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1.
Yoshikatsu Matsubayashi Akiko Morita Emi Matsunaga Akiko Furuya Nobuo Hanai Youji Sakagami 《Planta》1999,207(4):559-565
The aim of this research was to determine whether the production of the mitogenic peptide, phytosulfokine-α (PSK-α), is affected
by auxin and/or cytokinin, and whether the expression of the biological activity of PSK-α requires the presence of these plant
hormones. We developed a competition enzyme-linked immunosorbent assay system that measures the amount of PSK-α using a polyclonal
antibody. In suspension-cultured mesophyll cells of Asparagus officinalis L., the production of PSK-α was first detected after 48 h of culture, prior to the first cell division which was generally
observed after 96 h of culture when both 1-napthaleneacetic acid and N6-benzyladenine were present in the medium. No significant amount of PSK-α was, however, produced when one of these plant hormones
was eliminated from the medium. We also characterized the progression of the cell cycle triggered by PSK-α using a fluorescent
dye and microdensitometry. Asparagus mesophyll cells immediately after isolation were arrested in G0/G1, and the cell cycle proceeded only when all three factors, 1-naphthaleneacetic acid, N6-benzyladenine, and PSK-α, existed in the medium. These results show that the production and the expression of biological
activity of PSK-α is closely correlated with the signal transduction pathway mediated by auxin and cytokinin.
Received: 26 June 1998 / Accepted: 11 November 1998 相似文献
2.
3.
In excised pith parenchyma from Nicotiana tabacum L. cv. Wisconsin Havana 38, auxin (naphthalene-1-acetic acid) together with cytokinin (6-benzylaminopurine) induced a greater than 40-fold increase in a p34cdc2-like protein, recoverable in the p13suc1-binding fraction, that had high H1 histone kinase activity, but enzyme induced without cytokinin was inactive. In suspension-cultured N. plumbaginifolia Viv., cytokinin (kinetin) was stringently required only in late G2 phase of the cell division cycle (cdc) and cells lacking kinetin arrested in G2 phase with inactive p34cdc2-like H1 histone kinase. Control of the Cdc2 kinase by inhibitory tyrosine phosphorylation was indicated by high phosphotyrosine in the inactive enzyme of arrested pith and suspension cells. Yeast cdc25 phosphatase, which is specific for removal of phosphate from tyrosine at the active site of p34cdc2 enzyme, was expressed in bacteria and caused extensive in-vitro activation of p13suc1-purified enzyme from pith and suspension cells cultured without cytokinin. Cytokinin stimulated the removal of phosphate, activation of the enzyme and rapid synchronous entry into mitosis. Therefore, plants can control cell division by tyrosine phosphorylation of Cdc2 but differ from somatic animal cells in coupling this mitotic control to hormonal signals.Abbreviations BAP
6-benzylaminopurine
- BrdUrd
5-bromo-2-deoxyuridine
- cdc
cell division cycle
- Cdc25
cdc phospho-protein phosphatase
- CKI
cyclin dependent kinase inhibitor
- 2,4-D
2,4-dichlorophenoxyacetic acid
- DAPI
4,6 diamidino-2-phenylindole
- GST-cdc25
glutathione sulfur transferase-truncated cdc25 fusion
- MS
Murashige and Skoog (1962)
- NAA
naphthalene-1-acetic acid
- p34cdc2
34-kDa product of the cdc2 gene 相似文献
4.
Medicago truncatula, a model for legume genomics, can be regenerated by somatic embryogensis by the use of a suitable genotype and an auxin plus cytokinin. The stress response induced by explant wounding and culture is increasingly recognized as an important component of somatic embryo induction. We have cloned and investigated the stress kinase gene MtSK1 in relation to somatic embryogenesis in M. truncatula, using the highly embryogenic mutant Jemalong 2HA (2HA) and its progenitor Jemalong. The main features of the MtSK1 protein of 351 amino acids are an N-terminal kinase domain and a C-terminal glutamic acid-rich region, which is predicted to be a coiled-coil. MtSK1 is a member of the SnRK2 subgroup of the SnRK group of plant kinases. Members of the SnRK2 kinases play a role in stress responses of plants. MtSKI expression is induced by wounding in the cultured tissue independent of auxin or cytokinin. However, in both 2HA and Jemalong, as the callus develops in response to auxin plus cytokinin, MtSK1 expression continues to increase. MtSK1 responds to salt stress in vivo, consistent with its role as a stress kinase. The likely role of MtSK1 in stress-induced signaling will facilitate the relating of stress–response pathways to auxin and cytokinin-induced signaling in the understanding of the molecular mechanisms involved in the induction of somatic embryogenesis in M. truncatula. 相似文献
5.
External application of auxin and cytokinin is required for the formation of flower buds on thin-layer tissue explants of Nicotiana tabacum cv Samsun. Interaction between both plant growth regulators during this regenerative process has been demonstrated with respect to speed of flower bud initiation and the number of flower buds formed. Separation in time of the hormone application during culture revealed that the cytokinin benzyladenine plays a key role in flower bud initiation whereas auxin (indoleacetic acid) stimulates in particular the differentiation of flower buds. The uptake of each hormone was proportional to the concentration supplied in the medium, and the uptake of either hormone appeared independently of the presence of the other. Metabolism studies showed the conversion of indoleacetic acid by the tissue to at least 13 metabolites after 24 h of culture. In addition, indoleacetic acid metabolism was demonstrated not to be influenced by the uptake and metabolism of benzyladenine. Taken together the results indicate that the interaction of auxin and cytokinin with respect to in vitro flower bud formation is indirect, i.e. does not take place at the level of hormone uptake or metabolism but at some step in the cascade of processes they initiate. 相似文献
6.
7.
Effects on growth, mostly of an inhibitory nature, have been attributed to phenolic compounds in vivo and in vitro. This
suggests that l-α-aminooxy-β-phenylpropionic acid (l-AOPP), a competitive inhibitor of phenylalanine ammonia-lyase (PAL), the enzyme controlling the first step in phenylpropanoid
synthesis, might stimulate growth in soybean suspension cultures (Glycine max, cv. Acme). The promotive effect of l-AOPP, measured as an increase in cell number, was more clearly detected in the growth-limiting condition of cytokinin starvation.
At least one more cell division cycle was completed in the presence of l-AOPP before growth by division ceased and growth continued by expansion only. Phenolic acids are known to conjugate with
polyamines, modulating the free levels of these plant growth substances. Thus, the effect of l-AOPP on the titers of free and conjugated polyamines (putrescine, spermidine, and spermine) was investigated by high performance
liquid chromatography in the course of cytokinin starvation. An increased level of free putrescine was detected in the presence
of l-AOPP relative to controls, especially in the initial period before growth became restricted to cell expansion. The decrease
in free putrescine associated with the cessation of cell division was temporarily delayed, suggesting that an interaction
between phenolic acids and polyamines is involved in the mechanism of growth promotion by l-AOPP.
Received July 30, 1996; accepted January 28, 1997 相似文献
8.
Shoot initiation and development was observed in Catasetum (Orchidaceae) cultured on hormone-free media. Endogenous auxin and cytokinin contents were determined in excised root tips
of two Catasetum fimbriatum genotypes incubated in a hormone-free medium. During the culture period, significant accumulation of all measured cytokinins
was observed in the isolated root tips of both genotypes, reducing, by the 10th day of incubation, the auxin/cytokinin ratio
tenfold in both genotypes. Root excision and the competence for shoot development in C. fimbriatum may be attributable to the establishment of an endogenous auxin/cytokinin ratio favoring cytokinins.
Received: 20 August 1998 / Revision received: 30 January 1999 / Accepted: 15 February 1999 相似文献
9.
H. R. Irving G. Dyson R. McConchie R. W. Parish C. A. Gehring 《Journal of Plant Growth Regulation》1999,18(2):93-100
The effects of jasmonic acid (JA) on elongation growth of coleoptile segments from etiolated maize (Zea mays L.) were investigated in the presence and absence of auxin. When supplied alone, at physiological concentrations (10−9, 10−8, and 10−5
m), JA (or methyl-JA) inhibited growth. JA at a similar range of concentrations also inhibited auxin-induced elongation growth.
To determine whether this effect on growth depended on endogenous abscisic acid (ABA), we grew maize coleoptiles in the presence
of norflurazon (an inhibitor of carotenoid biosynthesis) that results in reduced endogenous ABA levels. Growth of etiolated
coleoptile segments from these plants was inhibited by JA (or methyl-JA) in both the absence and presence of auxin. Previously,
we have observed a correlation between elongation growth and cytosolic pH (pHi), in which auxin lowers pHi, and growth inhibitors such as ABA raise pHi. We examined the effect of low concentrations of methyl-JA on pHi with dual emission dye, carboxy seminaphthorhodafluor-1, and confocal microscopy. To confirm these studies, we also used
in vivo 31P NMR spectrometry to ascertain the changes in pHi after addition of jasmonate to maize coleoptiles. Coleoptiles grown in either the absence or presence of norflurazon responded
to methyl-JA or JA by increases in pHi of approximately 0.2 pH unit. This response occurs over a period of 15–20 min and appears to be independent of endogenous
ABA. This alkalization induced by JA is likely to form a permissive environment for JA signal transduction pathway(s).
Received February 5, 1999; accepted August 25, 1999 相似文献
10.
Ouoimare Arezki Philippe Boxus Claire Kevers Thomas Gaspar 《In vitro cellular & developmental biology. Plant》2000,36(5):398-401
Summary
Eucalyptus camaldulensis can be micropropagated through so-called meristematic agglomerates (MAs). MAs (4–6 mm diameter) are dense shoot clusters
initiated by the outgrowth of numerous successive buds. Their reddish nature is associated with an increase in their endogeneous
cytokinin level during the exponential phase of growth. A simultaneous decrease in the auxin level favors a high cytokinin/auxin
ratio. A low level of polyamines occurs at the time of the lowest level of auxins. Slow hormone release by activated charcoal
plays a role in this very prolific organogenesis. 相似文献
11.
L. H. Jones 《Journal of Plant Growth Regulation》1998,17(4):205-213
The metabolism of cytokinins in tissue cultures of two oil palm clones previously known to regenerate palms ultimately manifesting
normal and abnormal flowering was studied using radiolabeled benzyladenine and isopentenyladenosine, with particular regard
to the kinetics of formation of the cytokinin 9-glucoside. Labeled products were separated by high performance liquid chromatography
and identified by comparison of retention times with authentic cytokinin standards run immediately before or after the experimental
sample. Using benzyladenine, which is insensitive to cytokinin oxidase, ribotide appeared rapidly and then declined. 6-Benzylaminopurine
(BA) 9-glucoside quickly became the major soluble product with some formation of riboside. No other ethanol-soluble products
were found. Over an incubation period of 24 h up to 30% of label appeared in the ethanol-insoluble fraction. The uptake of
label was consistently faster in the normal than the abnormal clone. Dose-rate and time course experiments produced an in
vivo asymptotic dose-response curve for the accumulation of BA 9-glucoside analogous to a Michaelis-Menten first-order reaction
with a ~~``V
max' of 3.5 nmol·g−1·h−1 (on a fresh weight basis) and a ``K
m
' of 0.12 mm. There were no differences between clones in the rate of synthesis. Using isopentenyladenosine, which is susceptible to cytokinin
oxidase and cannot be glucosylated without prior deribosylation, a complex pattern of metabolism was seen, with much slower
production of 9-glucoside. A number of transient unidentified compounds were seen, together with adenosine and adenine. Comparison
of normal and abnormal flowering clones showed striking differences in the kinetics of production of a compound thought to
be [9R]Z and in a transient compound eluting at 22 min which accounted for 42% of the radioactivity after a 7-h incubation
in the abnormal line. By 17 h there was no difference between normal and abnormal lines in the radioactivity in this compound.
Cytokinin uptake was slower in the abnormal than in the normal flowering clone.
Received December 17, 1997; accepted August 24, 1998 相似文献
12.
Summary Growth characteristics of tobacco protoplasts containing rolA linked to its own promoter, or the rolB, or rolC genes of Agrobacterium rhizogenes linked to the Cauliflower Mosaic Virus 35S RNA promoter were compared with those from untransformed plants. RolA protoplasts require auxin and cytokinin for callus formation. Protoplasts overexpressing rolB and C form callus in the absence of exogenously applied auxin and cytokinin, respectively. Long term callus growth requires auxin, but the requirement for cytokinin is not critical. Optimal transient expression of an auxin responsive promoter element occurred at lower external levels of auxin in rolB and rolC protoplasts compared with untransformed protoplasts. Addition of putrescine was required for auxin responsive transient gene expression in rolA protoplasts suggesting that polyamines, or their products affect gene expression in rolA plants.Abbreviations T-DNA
transferred DNA
- TL-DNA
left transferred DNA
- NAA
naphthalene acetic acid
- PEG
polyethylene glycol
- GUS
glucuronidase
- CaMV
cauliflower mosaic virus 相似文献
13.
Plant Glutathione S-Transferases, a Tale of Theta and Tau 总被引:2,自引:0,他引:2
F. Droog 《Journal of Plant Growth Regulation》1997,16(2):95-107
14.
15.
Inoculation and nitrate alter phytohormone levels in soybean roots: differences between a supernodulating mutant and the wild type 总被引:9,自引:0,他引:9
The levels of different cytokinins, indole-3-acetic acid (IAA) and abscisic acid (ABA) in roots of Glycine max [L.] Merr. cv. Bragg and its supernodulating mutant nts382 were compared for the first time. Forty-eight hours after inoculation with Bradyrhizobium, quantitative and qualitative differences were found in the root's endogenous hormone status between cultivar Bragg and the
mutant nts382. The six quantified cytokinins, ranking similarly in each genotype, were present at higher concentrations (30–196% on average
for isopentenyl adenosine and dihydrozeatin riboside, respectively) in mutant roots. By contrast, the ABA content was 2-fold
higher in Bragg, while the basal levels of IAA [0.53 μmol (g DW)−1, on average] were similar in both genotypes. In 1 mM NO3
−-fed Bragg roots 48 h post-inoculation, IAA, ABA and the cytokinins isopentenyl adenine, and isopentenyl adenosine quantitatively
increased with respect to uninoculated controls. However, only the two cytokinins increased in the mutant. High NO3
− (8 mM) markedly reduced root auxin concentration, and neither genotypic differences nor the inoculation-induced increase
in auxin concentration in Bragg was observed under these conditions. Cytokinins and ABA, on the other hand, were little affected
by 8 mM NO3
−. Root IAA/cytokinin and ABA/cytokinin ratios were always higher in Bragg relative to the mutant, and responded to inoculation
(mainly in Bragg) and nitrate (both genotypes). The overall results are consistent with the auxin-burst-control hypothesis
for the explanation of autoregulation and supernodulation in soybean. However, they are still inconclusive with respect to
the inhibitory effect of NO3
−.
Received: 16 April 1999 / Accepted: 13 December 1999 相似文献
16.
Sulphate is a major macronutrient required for the synthesis of the sulphur (S)-containing amino acid cysteine and thus is
critical for cellular metabolism, growth and development and response to various abiotic and biotic stresses. A recent genome-wide
expression study suggested that several auxin-inducible genes were up-regulated by S deficiency in Arabidopsis. Here, we examined
the relationship between auxin signaling and S deficiency. Investigation of DR5::GUS expression patterns indicates that auxin accumulation and/or response is suppressed by S deficiency. Consistently, S deficiency
resulted in the suppression of lateral root development, but the axr1-3 mutant was insensitive to this response. Furthermore, the activation of the promoter for the putative thioglucosidase gene
(At2g44460) by S deficiency was suppressed by auxin, cytokinin and abscisic acid (ABA). Interestingly, the activation of At2g44460
by S deficiency is regulated by the availability of carbon and nitrogen nutrients in a tissue-specific manner. These results
demonstrate that auxin plays a negative role in signaling to S deficiency. Given that activation of the genes encoding the
sulphate transporter SULTR1;2 and 5′-adenylylsulphate reductase APR2 are suppressed by cytokinin only, we hypothesize that
while cytokinin may play an important role in general S deficiency response, auxin might be only involved in a subset of S
deficiency responses such as the release of thiol groups from the S storage sources.
Electronic Supplementary Material Supplementary material is available in the online version of this article at and is accessible for authorized users. 相似文献
17.
18.
V. Chalupa 《Biologia Plantarum》1989,31(5):400-407
Shoot multiplication of Larixdecidua was achieved using axillary and adventitious buds. The formation of axillary buds was stimulated on shoot tips soaked in
a cytokinin solution (BAP 10-50 mg 1−1 for 2–4 h. Adventitious buds were induced on cotyledons, needles and vegetative buds cultured on WPM or QL medium supplemented
with cytokinin (BAP 1–3 mg 1−1). The shoot formation from induced axillary and adventitious buds was promoted on WPM or QL medium containing a low concentration
of auxin (IBA 0.1 mg 1−1). Shoot multiplication of Pinussylvestris was stimulated on WPM, MS, and QL media supplemented with a low concentration of cytokinin (BAP 0.2 mg 1−1) and auxin (IBA 0.1 mg 1−1). Shoot segments produced 2–5 new axillary shoots within 4–5 weeks. Root initiation was stimulated on larch and pine shoots
cultured first on WPM supplemented with auxins (NAA and IBA) and later transferred to auxin-free medium. 相似文献
19.
20.
M. Foiani E. Nadjar-Boger R. Capone S. Sagee T. Hashimshoni Y. Kassir 《Molecular & general genetics : MGG》1996,253(3):278-288
In this report we study the regulation of premeiotic DNA synthesis in Saccharomyces cerevisiae. DNA replication was monitored by fluorescence-activated cell sorting analysis and by analyzing the pattern of expression
of the DNA polymerase α-primase complex. Wild-type cells and cells lacking one of the two principal regulators of meiosis,
Ime1 and Ime2, were compared. We show that premeiotic DNA synthesis does not occur in ime1Δ diploids, but does occur in ime2Δ diploids with an 8–9 h delay. At late meiotic times, ime2Δ diploids exhibit an additional round of DNA synthesis. Furthermore, we show that in wild-type cells the B-subunit of DNA
polymerase α is phosphorylated during premeiotic DNA synthesis, a phenomenon that has previously been reported for the mitotic
cell cycle. Moreover, the catalytic subunit and the B-subunit of DNA polymerase α are specifically degraded during spore formation.
Phosphorylation of the B-subunit does not occur in ime1Δ diploids, but does occur in ime2Δ diploids with an 8–9 h delay. In addition, we show that Ime2 is not absolutely required for commitment to meiotic recombination,
spindle formation and nuclear division, although it is required for spore formation.
Received: 20 February 1996 / Accepted: 7 June 1996 相似文献