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1.
Cell division in cell suspension cultures can be completely blocked by the growth retardant tetcyclacis at a concentration of 10-4 mol l-1. In rice cells it has been demonstrated that the growth inhibition can be completely overcome by application of cholesterol independent of the duration of pretreatment with tetcyclacis. In suspension cultures of maize and soybean, too, the effect of tetcyclacis on cell division was neutralized by adding cholesterol. Other plant sterols, stigmasterol, campesterol and sitosterol were active in a decreasing order. Modifications in the cholesterol perhydro-cyclopentanophenanthrene-ring system indicate that the hydroxyl group at C-3 and the double bond between C-5 and C-6 in ring B are required for the activity. In contrast, gibberellic acid as well as ent-kaurenoic acid could not compensate retardant effects. Likewise, tetcyclasis did not change the level of gibberellins in rice cells as shown by radioimmunoassay. Thus, it is concluded that in cell suspension cultures sterols play a more important role in cell division than gibberellins.Abbreviation GAx
gibberelin Ax 相似文献
2.
3.
Gibberellins (GAs) are a group of diterpenoid plant hormones that control plant growth and development at various stages. Biologically active GAs share the common structures of a 3β-hydroxy group, a carboxy group at C-6, and a γ-lactone between C-4 and C-10. Hydroxylation at C-2β is a major deactivation step in many plant species, and hydroxylation at C-13 has been shown to weaken the binding affinity of GAs to their receptor proteins. In rice, bioactive GA4 has also been shown to be deactivated through 16α,17-epoxidation. Moreover, 16,17-dihydro-16α,17-dihydroxy GA4 has been identified as an aglycon of its glucoside from rice. However, our knowledge on the biological activity of 16,17-epoxidized GAs is currently limited to 16,17-dihydro-16α,17-epoxy GA4. Moreover, the bioactivity of 16,17-dihydro-16α,17-dihydroxy GA4 remains unknown. Here, we synthesized 16,17-epoxidized or dihydroxylated GA derivatives and performed a structure–activity relationship study using rice seedlings. 16,17-Epoxidation of bioactive GA1 and GA4 reduced their activity to promote elongation of rice leaf sheaths. Moreover, 16,17-dihydroxylation significantly decreased the activities of 16,17-dihydro-16α,17-epoxy GAs. These results suggest that GAs are deactivated in a stepwise manner via 16,17-epoxidation and hydrolysis of these epoxy groups. 相似文献
4.
Interaction of light and hormone signals in germinating seeds 总被引:1,自引:0,他引:1
Mitsunori Seo Eiji Nambara Giltsu Choi Shinjiro Yamaguchi 《Plant molecular biology》2009,69(4):463-472
Seed germination is regulated by several environmental factors, such as moisture, oxygen, temperature, light, and nutrients.
Light is a critical regulator of seed germination in small-seeded plants, including Arabidopsis and lettuce. Phytochromes,
a class of photoreceptors, play a major role in perceiving light to induce seed germination. Classical physiological studies
have long suggested the involvement of gibberellin (GA) and abscisic acid (ABA) in the phytochrome-mediated germination response.
Recent studies have demonstrated that phytochromes modulate endogenous levels of GA and ABA, as well as GA responsiveness.
Several key components that link the perception of light and the modulation of hormone levels and responsiveness have been
identified. Complex regulatory loops between light, GA and ABA signaling pathways have been uncovered. 相似文献
5.
To develop a new immunological detection system of gibberellins (GAs), a class of phytohormones, peptides that interact with an antibody against GA4 in a GA4-dependent manner, were screened from phage display random peptide libraries. The biopanning procedure yielded peptides designated as anti-metatype peptides (AM-peps), which showed specific binding to the complex of the antibody and its ligand GA4; that is, the antibody could not be replaced with the other anti-GA4 antibody, and GA4 could not be replaced with GA1, another ligand of the antibody. Together with computational analyses such as analysis of structural propensity of the AM-peps and docking simulation of the AM-peps and the 8/E9-GA4 complex, it was suggested that AM-peps formed a helix in their central region and interacted with a part of the 8/E9-GA4 complex located in close proximity to the GA4 molecule. Based on the property of AM-peps to make a ternary complex with antibody and its ligand, a noncompetitive enzyme-linked immunosorbent assay (ELISA) system corresponding to sandwich ELISA was developed to detect GA4. GA4 as low as 30 pg, which could not be achieved by conventional competitive ELISA, could be detected by the new system, demonstrating the feasibility of this system. 相似文献
6.
Tetsushi Azuma Tomoko Hatanaka Naotsugu Uchida Takeshi Yasuda 《Plant Growth Regulation》2003,41(2):105-109
The enhancement of internodal elongation in floating or deepwater rice (Oryza sativa L. cv. Habiganj Aman II) by treatment with ethylene or gibberellic acid (GA3) at high relative humidity (RH) is inhibited by abscisic acid (ABA). Here, we examined the interactive effects of ethylene, gibberellin (GA) and ABA at low RH on internodal elongation of deepwater rice stem segments. Although ethylene alone hardly promoted internodal elongation of stem sections at 30% RH, it enhanced the internodal elongation induced by GA3. Application of ABA alone to stem segments had no effect on internodal elongation. However, in the presence of ethylene and GA3 at 30% RH, ABA further promoted internodal elongation. This promotive effect of ABA was not found in the internodes of stem segments treated either with ethylene or with GA3 at 30% RH or in the internodes of stem segments treated with ethylene and/or GA3 at 100% RH. 相似文献
7.
Kiyohide Kojima Yuichi Tamura Masaru Nakano Dong-sheng Han Yoshiji Niimi 《Plant Growth Regulation》2003,41(2):99-104
The levels of indole-acetic acid (IAA), gibberellic acid1 (GA1), trans-zeatin (Z) and trans-zeatin riboside (ZR) in seedless fruits of parthenocarpic tomato (Lycopersicon esculentum Mill. cv. Rarkuna First) were analysed using 13C6-IAA, 2H2-GA1, 2H5-Z and 2H5-ZR, as internal standards by liquid chromatography–mass spectrometry. Fruits were sampled at 6 cm in diameter (referred to as 6-cm-fruit) and 8 cm (8-cm-fruit, mature green stage) and separated into pericarps, partitions and locule tissues. The pericarps and partitions were centrifuged for the collection of apoplast (AP) solution (sap outside a cell) and symplast (SP) solution (sap within a cell). IAA concentrations of the pericarps and partitions were higher in 8-cm-fruit than in 6-cm-fruit. In the partitions, IAA concentrations of SP solution were higher than those of AP solution in both 6- and 8-cm-fruit. The SP solution of the partitions in 6-cm-fruit had the highest concentration of Z (4.6 pmol/g fresh weight) and was 2.7 times than the AP solution, while in the pericarps Z concentrations were the same level in AP and SP solution. The ZR concentration in locule tissues in 6-cm-fruit (55 pmol/g fresh weight ) was the highest of all parts. The results suggest that the sites of synthesis may be the SP of partitions for IAA and Z, and locules for ZR. 相似文献
8.
Dormant, intact Avena fatua L. (wild oat) seeds germinate poorly at 20 °C. Removing the hulls slightly increased germination. Treatment with smoke solutions
increased the germination of both intact seeds and caryopses. Exogenous GA3, alone or in the presence of smoke solution, increased the germination of caryopses, while ACC shows a tendency to increase
germination of caryopses only when applied in combination with smoke solution. Results suggest that GA3 and ethylene, but not smoke solutions, are involved in the regulation of α-amylase activity during germination. However,
the participation of smoke solutions in the control of ACC oxidase activity cannot be excluded. 相似文献
9.
10.
Marilyn M. G. Johnstone Dennis M. Reinecke Jocelyn A. Ozga 《Journal of Plant Growth Regulation》2005,24(3):214-225
This study explores the unique growth-regulatory roles of two naturally occurring auxins, indole-3-acetic acid (IAA) and 4-chloroindole-3-acetic
acid (4-Cl-IAA), and their interactions with gibberellin (GA) during early pea (Pisum sativum L.) fruit development. We have previously shown that 4-Cl-IAA can replace the seed requirement in pea pericarp growth (length
and fresh weight), whereas IAA had no effect or was inhibitory. When applied simultaneously, gibberellin (GA3 or GA1) and 4-Cl-IAA had a synergistic effect on pericarp growth. In the present study, we found that simultaneous application of
IAA and GA3 to deseeded pericarps inhibited GA3-stimulated growth. The inhibitory effect of IAA on GA-stimulated growth was mimicked by treatment with ethephon (ethylene
releasing agent), and the inhibitory effects of IAA and ethylene on GA-mediated growth were reversed by silver thiosulfate
(STS), an ethylene action inhibitor. Although pretreatment with STS could retard senescence of IAA-treated pericarps, STS
pretreatment did not lead to IAA-induced pericarp growth. Although 4-Cl-IAA stimulated growth whereas IAA was ineffective,
both auxins induced similar levels of ethylene evolution. However, only 4-Cl-IAA-stimulated growth was insensitive to the
effects of ethylene. Gibberellin treatment did not influence the amount of ethylene released from pericarps in the presence
or absence of either auxin. We propose a growth regulatory role for 4-Cl-IAA through induction of GA biosynthesis and inhibition
of ethylene action. Additionally, ethylene (IAA-induced or IAA-independent) may inhibit GA responses under physiological conditions
that limit fruit growth. 相似文献