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1.
The synthesis of DNA in nuclei and organellar nucleoids at the various stages of somatic embryogenesis in carrot (Daucus carota L. cv. Kurodagosun) was analyzed using anti-5-bromo-2′-deoxyuridine (BrdU) immunofluorescence microscopy. The active syntheses
of both nuclear and organellar DNA started in the cells forming the embryo proper 3 d after the initiation of embryogenesis,
but not in cells forming suspensor-like cell aggregates. In the early globular embryo, active DNA syntheses were continuously
observed in the whole embryo proper, except for the progenitor cells of the root apical meristem (RAM) and shoot apical meristem
(SAM). These were recognized as slowly cycling cells with a non-BrdU-labelled nucleus and strongly BrdU-labelled organellar
nucleoids. At the heart- and torpedo-shaped embryo stages, both nuclear and organellar DNA syntheses were inactive in the
presumptive RAM and SAM. Thus, slowing down of organellar DNA synthesis is not coupled with, but is later than, that of nuclear
DNA synthesis in the progenitor cells of the embryonic RAM and SAM. These findings clearly indicate that the timing of DNA
synthesis is similar in the progenitor cells of both the RAM and SAM in the early stages of somatic embryogenesis.
Received: 18 January 2000 / Accepted: 2 March 2000 相似文献
2.
Yamamoto N Kobayashi H Togashi T Mori Y Kikuchi K Kuriyama K Tokuji Y 《Journal of plant physiology》2005,162(1):2493-54
Using a direct somatic embryogenesis system in carrot, we examined the role of DNA methylation in the change of cellular differentiation state, from somatic to embryogenic. 5-Azacytidine (aza-C), an inhibitor of DNA methylation suppressed the formation of embryogenic cell clumps from epidermal carrot cells. Aza-C also downregulated the expression of DcLEC1c, a LEC1-like embryonic gene in carrot, during morphogenesis of embryos. A carrot DNA methyltransferase gene, Met1-5 was expressed transiently after the induction of somatic embryogenesis by 2,4-dichlorophenoxyacetic acid (2,4-D), before the formation of embryogenic cell clumps. These findings suggested the significance of DNA methylation in acquiring the embryogenic competence in somatic cells in carrot. 相似文献
3.
Abscisic acid and stress treatment are essential for the acquisition of embryogenic competence by carrot somatic cells 总被引:5,自引:0,他引:5
Studies of carrot embryogenesis have suggested that abscisic acid (ABA) is involved in somatic embryogenesis. A relationship between endogenous ABA and the induction of somatic embryogenesis was demonstrated using stress-induced system of somatic embryos. The embryonic-specific genes C-ABI3 and embryogenic cell proteins (ECPs) were expressed during stress treatment prior to the formation of somatic embryos. The stress-induction system for embryogenesis was clearly distinguished by two phases: the acquisition of embryogenic competence and the formation of a somatic embryo. Somatic embryo formation was inhibited by the application of fluridone (especially at 10−4 M), a potent inhibitor of ABA biosynthesis, during stress treatment. The inhibitory effect of fluridone was nullified by the simultaneous application of fluridone and ABA. The level of endogenous ABA increased transiently during stress. However, somatic embryogenesis was not significantly induced by the application of only ABA to the endogenous level, in the absence of stress. These results suggest that the induction of somatic embryogenesis, in particular the acquisition of embryogenic competence, is caused not only by the presence of ABA but also by physiological responses that are directly controlled by stresses. 相似文献
4.
Somatic embryogenesis in soybean via somatic embryo cycling 总被引:4,自引:0,他引:4
Wennuan Liu Patricia J. Moore Glenn B. Collins 《In vitro cellular & developmental biology. Plant》1992,28(3):153-160
Summary The objectives of the present research were: a) to develop an efficient soybean embryogenic regeneration system characterized
by a high frequency of explant response and a large number of somatic embryos per explant; b) to evaluate the factors affecting
somatic embryogenesis via somatic embryo cycling; and c) to identify the origin of somatic embryos in the system. A highly
improved and efficient system for soybean somatic embryogenesis was established using somatic embryo cotyledons and somatic
embryo hypocotyl/radicle explants plated on α-naphthaleneacetic acid (NAA) or 2,4-dichlorophenoxyacetic acid (2,4-D) supplemented
MS basal media. The system included somatic embryo cycling between liquid and solid medium and it consistently gave rise to
a much higher frequency of explant response and a larger number of embryos per responding explant than those obtained from
zygotic cotyledon explant tissues. Genotype, differences were observed for response in some of the treatments with cv “Fayette”
being more responsive than “J103”. Histological studies revealed that somatic embryos induced in the somatic embryo cycling
system originated almost exclusively from epidermal cells on both 2,4-D and NAA inductive media. The cells of the epidermis
proliferated to produce somatic embryos directly without an intervening callus phase. A single-cell origin of somatic embryos
was observed in cultures on a 40 mg/liter 2,4-D treatment. A large number of responding cells in the epidermis was also observed
in the 10 mg/liter NAA treatment. The single-cell origin of somatic embryos from epidermal layers of the explant tissues should
facilitate development of an efficient transformation system for soybean. 相似文献
5.
M. Griga 《Biologia Plantarum》2002,45(2):173-182
The morphological and anatomical aspects of direct and indirect somatic embryogenesis in pea were described. Direct embryos were induced from shoot apical meristems of 3 to 5-d-old pea seedlings, embryogenic callus originated from immature pea zygotic embryos or shoot apices. Auxin (picloram, 2,4-dichlorophenoxyacetic acid) was necessary to induce somatic embryos. The developmental stages typical for pea zygotic embryos were detected. Globular and heartshaped somatic embryos were morphologically similar to their zygotic counterparts; in contrast, torpedo and cotyledonary somatic embryos displayed great morphological variation, which affected mainly cotyledons (size, shape, number). Based on anatomical sections, possible ways of somatic embryo formation and localization of initiation sites within primary explant tissue have been proposed. The multicellular origin of somatic embryos is supposed in both systems of pea somatic embryogenesis under investigation. 相似文献
6.
Regeneration of Acacia mangium through somatic embryogenesis 总被引:2,自引:0,他引:2
Somatic embryogenesis and whole plant regeneration were achieved in callus cultures derived from immature zygotic embryos
of Acacia mangium. Embryogenic callus was induced on MS medium containing combinations of TDZ (1–2 mg/l), IAA (0.25–2 mg/l) and a mixture of
amino acids. Globular embryos developed on embryogenic callus cultured on the induction medium. Nearly 42% of embryogenic
cultures with globular embryos produced torpedo- and cotyledonary-stage embryos by a two-step maturation phase. The first
stage occurred on 1/2-strength MS basal medium containing 30 g/l sucrose and 5 mg/l GA3 followed by the second stage on 1/2-strength MS basal medium containing 50 g/l sucrose. Of the cotyledonary-stage somatic
embryos, 11% germinated into seedlings that could be successfully transferred to pots. Light- and scanning electron microscopy
showed that the somatic embryos originated from single cells of the embryogenic callus. Further, a single cell layer could
be detected beneath the developing somatic embryos that appeared to be a demarcation layer isolating the somatic proembryonic
structure from the rest of the maternal callus. A suspensor-like structure connected the globular embryos to the demarcation
layer. This is the first successful report of plant regeneration through somatic embryogenesis for this economically important
tropical forest species.
Received: 20 January 2000 / Revision received: 28 September 2000 / Accepted: 29 September 相似文献
7.
High-frequency plant regeneration through cyclic secondary somatic embryogenesis in black pepper (Piper nigrum L.) 总被引:5,自引:0,他引:5
A high-frequency plantlet regeneration protocol was developed for black pepper (Piper nigrum L.) through cyclic secondary somatic embryogenesis. Secondary embryos formed from the radicular end of the primary somatic embryos which were originally derived from micropylar tissues of germinating seeds on growth regulator-free SH medium in the absence of light. The process of secondary embryogenesis continued in a cyclic manner from the root pole of newly formed embryos resulting in clumps of somatic embryos. Strength of the medium and sucrose concentration influenced the process of secondary embryogenesis and fresh weight of somatic embryo clumps. Full-strength SH medium supplemented with 1.5% sucrose produced significantly higher fresh weight and numbers of secondary somatic embryos while 3.0 and 4.5% sucrose in the medium favored further development of proliferated embryos into plantlets. Ontogeny of secondary embryos was established by histological analysis. Secondary embryogenic potential was influenced by the developmental stage of the explanted somatic embryo and stages up to “torpedo” were more suitable. A single-flask system was standardized for proliferation, maturation, germination and conversion of secondary somatic embryos in suspension cultures. The system of cyclic secondary somatic embryogenesis in black pepper described here represents a permanent source of embryogenic material that can be used for genetic manipulations of this crop species. 相似文献
8.
Lambé Pascal Mutambel Hity S.N. Deltour Roger Dinant Monique 《Plant Cell, Tissue and Organ Culture》1998,55(1):23-29
Three genotypes of Pearl millet were screened in vitro for induction of embryogenic callus, somatic embryogenesis and regeneration.
Shoot apices excised from in vitro germinated seedlings or immature embryos isolated from green house established plants were
used as primary explants. The frequency of embryogenic callus initiation was significantly higher in shoot apices in comparison
with immature zygotic embryos. Moreover, differences between genotypes were minimal when using shoot apices. Friable embryogenic
calli (type II) developed on the initial nodular calli after 1 to 3 months of culture. The frequency of type II callus is
related to the composition of the maintenance medium and they were more often found in ageing cultures. The transfer of embryogenic
calli onto auxin-free medium was sufficient for inducing somatic embryo development in short-term culture (3 months) while
a progressive loss in regeneration potential was observed with increasing time of subcultures. Maturation of embryogenic calli
on medium supplemented with activated charcoal, followed by germination of somatic embryos on medium supplemented with gibberellic
acid, restored regeneration in long-term cultures.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
9.
Somatic embryogenesis from pea embryos and shoot apices 总被引:3,自引:0,他引:3
Conditions were defined for plant regeneration via somatic embryogenesis in pea, using explants from immature zygotic embryos or from shoot apices. For the induction of somatic embryos, an auxin (picloram or 2,4-dichlorophenoxyacetic acid) was required. Embryogenic callus originated from embryonic axis tissue of immature embryos and from the axillary-bud region and the plumula of shoot apices. A clear effect of embryo size on somatic embryogenesis was shown. There were differences in frequency of somatic embryogenesis among the five genotypes used in the study. Additions of BA to auxin-containing medium reduced embryo production. Histological examinations confirmed the embryogenic nature of the immature embryo cultures and revealed that somatic embryos originated from the meristematic areas near the callus surface.Abbreviations BA
benzyladenine
- 2,4-D
2,4-dichlorophenoxyacetic acid
- NAA
naphthaleneacetic acid
- picloram
4-amino-3,5,6-trichloropicolinic acid 相似文献
10.
Hajime Shiota Sukmin Ko Shinko Wada Claudia Tomiko Otsu Ichiro Tanaka Hiroshi Kamada 《Plant Physiology and Biochemistry》2008,46(5-6):550-558
Carrot (Daucus carota) somatic embryogenesis has been extensively used as an experimental system for studying embryogenesis. In maturing zygotic embryos, abscisic acid (ABA) is involved in acquisition of desiccation tolerance and dormancy. On the other hand, somatic embryos contain low levels of endogenous ABA and show desiccation intolerance and lack dormancy, but tolerance and dormancy can be induced by exogenous application of ABA. In ABA-treated carrot embryos, some ABA-inducible genes are expressed. We isolated the Daucus carota bZIP1 (DcBZ1) gene encoding a G-box binding factor-type basic region/leucine zipper (GBF-type bZIP) factor from carrot somatic embryos. The expression of DcBZ1 was detected in embryogenic cells, non-embryogenic cells, somatic embryos, developing seeds, seedlings, and true leaves. Notably, higher expression was detected in embryogenic cells, true leaves, and seedlings. The expression of DcBZ1 increased in seedlings and true leaves after ABA treatment, whereas expression was not affected by differences in light conditions. During the development of zygotic and somatic embryos, increased expression of DcBZ1 was commonly detected in the later phase of development. The recombinant DcBZ1 protein showed specific binding activity to the two ABA-responsive element-like motifs (motif X and motif Y) in the promoter region of the carrot ABA-inducible gene according to results from an electrophoretic mobility shift assay. Our findings suggest that the carrot GBF-type bZIP factor, DcBZ1, is involved in ABA signal transduction in embryogenesis and other vegetative tissues. 相似文献
11.
Direct somatic embryogenesis was induced in root tissues of the Cichorium hybrid `474' (C. intybus L. var. sativum×C. endivia L. var. latifolia). Addition of β-d-glucosyl Yariv reagent (βGlcY), a synthetic phenylglycoside that specifically binds arabinogalactan-proteins (AGPs), to the
culture medium blocked somatic embryogenesis in a concentration-dependent manner with complete inhibition of induction occurring
at 250 μM βGlcY. The AGP-unreactive α-d-galactosyl Yariv reagent had no biological activity in this system. Upon transfer of 250 μM βGlcY-treated roots to control
conditions, somatic embryogenesis was recovered with a time course similar to that of control roots. The βGlcY penetrated
roots and bound abundantly to developing somatic embryos, to the root epidermis and the stele. Immunofluorescence and immunogold
labelling using monoclonal antibodies (JIM13, JIM16 and LM2) revealed that AGPs were localised in the outer cell walls peripheral
cells of the globular embryo. A spatio-temporal expression of AGPs appeared to be associated with differentiation events in
the somatic embryo during the transition from the globular stage to the torpedo stage. To verify βGlcY specificity, molecules
that bound βGlcY were extracted from treated conditioned medium and identified as AGPs by using the same monoclonal antibodies.
In addition, AGPs were found to be abundantly present in the medium during embryogenic culture. All of these results establish
the implication of AGPs in embryo development, and their putative role in somatic embryogenesis is discussed.
Received: 26 August 1999 / Accepted: 28 January 2000 相似文献
12.
Somatic embryogenesis in carrot can be induced by the treatment of shoot apices with various kinds of stress chemicals. Using
this system, we previously identified a phosphoprotein (ECPP-44) that appears to be involved in the induction of somatic embryogenesis.
We have also isolated and characterized a cDNA encoding ECPP-44. In this study, to further characterize ECPP-44, we performed
Western blot and immuno-precipitation analyses. Western blot analysis revealed that ECPP-44 was present in embryogenic cells,
stress- and non-stress-treated tissues, and somatic embryos but was absent in non-embryogenic cells. Furthermore, ECPP-44
was found in some parts of the carrot plant, such as tap roots, leaves, and flowers (18–26 days after fertilization) but not
in mature dry seeds. Interestingly, we could detect phosphorylated ECPP-44 in embryogenic cells and somatic embryos but not
in non-embryogenic cells, tap roots, and non-stress-treated shoot apices by immunoprecipitation analysis, even though the
protein existed. Our results suggest that ECPP-44 may perform some role in the induction or maintenance of embryogenic competence. 相似文献
13.
Lydia Reidiboym-Talleux Florence Diemer Martine Sourdioux Kathy Chapelain Ghislaine Grenier-De March 《Plant Cell, Tissue and Organ Culture》1998,55(3):199-209
Three different types of morphogenesis were identified in embryogenic cultures of Prunus avium grown on a proliferation medium
containing 0.54 μM NAA, 0.46 μM kinetin and 0.44 μM BA: a friable hyperhydric callus, repetitive embryogenesis and an embryogenic
tissue. Translucent and white somatic embryos were produced from the three types of morphogenesis but mainly from the embryogenic
tissue. These somatic embryos showed histological and cytological teratological features such as highly differentiated cells
with shrunken cytoplasm and destructured nuclei. For the four lines studied, somatic embryo production was improved by transferring
the embryogenic tissue to developmental media without auxin and cytokinin but supplemented with maltose alone or maltose and
10 μM ABA. Three weeks after transfer, the line showing the most embryogenesis produced 1404 somatic embryos per gram of embryogenic
tissue. A concentration of 263 mM maltose significantly increased the number of white somatic embryos for L 10 line, while
translucent somatic embryo production was improved by 88 mM maltose for L 16 line. The combination of maltose and ABA produced
different effects with each line. When used with 88 mM maltose, 10 μM ABA significantly increased white somatic embryo production
for two lines but decreased the production for one line. When combined with 263 mM maltose, ABA had no effect on white somatic
embryo production but significantly decreased the number of translucent somatic embryos. Cells of white somatic embryos contained
protein storage reserves and numerous lipid bodies, while those of translucent embryos did not contain storage reserves or
lipid bodies. After a two-month cold treatment conversion rate of white and translucent somatic embryos reached 8.5% and 35.2%
respectively.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
14.
15.
The arabinogalactan protein-binding β-d-glucosyl Yariv reagent (βGlcY) was applied to the various developmental stages of embryogenic carrot (Daucus carota L. cv. Early Nantes) cell-suspension cultures. Roots without shoot structures were produced in cultures grown under embryo-inducing
conditions in medium containing βGlcY. Only low concentrations of βGlcY permitted the subsequent production of embryos in
these cultures. When early stage embryos were transferred to medium containing βGlcY, the roots elongated greatly while the
shoot apices expanded radially. These embryos did not progress to the next developmental stage. Torpedo embryos and plantlets,
however, showed an overall inhibition of growth in the presence of βGlcY. Developmental stage therefore appears to determine
how cultures and embryos respond to βGlcY, root growth being promoted in the early stages, and overall growth reduced in the
late stages.
Received: 1 July 1997 / Accepted: 31 July 1997 相似文献
16.
High-frequency plant regeneration via somatic embryogenesis and organogenesis and in vitro flowering of regenerated plantlets in Panax ginseng 总被引:4,自引:0,他引:4
W. Tang 《Plant cell reports》2000,19(7):727-732
The morphogenesis ability of light yellowish globular callus derived from cotyledons of mature zygotic embryos of Panax ginseng was investigated. The optimal media for somatic embryogenesis and shoot organogenesis were MS medium containing 0.5 mg l–1 2,4-dichlorophenoxyacetic acid, 0.1 mg l–1 6-benzyladenine (BA), and 500 mg l–1 lactoalbumin hydrolysate, and SH medium supplemented with 0.5 mg l–1 α-naphthaleneacetic acid, 0.1 mg l–1 BA, and 500 mg l–1casein hydrolysate. The influences of glucose, mannose, fructose, and sorbose in the media on somatic embryogenesis and shoot
organogenesis were revealed as differences in the numbers of somatic embryos and adventitious shoots per gram of morphogenic
callus. The best regeneration of somatic embryos was obtained on medium containing glucose, with a mean of 8.7 somatic embryos
per gram of callus. The best regeneration of shoots was observed on medium containing fructose, with an average of 12.2 adventitious
shoots per gram of callus. Of the somatic embryos 95% were converted into regenerated plantlets, and 100% of adventitious
shoots rooted to form regenerated plantlets. Regenerated plants were successfully established in soil. Flowering was observed
in 5.7% of the regenerated plants derived from shoot organogenesis and in 1.4% of the regenerated plants derived from somatic
embryogenesis.
Received: 1 December 1998 / Revision received: 13 September 1999 / Accepted: 20 September 1999 相似文献
17.
A simple method to induce somatic embryogenesis from seeds of rapid-cycling Brassica napus is described. Seedlings cultured on Murashige and Skoog (MS) basal medium produced somatic embryos directly on hypocotyls
and cotyledons after 2 to 3 subcultures onto the same medium. A low pH of the medium (3.5–5) was more conducive to somatic
embryogenesis than a higher pH (6 and 7). Embryogenic potential of the seeds was inversely correlated to seed age: about 41–68%
of immature seeds between the ages of 14 and 28 days after pollination (DAP) formed somatic embryos compared to 0–11% of the
seeds obtained 29–37 DAP. About 54% of the somatic embryos produced secondary embryos after subculturing onto the same medium.
The embryogenic potential of the cultures has been maintained on MS basal medium for 2 years (12 generations) without diminution.
Up to 75% of the secondary embryos developed into plantlets on MS medium enriched with 10–6
M zeatin, and 40% of these produced flowers when transferred to an optimised flower-induction medium. Viable seeds were produced
in self-pollinated in vitro flowers.
Received: 15 February 2000 / Revision received: 18 July 2000 / Accepted: 19 July 2000 相似文献
18.
The development of a rapid protocol for high-efficiency somatic embryogenesis and plant regeneration from seed-derived embryogenic
callus cultures of California poppy (Eschscholzia californica Cham.) is reported. The optimized procedure required less than 13 weeks from the initiation of seed cultures to the recovery
of plantlets and involved the sequential transfer of cultures onto solid Murashige and Skoog basal medium containing three
different combinations of growth regulators. All steps were performed at 25 °C. Friable primary callus was induced from seeds
of E. californica cultured on medium supplemented with 1.0 mg l−1 2,4-dichlorophenoxyacetic acid. The primary callus was transferred to medium containing 1.0 mg l−1 1-naphthaleneacetic acid and 0.5 mg l−1 6-benzylaminopurine to establish embryogenic callus and promote somatic embryogenesis. Regenerated plantlets were recovered
after the conversion of somatic embryos on medium containing 0.05 mg l−1 6-benzylaminopurine and showed normal development. Embryogenic callus was induced at a frequency of 85%, an average of 45
somatic embryos were produced per callus, 90% of the somatic embryos converted, and about 70% of the plantlets were recovered
in soil. The growth rate of somatic embryo-derived shoots could be increased by gibberellic acid treatment, but the resulting
plantlets were hyperhydritic.
Received: 14 February 1999 / Revision received: 27 April 1999 / Accepted: 14 May 1999 相似文献
19.
Possible involvement of abscisic acid in the induction of secondary somatic embryogenesis on seed-coat-derived carrot somatic embryos 总被引:1,自引:0,他引:1
When seed coats (pericarps) were picked from 14-day-old carrot (Daucus carota) seedlings and cultured on agar plates, embryogenic cell clusters were produced very rapidly at a high frequency on the open side edge. Embryo induction progressed without auxin treatment; indeed treatment caused the formation of non-embryogenic callus. The embryogenic tissues (primary embryos) developed normally until the torpedo stage; however, after this a number of secondary somatic embryos were produced in the hypocotyl and root regions. Tertiary embryos were formed on some of the secondary embryos, but many developed into normal plantlets. The primary embryos contained significantly higher levels of abscisic acid (ABA) than the hypocotyl-derived normal and seed-coat-derived secondary embryos. Fluridone inhibited the induction of secondary embryogenesis, while exogenously supplied ABA induced not only tertiary embryogenesis on the seed-coat-derived secondary embryos, but also secondary embryos on the hypocotyl-derived normal somatic embryos. These results indicate that ABA is one of the important endogenous factors for the induction of secondary embryogenesis on carrot somatic embryos. Higher levels of indole-3-acetic acid (IAA) in primary embryos also suggest the presence of some concerted effect of ABA and IAA on the induction of secondary embryogenesis in primary embryos. 相似文献
20.
In vitro somatic embryogenesis was achieved from zygotic embryo explants of a woody angiosperm species, the spindle tree,
cultivated on various culture media differing in their sugar type and concentration, or in the applied osmotic potential.
The highest frequency of somatic embryogenesis was obtained with a 350 mM sucrose, or a 89 mM glucose concentration in the
culture medium. Experiments with culture media differing only in osmotic potential indicated that a minimal threshold osmotic
potential is required to stimulate the emergence of somatic embryos. Elevated concentrations of glucose have an inhibitory
effect, independent of their osmotic effect, while elevated concentrations of sucrose mainly act osmotically, stimulating
the emergence of numerous somatic embryos.
Received: 15 July 1997 / Revision received: 27 October 1997 / Accepted: 24 March 1998 相似文献