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1.
Ethylene biosynthesis during different phases of somatic embryogenesis in Medicago sativa L. cv. Rangelander using two regeneration protocols, RPI and RPII, was studied. The highest ethylene production was detected
during callus growth on induction medium in both regeneration protocols. Significantly less ethylene was produced by embryogenic
suspension than by callus (RPII). Developing embryos synthesized higher amounts of ethylene than mature embryos. Production
of ethylene was strongly limited by the availability of 1-aminocyclopropane-1-carboxylic acid and also by ACC-oxidase activity.
However, removal of ethylene from culture vessels’ atmosphere using KMnO 4 or HgClO 4 had no significant effect on callus growth, somatic embryo induction and development. Reducing of ethylene biosynthesis by
aminoethoxyvinylglycine substantially decreased somatic embryo production and adversely affected their development, indicating
ethylene requirement during proliferation and differentiation but not induction. 相似文献
2.
The concentration of free and bound polyamines was studied during the somatic embryogenesis induction process in Coffea canephora explants. In the present study we show that when the induction of somatic embryogenesis in C. canephora is carried out under light conditions and in the presence of the plant growth regulator, benzylaminopurine, a cytokinin,
a faster response to induction is obtained . In the darkness, the response is delayed for more than 20 days, and the number of embryos is smaller. In the absence of benzylaminopurine
no embryogenic response was observed. The pronounced changes in the levels of putrescine, spermidine, and spermine, both free
and bound, found in C. canephora suggest that a close correlation exists between polyamine biosynthesis and somatic embryogenesis in C. canephora during a period of cellular differentiation associated with the induction of somatic embryogenesis.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
We would like to dedicate this paper to Dra. Estela Sánchez, the pioneer of the Plant Biochemistry in Mexico, on occasion
of her 75th anniversary. 相似文献
3.
Activity of antioxidant enzymes was evaluated during somatic embryogenesis and shoot organogenesis from cultured leaf segments
of Gladiolus hybridus Hort. The effect of exogenous antioxidants on somatic embryogenesis and shoot organogenesis has also been monitored. Activity
of superoxide dismutase (SOD) gradually increased during somatic embryogenesis. while activities of catalase (CAT) and peroxidase
(POX) decreased. In contrast, increase in CAT and POX activity and a concomitant decrease in SOD activity were noted during
shoot organogenesis. Exogenous application of antioxidants such as glutathione (GSH), α-tocopherol and ascorbate (AA) inhibited
somatic embryogenesis but stimulated shoot organogenesis. The frequency of somatic embryogenesis increased with the addition
of H 2O 2. However, H 2O 2 inhibited shoot organogenesis.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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
6.
An approach combining morphological profiling and flow cytometric analysis was used to assess genetic stability during the several steps of somatic embryogenesis in Pinus pinaster. Embryogenic cell lines of P. pinaster were established from immature zygotic embryos excised from seeds obtained from open-pollinated trees. During the maturation stage, phenotype of somatic embryos was characterized as being either normal or abnormal. Based upon the prevalent morphological traits, different types of abnormal embryos underwent further classification and quantification. Nuclear DNA content of maritime pine using the zygotic embryos was estimated to be 57.04 pg/2C, using propidium iodide flow cytometry. According to the same methodology, no significant differences ( P ≤ 0.01) in DNA ploidy were detected among the most frequently observed abnormal phenotypes, embryogenic cell lines, zygotic and normal somatic embryos, and somatic embryogenesis-derived plantlets. Although the differences in DNA ploidy level do not exclude the occurrence of a low level of aneuploidy, the results obtained point to the absence of major changes in ploidy level during the somatic embryogenesis process of this economically important species. Therefore, our primary goal of true-to-typeness was assured at this level. 相似文献
7.
This report describes the successful plant regeneration via somatic embryogenesis from immature zygotic embryos of Cryptomeria japonica D. Don. For the induction of embryogenic tissue, we determined that the optimal medium contained N 6-benzyladenine and 2,4-dichlorophenoxyacetic acid. Immature zygotic embryos that were collected at the end of June yielded embryogenic tissue at the highest frequency. Embryogenic tissues that had proliferated in liquid medium included small and loosely packed cells and elongating or elongated cells. We used ten cell lines to determine the optimal medium for the development of somatic embryos. Induced somatic embryos germinated with synchronous sprouting of cotyledons, hypocotyls and roots. Gibberellin A 3 in the germination medium had a positive effect on both the elongation of hypocotyls and the survival of seedlings. The frequencies of induction and germination of somatic embryos differed among the cell lines examined. Most of the seedlings grew normally. This system of somatic embryogenesis required 4–5 months for the regeneration of C. japonica plantlets from immature zygotic embryos.Abbreviations ABA Abscisic acid - BA N6-Benzyladenine - 2,4-D 2,4-Dichlorophenoxyacetic acid - GA3 Gibberellin A 3Communicated by F. Sato 相似文献
8.
Several coniferous species belonging to the Pinaceae family can be propagated via somatic embryogenesis, while species belonging to the Cupressaceae family cannot. The aim of this study was to identify possibilities and limitations with somatic embryogenesis in Cupressaceae. Juniperus communis was chosen as model species. We show that a high initiation frequency of embryogenic cell lines can be established from intact
megagametophytes at the time when intensive cleavage polyembryogeny takes place. The embryogenic cell lines proliferate fast
on medium lacking plant growth regulators. Early somatic embryos develop after transfer to medium with decreased content of
nitrogen and calcium. The early embryos mature after exposure to abscisic acid. Mature cotyledonary embryos germinate after
partial desiccation. A high proportion, over 40%, of the germinating embryos retain the embryogenic potential in the basal
part, resulting in development of new embryogenic tissue. 相似文献
10.
Polyamine levels and the activities of two polyamine biosynthetic enzymes, arginine decarboxylase (EC 4.1.1.19) and S-adenosylmethionine decarboxylase (EC 4.1.1.50), were determined during somatic embryogenesis of carrot ( Daucus carota L.) cell cultures. Embryogenic cultures showed severalfold increases in polyamine levels over nondifferentiating controls. A mutant cell line that failed to form embryos but grew at the same rate as the wild-type line also failed to show increases in polyamine levels, thus providing evidence that this increased polyamine content was in fact associated with the development of embryos. Furthermore, inhibition of these increases in polyamines caused by drugs inhibited embryogenesis and the effect was reversible with spermidine. The activities of arginine decarboxylase and Sadenosylmethionine decarboxylase were found to be suppressed by auxin; however, the specific effects differed between exogenous 2,4-dichlorophenoxyacetic acid and endogenous indole-3-acetic acid. The results indicate that increased polyamine levels are required for cellular differentiation and development occurring during somatic embryogenesis in carrot cell cultures.Abbreviations ADC
arginine decarboxylase
- 2,4-D
2,4-dichlorophenoxyacetic acid
- DFMA
difluoromethylarginine
- DCHAS
dicyclohexylammonium sulfate
- SAMDC
S-adenosylmethionine decarboxylase 相似文献
12.
Summary Protoplasts of navel orange, isolated from embryogenic nucellar cell suspension culture, were fused with protoplasts of grapefruit isolated from leaf tissue. The fusion products were cultured in the hormone-free medium containing 0.6 M sucrose. Under the culture conditions, somatic embryogenesis of navel orange protoplasts was suppressed, while cell division of grapefruit mesophyll protoplasts was not induced. Six embryoids were obtained and three lines regenerated to complete plants through embryogenesis. Two of the regenerated lines exhibited intermediate morphological characteristics of the parents in the leaf shape. Chromosome counts showed that these regenerated plants had expected 36 chromosomes (2n=2x=18 for each parent). The rDNA analysis using biotin-labeled rRNA probes confirmed the presence of genomes from both parents in these plants. This somatic hybridization system would be useful for the practical Citrus breeding. 相似文献
13.
To initiate somatic embryogenesis in Pinus sylvestris and Pinus pinaster, immature seeds were collected from June to August and the developmental stage of the zygotic embryos was determined. Four developmental stages were distinguished and the response of the zygotic embryos at each of the four developmental stages was compared intra- and inter-species. For this study, modified Litvay's medium (LM), with or without growth regulators, was chosen. Somatic embryogenesis was initiated and maintained on both media but the two species displayed different propensities. In P. sylvestris, the highest initiation frequency was obtained with intact megagametophytes containing embryos at the four-cell stage to the stage of cleavage polyembryony (up to 22 and 9%, respectively). The culture medium had no significant effect on the initiation and proliferation of embryogenic cultures. In P. pinaster, however, the best response occurred from excised zygotic embryos at the stage prior to elongation of cotyledon primordia (up to 40% explants responded), on medium with growth regulators. Another characteristic distinguishing the two species in culture was that in some embryogenic cell lines of P. sylvestris, somatic embryos matured spontaneously when initiated and maintained on medium without growth regulators. Some of these embryos developed into plantlets on the same medium at the frequency of 40%. Therefore, in P. sylvestris all the stages of somatic embryogenesis were achieved on the medium without growth regulators. However, in both species, maturation of a large number of somatic embryos was greatly improved on medium containing high concentration of gellan gum (Gelrite 10 g l ?1) and abscisic acid (60 μ M). Cotyledonary somatic embryos subsequently germinated (72 and 80% for P. sylvestris and P. pinaster, respectively) and developed into plantlets (48 and 29%, for P. sylvestris and P. pinaster, respectively). This represents a significant improvement in plantlet recovery from somatic embryos of both species. 相似文献
14.
为探讨巴西橡胶树( Hevea brasiliensis)自根幼态无性系与供体间差异产生的原因,应用甲基化敏感扩增多态性扩增技术,对巴西橡胶树体细胞胚发生过程中基因组DNA 胞嘧啶甲基化程度和模式进行了分析。结果表明,在巴西橡胶树体细胞胚发生过程中不同阶段的DNA 甲基化程度不同,以花药的DNA 甲基化程度最高,体细胞胚的DNA 甲基化水平最低。在体细胞胚发生过程中出现了I、Ⅱ和Ⅲ 3 种类型的甲基化多态性带型的改变,包括他们的出现与消失。因此,橡胶树体细胞胚发生过程中可能通过DNA 甲基化甲基化和去甲基化来调控基因的表达。 相似文献
15.
The effects of methyl jasmonate (MeJA) in relation to abscisic acid (ABA) on different phases of somatic embryogenesis were
studied in Medicago sativa L. Different concentrations of both the growth inhibitors (0.0, 0.5, 5.0, 50.0 and 500.0 μM) were tested in five distinct phases of somatic embryogenesis, viz., induction, proliferation, differentiation, maturation
and regeneration. Like ABA, MeJA also inhibited callus induction, callus growth, proliferation of embryogenic suspension as
well as germination and conversion of somatic embryos. However, its inhibitory effects on various phases of somatic embryogenesis
were less pronounced as compared to that due to ABA. In contrast to ABA, MeJA did not have any significant influence on the
development of somatic embryos when applied in the differentiation phase. The study showed that ABA used routinely as an inducer
of somatic embryo maturation in M. sativa could not be replaced by MeJA. 相似文献
16.
The jasmonates as well as abscisic acid were found to be inhibitors of callus growth and somatic embryogenesis in Medicago sativa L. tissue cultures. An exposure to these inhibitors during the induction as well as the differentiation stage reduced the
number of somatic embryos obtained. The jasmonates showed to be less active in the inhibition of callus growth and somatic
embryo production than abscisic acid. 相似文献
17.
Brassinolide (BR), which is the most biologically active brassinosteroid, was used to examine the potential effect of hormone
on cotton somatic embryogenesis. Ten-day-old cotton ( Gossypium hirsutum L., cv. Cooker) seedlings were used for explant source and hypocotyls were removed and cultured on MS basal medium with B 5 vitamins supplemented with 1 mg/L 6-benzylaminopurine + 0.5 mg/L kinetin for callus induction. After one month proliferating
calli pieces were collected and cultured on MS basal medium containing various concentrations of BR (0.1, 0.5, 1.0 μM) with
their controls. BR treatments were negatively effective on the fresh weight of calli when compared to control. Differential
somatic embryogenesis maturation rates due to BR treatment were observed. Somatic embryogenesis was stimulated especially
for transition to cotyledonary phase at 0.5 mg/L BR. Histological preparations from embryogenic calli and somatic embryos
at different stages of development revealed the spontaneous polyploidisation during early somatic embryogenesis on BR-treated
calli. Present results suggest that BR negatively effected calli growth, however, had a stimulating role in maturation of
somatic embryos. 相似文献
18.
Korean arbor vitae (KAV; Thuja koraiensis Nakai) is a critically endangered coniferous tree in Korea. Here, we report the somatic embryogenesis (SE) and cryopreservation system that can be used for micropropagation of KAV and long-term storage of KAV cultures. To induce SE in KAV, the influence of the developmental stage of zygotic embryos and the effect of basal medium on embryogenesis induction were examined. The developmental stage of zygotic embryos had a significant effect on the embryogenesis induction (P < 0.0001). The highest frequency of embryogenesis induction occurred in megagametophytes with zygotic embryos at precotyledonary (P) and late embryogeny (L1) stage (36%). The highest frequency of embryogenesis induction was obtained on initiation medium containing IM basal salts with 2.2 μM 6-benzylaminopurine and 4.5 μM 2,4-dichlorophenoxyacetic acid (35%). The effect of abscisic acid (ABA) on production of somatic embryos was tested. The highest number of somatic embryos per 50 mg of embryogenic tissue was achieved on maturation medium with levels of 100 μM ABA (24.0 ± 2.4). The effect of cryopreservation treatment to embryogenic tissues on the maturation capacity of somatic embryos was also tested. No significant differences between noncryopreservation and cryopreservation treatment were observed (P = 0.1896), and the highest mean number of somatic embryo per 50 mg of embryogenic tissues was obtained in noncryopreserved cell line (28.17 ± 5.66). Finally, the genetic identities of the plantlets regenerated from non- and cryopreserved embryogenic cell lines were verified and there was no genetic variation in the regenerated plantlets from cryostored embryogenic cell lines. This study is the first report on SE and the successful cryopreservation of embryogenic culture of the genus Thuja. 相似文献
19.
Summary Somatic embryogenesis from different genotypes of Asparagus officinalis L. could be obtained by in vitro culture of shoot apices. Apices were first cultured on an auxin-rich inducing medium and then transferred onto a hormone-free development medium. All genotypes tested in this way produced a few somatic embryos. In some experiments, during the development phase, a new kind of friable highly embryogenic tissue appeared in a random manner. These tissues could be continuously subcultured on a hormone-free medium and were named embryogenic lines. Five of these embryogenic lines regenerated plants from somatic embryos. These regenerated plants exhibited an increased embryogenic response compared to the parent plants; e.g. apex culture produced somatic embryos without any auxin treatments. For one of the embryogenic lines, a genetic analysis showed that the improved embryogenic response of regenerated plants was controlled by a mendelian dominant monogenic mutation.Abbreviations LSEA
low somatic embryogenesis ability
- HSEA
high somatic embryogenesis ability
- NAA
1-naphthaleneacetic acid 相似文献
20.
Plant regeneration via direct somatic embryogenesis from cotyledons, hypocotyls and leaves in seabuckthorn ( Hippophae rhamnoides L.) was achieved. The influences of basal media, carbon sources, plant growth regulators (PGRs) with different concentrations
and combinations on embryogenesis capacity of explants were studied. The highest frequency of somatic embryos production and
germination was obtained on Schenk and Hildebrandt medium (SH) supplemented with 1.0 mg dm −3 kinetin and 0.2, 0.5 mg dm −3 indole-3-acetic acid. Granulated sugar was the optimal carbon source. The embryo-derived plantlets with well-developed roots
and shoots were transferred successfully to the greenhouse with a maximum survival rate of 55 %. Histological observation
revealed that the somatic embryos were similar to those of zygotic embryos. 相似文献
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