrially it is produced by submerged fermentation technique using Ascomycetous fungus Gibberella fujikuroi. Solid state and immobilized cell fermentation techniques had also been developed as an alternative to obtain higher yield of GA$_3$. This review summarizes the problems of GA$_3$ fermentation such as production of co-secondary metabolites along with GA$_3$, substrate inhibition and degradation of GA$_3$ to biologically inert compound gibberellenic acid, which limits the yield of GA$_3$ in the fermentation medium. These problems can be overcome by various bioprocessing strategies e.g. two - stage and fed batch cultivation processes. Further research on bioreactor operation strategies such as continuous and / or extractive fermentation with or without cell recycle / retention system need to be investigated for improvement in yield and productivity. Down stream processing for GA$_3$ isolation is also a challenge and procedures available for the same have been critically evaluated.

• Journal of Plant Biology
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• 제25권1호
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• pp.3-8
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• 1982

As a part of the studies on the regulatory mechanism of gene expression by gibbrellic acid, the effects of $GA_3$ on the protein biosynthesis and phosphorylation in maize seedlings were investigated in the presence of actinomycin D. The activities of protein biosynthesis and phosphorylation in germinating seeds treated with $GA_3$ were greater than those of the control at the 3-day point after germination. It is assumed that the enhancement of protein biosynthesis by $GA_3$ in the presence of actinomycin D is due to the effects of $GA_3$ on the translational processes in which protein is produced from the mRNA synthesized previously.

• Journal of Plant Biology
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• 제20권2호
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• pp.91-101
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• 1977

Using barley seeds (Hordeum sativum Jess, var.), the influences of gibberellic acid (GA) and indole-3-acetic acid(IAA) on the amylase synthesis and that of the nucleic acid metabolism were investigated. 1. With the deembrynized barley seeds, the increase of amylase treated with a $10^{-5}M$ of GA and the decrease of amylase treated with $10^{-5}M$IAA were matched by a proportionate increase and decrease in the amount of RNA. The influence of the hormones on the RNA synthesis has appeared immediately after the treatment but on the amylase synthesis it has appeared 8 hours later. But no influence on the DNA synthesis was observed on both hormones. 2. The amylase from deembryonized barley seeds treated with GA and IAA have been fractionated by gel filteration on Sephadex G-100. The amylase components showed four fractions on both enzymes treated with GA and IAA. Fraction I(FI) was differed from fraction Ⅵ(FIV) in Km value and the effects of temperature, pH and metal ions. On the basis of their emzymatic properties, it was considered that the FI was $\beta$-amylase and FIV was $\alpha$-amylase. The influences of GA and IAA on each fractions appeared to be similar but on the amylase units per souble protein, IAA inhibited the production of amylase FIV while it promoted that of amylase FI. 3. An experiment was conducted to determine whether IAA inhibits GA-promoted amylase synthesis competitively or non-competitively. Using a Lineweaver-Burk plot, it was clear that IAA was acting in a non-competitive fashion. From this, IAA was probably not competing with GA at the same site, but it was acting at some other site which resutled in partial blocking of the action of GA on the amylase synthesis.

• Journal of Plant Biology
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• 제31권4호
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• pp.249-258
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• 1988

Changes in starch content and activities of ADPG- and UDPG-starch synthase and $\alpha$- and, $\beta$-amylase were studied in order to investigate effects of gibberellic aicd and abscisic acid on endogenous starch content during shoot differentiation and protocorm propagation in Cymbidium spp. (Jungfrau) protocorm. Shoot differentiation was promoted during the degradation of endogenous starch and protocorn propagation was promoted during starch accumulation in protocorm. The activities of ADPG- and, UDPG-starch synthase and $\alpha$- and $\beta$-amylase seemed to be related with starch content. Shoot differentiation and protocorm propagation were slightly inhibited in protocorm explants treated with 100$\mu$M gibberellic acid. The explants treated with 10$\mu$M abscisic acid lost the capacity for shoot differentiation and protocorm propagation, and that could not be overcome by 100$\mu$M gibberellic acid added to culture medium. Starch content fluctuated as the control even after 10$\mu$M abscisic acid. None the less, the treatment completely inhibited shoot differentiation and protocorm propagation.

• 생물환경조절학회지
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• 제24권1호
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• pp.27-33
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• 2015

토마토의 착과와 수확량은 여름철 비닐하우스내 고온스트레스로 인하여 감소하게 된다. 본 연구는 여름철 화천지역에 위치한 비닐하우스에서 지베렐린($GA_3$)과 2,4-Dichlorophenoxy Acetic Acid(2,4-D) 처리가 토마토의 수확량, 착과율, 착과 후 과실품질에 미치는 영향을 알아보기 위해 'Adoration' 품종을 이용하여 실험하였다. $GA_3$ 0-, 5-, 10-, $15mg{\cdot}L^{-1}$와 2,4-D 0-, 5-, $10mg{\cdot}L^{-1}$를 개화 초기에 처리한 후 착과율, 수확량, 과실품질과 관련된 형질을 관찰한 결과, $GA_3$ $10mg{\cdot}L^{-1}$처리구에서 대조구에 비해 14.2%의 착과율 증가를 보였다. $GA_3$처리구에서는 수확량, 과중, 상품과실 수에 유의한 차이가 있었다. 2,4-D를 개화기에 처리했을 경우 착과율, 수확량, 상품과의 과중에 영향을 미쳤으며 $GA_3$과 2,4-D를 각각 $5mg{\cdot}L^{-1}$ 농도로 혼합처리 하였을 때 가장 높은(62.5%) 착과율을 나타내었다. 과실크기와 고형물함량은 $GA_3$처리구에서만 유의성 있는 차이를 보였다. 따라서 여름철 비닐하우스의 고온조건에서 $GA_3$ $0mg{\cdot}L^{-1}$처리구와 2,4-D $5mg{\cdot}L^{-1}$를 처리했을 때 착과율이 가장 높아 많은 수확량을 기대할 수 있을 것으로 판단된다.

• 한국약용작물학회지
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• 제17권4호
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• pp.238-242
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• 2009

Somatic embryos on growth regulator-free medium can be produced directly from cotyledon explants of Panax ginseng C. A. Meyer. When the embryo developmental stage was torpedo and cotyledon, the germination rate of embryos was quite high on MS medium supplemented with gibberellic acid ($GA_3$). However, the percentage of plantlet formation at the cotyledon stage was higher than that at the torpedo stage. This result demonstrates that the embryo at the cotyledon stage was the most appropriate for increasing germination by $GA_3$. Embryos cultured on medium including four levels of $GA_3$ concentrations (3, 5, 10, or 20 mg/$\ell$) showed all quite high germination rates (87-91%). When the well-developed embryos were continuously cultured on media including high concentrations of $GA_3$ from 10 to 20 mg/$\ell$, the percentage of formation of normal plantlets was lower than that seen under low concentrations from 3 to 5 mg/$\ell$. This treatment of high concentrations resulted in shoots with abnormal shape. The optimal $GA_3$ treatment provides a basis for the efficient method obtaining healthy plantlets derived from ginseng somatic embryos.

• 농약과학회지
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• 제2권3호
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• pp.107-116
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• 1998

Gibberellic acid에 대한 밀과 메귀리간에 차등반응을 이용하여 제초제에 gibberellic acid를 첨가함으로써 상대적으로 민감한 반응을 보였던 메귀리를 효과적으로 방제할 수 있는 조합을 찾고, 그 효과증대의 생리적 원인을 조사하고자 실험하였다. 밀은 $GA_{3}$에 대한 낮은 신장반응을 보였으나, 메귀리는 이보다 $4{\sim}5$배 높은 반응을 보였다. $GA_{3}$에 침지된 메귀리 종자를 파종한 후 토양처리했을 때는 isoproturon, trifluralin의 효과가 증진되었다. 경엽처리의 경우 $GA_{3}$는 tralkoxydim fenoxaprop-ethyl, metsulfuron-methyl, metribuzine, isoproturon의 효과를 증진시켰으나, oxyfluofen과 paraquat의 효과에는 거의 영향을 미치지 않았다. 경엽처리조건에서 체계처리를 할 경우 tralkoxydim처리 이전에 $GA_{3}$를 처리하면 tralkoxydim의 효과를 증진시켰으나, tralkoxydim처리 이후에 $GA_{3}$를 처리하면 효과가 낮은 경향이었다. 그러나 $GA_{3}$를 어느 시기에 처리하여도 tralkoxydim의 신장저해효과를 증진 또는 경감시키지는 못하였고, $GA_{3}$가 처리된 잎의 과산화작용 화합물에 대한 반응은 무처리와 비교하여 일정한 경향을 보이지 않았다. 이들 결과로 보아 $GA_{3}$가 일부 제초제의 효과를 증진시킨 것은 조직의 연화(세포신장 촉진)에 의한 높은 제초반응 때문이라기보다는 제초제 흡수, 이행의 변화 또는 제초작용 발현과 관련한 체내대사의 촉진 때문으로 추정된다.