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1.
Iris R. von Recklinghausen Anna Iwanowska Henk Kieft Andreas P. Mordhorst Jan H. N. Schel André A. M. van Lammeren 《Protoplasma》2000,211(3-4):217-224
Summary Seeds of theArabidopsis thaliana mutant primordia timing (pt) were germinated in 2,4-dichlorophenoxyacetic acidcontaining liquid medium. The seedlings formed somatic embryos and nonembryogenic and embryogenic callus in vitro in a time period of approximately two to three weeks. Embryogenesis and callus formation were monitored with respect to origin, structure, and development. Ten days after germination globular structures appeared in close vicinity of and on the shoot apical meristem (SAM). Somatic embryos formed either directly on the SAM region of the seedling or indirectly on embryogenic callus that developed at the SAM zone. Globular structures developed along the vascular tissue of the cotyledons as well, but only incidentally they formed embryos. Upon deterioration, the cotyledons formed callus. Regular subculture of the embryogenic callus gave rise to high numbers of somatic embryos. Such primary somatic embryos, grown on callus, originated from meristematic cell clusters located under the surface of the callus. Embryos at the globular and heart-shape stage were mostly hidden within the callus. Embryos at torpedo stage appeared at the surface of the callus because their axis elongated. Secondary somatic embryos frequently formed directly on primary ones. They preferentially emerged from the SAM region of the primary somatic embryos, from the edge of the cotyledons, and from the hypocotyl. We conclude that the strong regeneration capacity of thept mutant is based on both recurrent and indirect embryogenesis.Abbreviations 2,4-D
2,4-dichlorophenoxyacetic acid
- DIC
days in culture
- SAM
shoot apical meristem 相似文献
2.
An embryogenic suspension culture of Zea mays, genotype 4C1, was obtained from friable callus that was cultured on solid medium and had been obtained from zygotic embryos. The suspension contained non-dividing elongated cells, clusters of dividing isodiametric cells, and globular, ovoid, and polar stages of somatic embryos. The single somatic embryos were blocked in shoot meristem formation: when transferred to regeneration medium they developed a root and, at the shoot side, a green cap with meristematic cells, but a scutellum and leaf primordia were not formed. In medium containing 2,4-dichlorophenoxy acetic acid, somatic embryos formed embryogenic callus aggregates, consisting of globular stage somatic embryos attached to each other via undifferentiated callus cells. These somatic embryos developed into mature embryos with the zygotic histological characteristics, such as scutellum and leaf primordia, in maturation medium, and then regenerated into plants in regeneration medium. By omitting the maturation phase, regeneration occurred via organogenesis. Polyembryos, i. e. embryos attached to each other without callus tissue in between, behaved as single somatic embryos. It is concluded that the attached callus tissue provides a factor that stimulates scutellum and leaf primordia formation.Abbreviations CMM
callus maintenance medium
- 2,4D
2,4-dichlorophenoxy acetic acid
- PCV
packed cell volume
- MS
Murashige and Skoog medium 相似文献
3.
Summary This study compares the development of shoot apical meristems of white spruce somatic and zygotic embryos during germination.
In mature somatic embryos, the functional part of the shoot apical meristem was bi-layered. After partial drying, a normal
shoot meristem was formed from these two cell layers during germination. Other cells within the meristem were vacuolated and
separated by intercellular air spaces. In the absence of the partial drying treatment, somatic embryos enlarged in size primarily
due to vacuolation of cells and the formation of large intercellular air spaces. A majority of these somatic embryos failed
to form a functional shoot apical meristem. Compared with somatic embryos, the shoot apical meristem of a mature zygotic embryo
was well organized with a densely cytoplasmic apical layer. The cells within the meristem were tightly packed. Judging from
the cell profiles during germination, all cells within the meristem of the zygotic embryo took part in the formation of the
vegetative shoot apical meristem. 相似文献
4.
Somatic embryos developed directly from 96 and 110 day post-anthesis Cercis canadensis L. (redbud) zygotic embryos from one of two trees sampled that were explanted onto modified Schenk and Hildebrandt medium amended with either 1, 2, 3 or 5 mg/1 2,4-D in combination with either 7.6 or 12. 6 mM ammonium ion. Although somatic embryogenesis was expressed on most media, the number of explants that produced somatic embryos and the mean number of embryos formed per explant were greatest on media that contained either 2 or 3 mg/1 2,4-D; 12.6 mM ammonium ion inhibited embryogenesis from 96 day post-anthesis explants. Zygotic embryos explanted 117 days after anthesis produced only callus and roots. Somatic embryos that were bottle-shaped or had distinct cotyledons organized roots on germination media, but only one embryo formed a shoot. No additional development occurred. Histological examination of somatic embryos showed that shoot apical meristems were poorly developed.Abbreviations 2,4-D
2, 4-dichlorophenoxyacetic acid
- NAA
1-naphthaleneacetic acid
- BAP
6-benzylaminopurine
- FPA
Formalin-propionic acid-ethanol (50%) 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.
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
7.
Summary In order to establish a protocol for somatic embryogenesis of annatto, Bixa orellana L., seeds (70 d after anthesis) from field-grown orchards had their coats dissected off, and immature zygotic embryos were
excised aseptically from immature seeds collected from field-grown trees and used as explants. Embryos were cultured onto
MS medium supplemented with or without different combinations of plant growth regulators and activated charcoal. Direct somatic
embryogenesis was induced on explants incubated either in Murashige and Skoog (MS), 2,4-dichlorophenoxyacetic acid (2,4-D),
and/or kinetin-supplemented media after 25 d of culture. The highest frequencies of embryogenesis and embryos per explant
were obtained on medium containing 2.26 μM 2.4-D, 4.52μM kinetin, and 1.0 gl−1 activated charcoal. The presence of charcoal was critical in increasing embryos per explant, to reduce the time to obtain
somatic embryos, and mainly to prevent callus proliferation and subsequent indirect somatic embryogenesis. No embryogenic
response was achieved when mature embryos were used. It was also observed that embryogenic response was significantly affected
by genotype. Histological investigations revealed that primary direct somatic embryos differentiated exclusively from the
protodermis or together with the outer ground meristem cell layers of the zygotic embryo axis, and from the protodermis of
zygotic cotyledons. Diverse morphological differences, including malformed embryos, were observed among somatic embryos. In
spite of the high frequencies of histodifferentiation of all embryo stages, a very low conversion frequency to normal plants
from somatic embryos was observed. 相似文献
8.
K. Suhasini A. P. Sagare K. V. Krishnamurthy 《In vitro cellular & developmental biology. Plant》1996,32(1):6-10
Summary Somatic embryos which originated from mature embryo axes of the chickpea (Cicer arietinum L.) showed varied morphologies. Embryos were classified based on shape of the embryo and number of cotyledons. “Normal” (zygotic-like)
embryos were bipolar structures with two cotyledons and a well-developed shoot and root apical meristem, whereas “aberrant”
embryos were horn-shaped, had single and multiple cotyledons, and were fasciated. Histological examination revealed the absence
of a shoot apical meristem in horn-shaped embryos. Fasciated embryos showed diaxial fusion of two embryos. Secondary embryogenesis
was also observed, in which the embryos emerged from the hypocotyl and cotyledonary region of the primary somatic embryo.
This report documents the absence of an apical meristem as a vital factor in the lack of conversion of aberrant somatic embryos. 相似文献
9.
The sequence of events in the functional body pattern formation during the somatic embryo development in cowpea suspensions is described under three heads. Early stages of somatic embryogenesis were characterized by both periclinal and anticlinal cell divisions. Differentiation of the protoderm cell layer by periclinal divisions marked the commencement of somatic embryogenesis. The most critical events appear to be the formation of apical meristems, establishment of apical-basal patterns of symmetry, and cellular organization in oblong-stage somatic embryo for the transition to torpedo and cotyledonary-stage somatic embryos. Two different stages of mature embryos showing distinct morphology, classified based on the number of cotyledons and their ability to convert into plantlets, were visualized. Repeated mitotic divisions of the sub-epidermal cell layers marked the induction of proembryogenic mass (PEM) in the embryogenic calli. The first division plane was periclinally-oriented, the second anticlinally-oriented, and the subsequent division planes appeared in any direction, leading to clusters of proembryogenic clumps. Differentiation of the protoderm layer marks the beginning of the structural differentiation in globular stage. Incipient procambium formation is the first sign of somatic embryo transition. Axial elongation of inner isodiametric cells of the globular somatic embryo followed by the change in the growth axis of the procambium is an important event in oblong-stage somatic embryo. Vacuolation in the ground meristem of torpedo-stage embryo begins the process of histodifferentiation. Three major embryonic tissue systems; shoot apical meristem, root apical meristem, and the differentiation of procambial strands, are visible in torpedo-stage somatic embryo. Monocotyledonary-stage somatic embryo induced both the shoot apical meristem and two leaf primordia compared to the ansiocotyledonary somatic embryo. 相似文献
10.
Somatic embryogenesis was obtained from cotyledon and mature zygotic embryo callus cultures of Terminalia chebula Retz. Callus cultures of cotyledon and mature zygotic embryo were initiated on induction medium containing Murashige and Skoog (MS) nutrients with 1.0 mg/l 2,4-dichlorophenoxyacetic acid (2,4-D) either 0.01 or 0.1 mg/l Kinetin and 30 g/l sucrose. Induction of somatic embryogenesis, proliferation and development was obtained through different culture passages. Embryogenic cotyledon callus with globular somatic embryos was obtained on MS basal medium supplemented with 50 g/l sucrose. Globular somatic embryos were observed from mature zygotic embryo callus on induction medium. Different stages of somatic embryo development from cotyledon and mature zygotic embryo calluses were observed on MS basal medium supplemented with 50 g/l sucrose after 4 weeks of culture. Histological studies have revealed the developmental stages of somatic embryos. A maximum of 40.3±1.45 cotyledonary somatic embryos/callus was obtained from mature zygotic embryo compared to 7.70±0.37 cotyledonary somatic embryos/callus initiated from cotyledons. Germination of somatic embryos and conversion to plants were achieved. Highest frequency of germination (46.66±0.88) of somatic embryos was obtained on MS basal medium containing benzyladenine (0.5 mg/l) with 30 g/l sucrose. 相似文献
11.
We elucidated the relationship between cell proliferation and somatic embryogenesis in the culture of carrot cotyledons. Fresh
weights of the cotyledon expiants were determined every five days while being cultured on a medium containing 2,4-D. Callus
production increased exponentially from Day 20 to Day 25, showing a two-fold rate of proliferation. To examine the embryogenic
potential of the callus, we pre-cultured cotyledon explants on an MS medium with 2,4-D, then transferred them to an MS basal
medium at five-day intervals. Somatic embryos formed most frequently when the cotyledons were pre-cultured for 20 days on
an MS medium that contained 5 μ2,4-D. The frequency of somatic embryo formation was 81%, while that of normal embryos with
two cotyledons was 51% among those formed on a hormone-free medium. We used FACScan analysis to relate the embryogenic potential
of the callus to the S phase in the cell cycle of cultured cells. The S phase was high after 25 days of culture on the medium
with 5 μM 2,4-D. In contrast, the frequency of normal embryogenesis was higher at Day 20 of the pre-culture period. Culturing
embryogenic calli on a medium with 5 μM 2,4-D was most favorable for producing somatic embryos with two cotyledons. We verified
that active somatic embryogenesis was apparently related to cell division activity; somatic embryos induced from actively
dividing cells were apt to accompany cotyledonary abnormality. 相似文献
12.
Immature and mature zygotic embryos of Paspalum scrobiculatum L. cv. PSC 1 cultured on MS or N6 nutrient medium supplemented with different concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D), formed embryogenic callus. Induction of embryogenic callus and subsequent somatic embryogenesis was possible at a lower concentration of 2,4-D on N6 than MS medium. Immature embryos were highly totipotent, forming somatic embryos at a higher frequency than mature embryos. Addition of amino acids (L-proline or L-tryptophan) to 2,4-D medium resulted in significant enhancement of embryogenesis on culture of mature embryos. Silver nitrate also supported an increased frequency of embryogenesis. Thus it is possible to have high frequency of somatic embryogenesis on culture of mature embryos, which are available in abundance and with ease than immature embryos. The somatic embryos readily germinated and formed plantlets on hormone-free regeneration medium. The regenerated plantlets were successful on transfer to soil and set seed. 相似文献
13.
Y. J. Kim M. K. Kim J. S. Shim R. K. Pulla D. C. Yang 《Russian Journal of Plant Physiology》2010,57(2):283-289
Somatic embryogenesis from single cells is important for normal plant regeneration of ginseng. Cotyledon explants from zygotic
embryos of two new ginseng cultivars, Chun-Poong and Yun-Poong, produced somatic embryos on Murashige and Skoog (MS) basal
medium and MS medium containing growth regulators. The highest frequency of single somatic embryo formation was obtained when
cotyledon explants were excised from premature (cultured for 1 day) zygotic embryos (about 6 mm in length) of both cvs. Chun-Poong
and Yun-Poong and then cultured on MS medium supplemented with 7% sucrose. The frequency of single somatic embryo formation
was strongly enhanced when Chun-Poong cotyledons were subjected to plasmolysis with 0.1–0.5 M sucrose for 24 h and Yun-Poong
cotyledons to plasmolysis with 1.0 M sucrose for 24 h and then cultured on MS medium with 2,4-D. 相似文献
14.
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
15.
Somatic embryos and embryogenic callus were initiated from immature zygotic embryos of ginseng (Panax ginseng C.A. Meyer). These somatic embryos were multiplied by adventitious (secondary and tertiary) embryogenesis and their growth and development were dependent on growth hormones in the medium. Auxins, 2,4-d, NAA, and IAA at 1.0 mg l-1 were effective in inducing secondary and tertiary somatic embryos, which proliferated directly from the apical or cotyledonary portions of the primary somatic embryos. Single somatic embryos or clusters or embryos developed from the explanted primary embryos. Cytokinin (Kn, BA) inhibited adventitious embryogenesis. Secondary somatic embryos developed to maturation and later regenerated into plantlets in two stage process; firstly elongation of the shoot axes on MS +1.0 mg l-1 Kn, secondly formation of root on 1.0 mg l-1 Kn+1.0 mg-1 GA3 medium.Abbreviations 2,4-d
2,4-dichlorophenoxyacetic acid
- NAA
naphthaleneacetic acid
- IAA
in-doleacetic acid
- Kn
kinetin
- BA
benzylaminopurine
- PSE
primary somatic embryo
- SSE
secondary somatic embryo
- TSE
tertiary somatic embryo 相似文献
16.
Mature zygotic embryos of Paspalum scrobiculatum L. cv. PSC 1 on MS or N6 nutrient medium supplemented with various concentrations of 2,4-D (4.5 – 22.5 μM) formed embryogenic callus, which differentiated
into somatic embryos within 5 weeks of culture. The somatic embryos after transfer to hormone-free regeneration medium germinated
and formed plantlets. Of the two nutrient formulations, N6 was relatively better than MS for somatic embryogenesis. A culture for 11 d on 100 μM 2,4-D was essential for the establishment
of an embryogenic callus. Shorter duration, 4-d or 7-d culture on 2,4-D medium, supported some proliferation and subsequent
differentiation into shoot-buds or multiple-shoots, in high-frequency cultures. This is first instance in monocots of a controlled
regeneration response; either somatic embryogenesis or shoot formation.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
17.
Summary The effect of 2,4-dichlorophenoxyacetic acid (2,4-D) on the regeneration from hypocotyl protoplasts ofBrassica oleracea was studied by varying the 2,4-D concentration in the protoplast culture medium, 8 p, and the callus proliferation medium, K3. When hypocotyl protoplasts of the inbred line BL12 were cultured in the complete absence of 2,4-D, they divided and produced embryogenic calli. Moreover, these calli generated somatic embryos which were easily recognized by red cotyledons due to the presence of anthocyanin. When 2,4-D was present either in 8p medium or K3 medium the formation of somatic embryos was reduced. On the other hand, the number of shoot-forming calli increased considerably. We therefore conclude that 2,4-D directs the mode of regeneration by suppressing somatic embryogenesis in favour of shoot regeneration. Secondly, 2,4-D increases the regeneration efficiency. Furthermore, the callus proliferation phase on K3 medium is most important with respect to the determination of either somatic embryogenesis or shoot regeneration.Abbreviations BA
benzyladenine
- 2,4-D
2,4-dichlorophenoxyacetic acid
- IAA
indole acetic acid
- NAA
naphthalene acetic acid
- PE
plating efficiency 相似文献
18.
Sandra Correia Ana Estefânia Cunha Lígia Salgueiro Jorge M. Canhoto 《Plant Cell, Tissue and Organ Culture》2012,109(1):143-152
Somatic embryogenesis induction and somatic embryo development of the solanaceous tamarillo tree were previously established
and successfully used for plant regeneration from different explants and varieties. Somatic embryogenesis was induced in Murashige
and Skoog medium containing 2,4-dichlorophenoxyacetic acid (2,4-D) or picloram and high sucrose concentrations (0.25 M). The
embryogenic tissues were transferred to an auxin-free medium, with reduced sucrose levels, to permit embryo development and
conversion into plantlets. This two-step protocol is often impaired by an ineffective transition from the proembryogenic masses
to embryo development. In this work, attempts to optimize the somatic embryogenesis system of tamarillo by improving the quality
of somatic embryo and embryo conversion were carried out. The results showed that the presence of a high number of abnormal
somatic embryos did not significantly inhibit plant conversion, hence indicating that shoot apical meristem development was
not affected in abnormal somatic embryos. It was also shown that the manipulation of sucrose concentration in the development
medium (0.11 M) and dark conditions before conversion increased the number of morphologically normal somatic embryos. The
comparison between mature cotyledonary zygotic and somatic embryos showed an inefficient accumulation of storage compounds,
mainly lipids, in somatic embryos. These reduced levels of lipid storage could be responsible for the abnormal patterns of
embryo development found in tamarillo somatic embryos. 相似文献
19.
Ontogeny of somatic embryos of grapevine (Vitis vinifera) produced from solid- and liquid-culture-derived proembryogenic masses (PEM) was compared using light and scanning electron microscopy. Somatic embryos produced from solid-medium-derived PEM (SPEM) had large cotyledons, little or no visible suspensor structure, and a relatively undeveloped concave shoot apical meristem, whereas those from liquid-medium-derived PEM (LPEM) had smaller cotyledons, a distinct suspensor, and a flat-to-convex shoot apical meristem. The convex shoot apical meristem in LPEM-derived somatic embryos formed as early as the heart stage of development; it was 4-6 cell layers deep and rich in protein. Suspensors persisted in fully developed and mature LPEM-derived somatic embryos. The SPEM-derived somatic embryos exhibited dormancy, as do mature zygotic embryos, which also have a rudimentary suspensor, whereas LPEM-derived embryos were not dormant. We hypothesize that the presence of a persistent suspensor in LPEM-derived somatic embryos modulates development, ultimately resulting in rapid germination and a high plant-regeneration rate. 相似文献
20.
Summary In leek (Allium ampeloprasum L.) a cyclic system of somatic embryogenesis was developed. Somatic embryos used for cyclic embryogenesis were able to develop the same type of embryogenic callus as zygotic embryos in the primary cycle. For the first time a comparison of the efficiencies of both expiants was made. Ten families were investigated for somatic embryogenesis. There was a genetic relationship with respect to somatic embryo production between the reciprocal crosses. From each family one genotype was selected for investigating cyclic somatic embryogenesis. Different levels of somatic embryo production were found between the expiants of zygotic and somatic embryos. The two best genotypes, 92.001-03 and 92.002-33 produced twice as many somatic embryos as the overall average. On average, 56% of the somatic embryos finally developed into greenhouse plantlets.Abbreviations 2,4-D
2,4-dichlorophenoxyacetic acid
- BA
6-benzyladenine
- MS medium
Murashige and skoog (1962) basal medium 相似文献