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1.
Monika Gösslová Hana Svobodová Helena Lipavská Jana Albrechtová Dick Vreugdenhil 《In vitro cellular & developmental biology. Plant》2001,37(1):24-28
Summary The carbohydrate status of developing seeds of Picea abies was examined in order to provide a frame of reference for the evaluation of changes in carbohydrate content in maturing somatic
embryos of the same species. Samples were taken at weekly intervals from 12 May 1998 (estimated time of pollination) until
20 October 1998. The total non-structural carbohydrate content was high (≈150–180 μg mg−1 dry weight) at the time of the first samples and the carbohydrate spectrum consisted of sucrose, glucose, fructose, and pinitol.
A dramatic decrease in carbohydrate content took place from June 6 onwards, that was accompanied by changes in carbohydrate
partitioning to favor sucrose over hexoses and the disappearance of pinitol. Raffinose and stachyose were first detected on
July 28, and their content gradually increased thereafter. Isolated embryos and remaining megagametophytes were analyzed starting
with September 1. Carbohydrate content was higher in isolated zygotic embryo than in the rest of the seed, with a slowly increasing
fraction of raffinose and stachyose. Comparisons of presented data with the results of our previous study of somatic embryo
carbohydrate status (Lipavská et al., 2000) revealed the following common features: (1) a decrease in total carbohydrate content
and (2) an increase in sucrose:hexose ratios in developing seeds and embryonal suspensor mass. Marked differences were observed
in carbohydrate spectra: (1) somatic embryo development was not accompanied by pinitol accumulation in any phase; (2) mature
zygotic embryos, in contrast to mature somatic embryos, contained raffinose and stachyose. These observations will provide
a solid basis for improvement of protocols for somatic embryogenesis in Picea. 相似文献
2.
Soluble sugar content of white spruce (Picea glauca) seeds during and after germination 总被引:2,自引:0,他引:2
In white spruce ( Picea glauca [Moench.] Voss.) seeds, the raffinose family oligosaccharides (RFOs) provide carbon reserves for the early stages of germination prior to radicle protrusion. Some seedlots contain seeds that are dormant, failing to complete germination under optimal conditions. Since dormancy may be imposed through a metabolic block in reserve mobilization, the goal of this project was to identify any impediment to RFO mobilization in dormant relative to nondormant seeds. Desiccated seeds contain primarily, and in order of abundance on a molar basis, sucrose and the first 3 members of the RFOs, raffinose, stachyose and verbascose. Upon radicle protrusion at 25°C, the contents of RFOs decreased to low amounts in all seed parts, regardless of prior dormancy status and sucrose was metabolized to glucose and fructose, which increased in seed parts. During moist chilling at 4°C, RFO content initially decreased before stabilizing and then increasing. In seeds that did not complete germination, the synthesis of RFOs at 4°C favored verbascose, so that at the end of 14 (nondormant) or 35 (dormant) weeks, verbascose contents in megagametophytes exceeded the amount initially present in the desiccated seed. This was also true in the embryos of the dormant seedlot. In seed parts from both seedlots after months of moist chilling, stachyose amounts exceeded raffinose amounts. Upon radicle protrusion at 4°C, RFO contents decreased to amounts most similar to those present in seeds that completed germination at 25°C. Hence, the RFOs are utilized as a source of energy, regardless of the temperature at which white spruce seeds complete germination. Based on the similarity of sugar contents in seed parts between dormant and nondormant seeds that did not complete germination, differences in sugar metabolism are probably not the basis of dormancy in white spruce seeds. 相似文献
3.
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
4.
Effects of Desiccation, Medium Osmolarity and Abscisic acid on the Maturation of Hevea brasiliensis Somatic Embryos 总被引:3,自引:0,他引:3
ETIENNE H.; MONTORO P.; MICHAUX-FERRIERE N.; CARRON M. P. 《Journal of experimental botany》1993,44(10):1613-1619
The effects of desiccation of Hevea somatic embryos and of sucroseand ABA concentrations in the maturation medium on their germinabilitywere investigated. Conversion into plant, water and histochemicalstatus of somatic embryos were compared systematically to thoseof the zygotic embryos used as reference. Slow desiccation ormaturation on 351 mol m3 sucrose supplemented with 1mmol m3 ABA strongly improved germinability and conversionof embryos into plants. The combination of the two treatmentswas the most effective, increasing the germination frequencyby 3·7 and plant conversion by 6·6 in clone PR107. Each of these two treatments increased the vigour of somaticembryos, stimulated the formation of root and shoot meristemsand the synthesis and accumulation of starch and protein reserves.At the end of maturation, the Hevea somatic embryos bore ananatomical and histochemical resemblance to mature zygotic embryos.Likewise, the two treatments brought the water status of somaticembryos closer to that of the mature zygotic embryos, but withoutachieving a perfect match. Optimization of the successful conversioninto plants may require full acquisition of this water status. Key words: ABA, embryo maturation, Hevea, somatic embryogenesis, water status 相似文献
5.
Rosete Pescador Gilberto B. Kerbauy Jane E. Kraus Wagner de Melo Ferreira Miguel Pedro Guerra Rita de Cássia L. Figueiredo-Ribeiro 《In vitro cellular & developmental biology. Plant》2008,44(4):289-299
Comparative analysis of zygotic and somatic embryogenesis of Acca sellowiana showed higher amounts of sucrose, fructose, raffinose, and myo-inositol in zygotic embryos at different developmental stages than in corresponding somatic ones. These differences were
mostly constant. In general, glucose levels were significantly lower than the other soluble carbohydrates analyzed, showing
minor variation in each embryo stage. Despite the presence of sucrose in the culture medium, its levels conspicuously diminished
in somatic embryos compared with the zygotic ones. Raffinose enhanced parallel to embryo development, regardless of its zygotic
or somatic origin. Analysis of the soluble carbohydrate composition of mature zygotic cotyledon used as explant pointed out
fructose, glucose, myo-inositol, sucrose, and raffinose as the most important. Similar composition was also found in the corresponding somatic cotyledon.
Total soluble carbohydrates varied inversely, decreasing in zygotic embryos and increasing in somatic embryos until the 24th
d, at which time they increased rapidly about sixfold in zygotic embryos until the 27th d, a period coinciding with the zygotic
proembryos formation. Such condition seems to reflect directly the variation of endogenous sucrose level, mainly because glucose
and fructose diminished continuously during this time period. This means that, in terms of soluble sugars, zygotic embryo
formation occurred under a situation represented by high sucrose amounts, simultaneously with low fructose and glucose levels,
while in contrast, somatic embryo formation took place under an endogenous sugar status characterized by a substantial fructose
enhancement. Starch levels increased continuously in zygotic embryos and decreased in somatic ones, the reverse to what was
found in fructose variation. Starch accumulation was significantly higher in somatic torpedo and cotyledonary embryos than
in the corresponding zygotic ones. 相似文献
6.
Effect of Abscisic Acid, Osmoticum, and Desiccation on Synthesis of Storage Proteins during the Development of White Spruce Somatic Embryos 总被引:10,自引:0,他引:10
The effect of abscisic acid (ABA), non-permeating osmoticumand desiccation treatment on storage protein synthesis duringmaturation of somatic embryos of Picea glauca (Moench) Voss.was examined. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis(SDS-PAGE) and Western blot analysis demonstrated that someof the major crystalloid and matrix polypeptides were absentfrom somatic embryos maturing on medium containing ABA and lowosmoticum. However, treatment with polyethylene glycol-4000(PEG) in combination with ABA resulted in the synthesis of aspectrum of storage polypeptides resembling that of mature zygoticembryos. These storage proteins accumulated throughout an 8-weekculture period, resulting in a threefold higher protein contentthan somatic embryos maturing for the same time in the absenceof PEG. The structure and distribution of protein bodies incells of these osmotically treated somatic embryos was similarto that in cells of mature zygotic embryos. Treatment with 5·0-7·5%PEG prevented catabolism of the accumulated storage polypeptidesduring desiccation. The optimal culture conditions for somaticembryo maturation and storage protein deposition was 16 µMABA and 7·5% PEG for 8 weeks followed by desiccation.Analysis of mRNAs by in vitro translation and immunoprecipitationof translated products showed that the crystalloid protein mRNAprofiles of zygotic and those of somatic embryos maturing on16 µM ABA in the absence of PEG were similar. The differencesobserved in the pattern of accumulated polypeptides in thesesomatic embryos and those of mature zygotic embryos, therefore,indicates that storage-protein synthesis in response to osmoticumis in part regulated at the translational level. During regenerationof somatic embryos to plantlets the storage polypeptides wererapidly utilized in a manner similar to that in zygotic seedlings.Copyright1993, 1999 Academic Press Desiccation, osmotic stress, storage proteins, Picea, embryogenesissomatic, mRNA (crystalloid protein) 相似文献
7.
Mass increases in raffinose family oligosaccharides (RFOs, α 1,6-galactosyl extensions of sucrose) are well documented in the generative tissues of many plants upon cold acclimation, and they (i.e. mainly the two shortest RFO members, raffinose and stachyose) have been suggested as frost stress protectants. Our focus here was on the longer RFO members as they commonly occur in the frost-hardy evergreen labiate Ajuga reptans in its natural habitat, and accumulate to their highest concentrations in winter when the plant is faced with sub-zero temperatures. We examined the effects of RFO concentration and chain length on frost tolerance using excised leaves which accumulate long-chain RFOs under both cold and warm conditions, thereby uncoupling the acclimation temperature from RFO production. We demonstrated that frost tolerance in excised A. reptans leaves correlates positively with long-chain RFO accumulation under both acclimation temperatures. After 24 d post-excision in the warm, the leaves had increased their RFO concentrations (mainly long-chain RFOs) 22-fold to 78 mg g−1 fresh weight, and decreased their EL50 values (temperature at which 50% leakage occurred) from −10.5 to −24.5 °C, suggesting a protective role for these oligosaccharides in the natural frost tolerance of A. reptans . 相似文献
8.
Expression of a GALACTINOL SYNTHASE gene is positively associated with desiccation tolerance of Brassica napus seeds during development 总被引:1,自引:0,他引:1
Desiccation tolerance of seeds is positively correlated with raffinose family oligosaccharides (RFOs). However, RFOs’ role in desiccation tolerance is still a matter of controversy. The aim of this work was to monitor the accumulation of RFO during acquisition of desiccation tolerance in rapeseed (Brassica napus L.). Rapeseeds become desiccation tolerant at 21-24 d after flowering (DAF), and the time was coincident with an accumulation of raffinose and stachyose. A gene encoding galactinol synthase (GolS; EC2.4.1.123), involved in RFO biosynthesis, was cloned and functionally characterized. Enzymatic properties of recombinant galactinol synthase were also determined. Accumulation of BnGOLS-1 mRNA in developing rapeseeds was concomitant with dry weight deposition and the acquisition of desiccation tolerance, and was concurrent with the formation of raffinose and stachyose. The physiological implications of BnGOLS-1 expression patterns in developing seeds are discussed in light of the hypothesized role of RFOs in seed desiccation tolerance. 相似文献
9.
Plant regeneration was achieved through direct and indirect somatic embryogenesis in Eucalyptus camaldulensis. Callus was induced from mature zygotic embryos and from cotyledon explants collected from 10, 15, 25, and 30-day-old seedlings
cultured on Murashige and Skoog (MS) basal medium supplemented with different concentrations of naphthaleneacetic acid (NAA).
Maximum callus induction from mature zygotic embryos was obtained on MS basal medium containing 1 mg l−1 NAA. The frequency of callus development varied based on the age of the cotyledon explants 10-day-old explants giving highest
percentage on MS basal medium supplemented with 1 mg l−1 NAA. Callus obtained from mature zygotic embryos gave highest frequency of somatic embryogenesis on MS basal medium containing
0.5 mg l−1 benzyladenine (BA) and 0.1 mg l−1 NAA. Separate age wise culture of the calli, obtained from cotyledons of different ages cultured separately, revealed high
somatic embryogenic potential on callus from 10-day-old cotyledons. Direct somatic embryogenesis too was obtained from hypocotyl
explants without an intervening callus phase on MS basal medium containing 0.5 mg l−1 BA. The effects of abscisic acid (ABA), sucrose, and different strengths of MS medium on somatic embryo maturation and germination
were also investigated. Number of mature somatic embryos increased with lower concentrations (0–1 mg l−1) of ABA while no significant differences were observed at higher concentrations (2–5 mg l−1) of ABA. Compared to basal medium containing lower concentrations of sucrose (1%), the MS medium supplemented with higher
levels of sucrose (4%) showed significantly lower frequency of mature somatic embryos. Basal medium without any dilution gave
the highest number of immature embryos. However, the number of mature embryos was high at higher medium dilutions. 相似文献
10.
Mark L. Dahmer David F. Hildebrand Glenn B. Collins 《In vitro cellular & developmental biology. Plant》1992,28(2):106-114
Summary The relative maturity and competence of somatic embryos is often estimated on the basis of their morphologic similarity to
various stages of immature zygotic embryo development. Morphologic abnormalities noted in soybean [Glycine max (L.) Merr.] somatic embryos are similar to those observed in zygotic embryos maturing in vitro and may reflect common interruptions
of normal developmental processes. We provide here a more objective means of assessing the point(s) at which cultured embryos
deviate from the normal embryogenical pathway by comparing the accumulation of the embryo-specific marker proteins (11S and
7S storage globulins, soybean agglutinin, and seed lipoxygenase) between somatic and immature zygotic embryos maturing in
culture to zygotic embryos maturingin planta. Immature (heart-stage) soybean (cv. ‘McCall’) zygotic embryos were removed from the testa and cultured for 5, 15, or 45
days in nien modified Linsmaer-Skoog salts, 5% sucrose liquid medium. Somatic embryos were induced from immature cotyledon
explants on a medium containing either naphthalene acetic acid or 2,4 dichlorophenoxyacetic acid (10 mg·liter−1). The measured level of the marker proteins present in cultured embryos never exceeded those observed in mature soybean seeds.
During the culture period, immature zygotic embryos accumulated significant levels of all marker proteins except a 29 kDa
soybean agglutinin associated with the final stages of seed maturationin planta. Somatic embryos of all morphologic classes exhibited similar levels of the marker proteins suggesting that morphology may
not accurately represent the developmental state of the culture-derived embryos. Somatic embryos induced on naphthalene acetic
acid-containing medium accumulated detectable levels of all maturation-specific marker proteins except the 7S β and 29-kD
soybean agglutinin antigen and seemed similar in most respects to the cultured zygotic embryos. Embryos induced on 2,4-dichlorophenoxyacetic
acid accumulated none of the mature 7S or 11S storage globulin subunits nor any soybean agglutinin antigen, and yet the synthesis
of 7S and 11S precursor polypeptides was similar in both naphthalene acetic acid-and 2,4-dichlorophenoxyacetic acid-induced
somatic embryos. These observations are consistent with the view that embryos induced on high 2,4-dichlorophenoxyacetic are
arrested at a relatively earlier developmental stage than naphthalene acetic acid-induced embryos of similar morphology and
may indicate that some external signal (e.g., abscisic acid or desiccation or both) is necessary for the transition to the
late maturation stage of seed ontogeny. 相似文献
11.
Marie-Anne Lelu-Walter Michèle Bernier-Cardou Krystyna Klimaszewska 《Plant Cell, Tissue and Organ Culture》2008,92(1):31-45
Several factors affecting somatic embryogenesis (SE) in Pinus sylvestris from self- and cross-pollinated seed families were studied with the aim of producing large quantities of clonal plants. Somatic
embryogenesis initiation from zygotic embryos was improved on a medium with lower than standard concentrations of 2,4-dichlorophenoxyacetic
acid (2.2 vs. 9.5 μM) and 6-benzyladenine (2.2 vs. 4.5 μM). On this medium, initiation rates of four controlled crosses, including
one self-cross, varied from 3% to 25%. Among the maturation factors tested, the concentration of abscisic acid (ABA 80, 120 μM)
had no significant effect on the production of mature somatic embryos when the medium contained 0.1 M sucrose. When sucrose
concentration was 0.2 M, however, 1.4 times more mature somatic embryos were produced on medium with 80 μM compared with 120 μM
ABA. Under our best maturation conditions, mature somatic embryos accumulated amounts of storage proteins that were similar
to the amounts in mature zygotic embryos. Activated charcoal exerted a beneficial effect on mature somatic embryo production
of 24-week-old cultures; there was no evidence of such an effect in 8-week-old cultures. Thirty-seven embryogenic lines from
a self-cross and an out-cross were chosen for clonal plant production. Highly embryogenic lines produced mature somatic embryos
that were more likely to convert to plants than those from less embryogenic lines. After 4 months of growth in a shade house,
plantlet survival rates exceeded 70% for 31 lines out of 35. This report describes an improved method for accelerated production
of large quantities of Scots pine for clonal tests. 相似文献
12.
Encapsulated cocoa (Theobroma cacao L.) somatic embryos subjected to 0.08–1.25 M sucrose treatments were analyzed for embryo soluble sugar content, non-freezable
water content, moisture level after desiccation and viability after desiccation and freezing. Results indicated that the higher
the sucrose concentration in the treatment medium, the greater was the extent of sucrose accumulation in the embryos. Sucrose
treatment greatly assisted embryo post-desiccation recovery since only 40% of the control embryos survived desiccation, whereas
a survival rate of 60–95% was recorded for embryos exposed to 0.5–1.25 M sucrose. The non-freezable water content of the embryos
was estimated at between 0.26 and 0.61 g H2O g−1dw depending on the sucrose treatment, and no obvious relationship could be found between the endogenous sucrose level and
the amount of non-freezable water in the embryos. Cocoa somatic embryos could withstand the loss of a fraction of their non-freezable
water without losing viability following desiccation. Nevertheless, the complete removal of potentially freezable water was
not sufficient for most embryos to survive freezing. 相似文献
13.
14.
K. Pomeroy D. C. W. Brown Y. Takahata 《In vitro cellular & developmental biology. Plant》1994,30(4):196-203
Summary Microspore-derived embryos fromBrassica napus cv. Topas (low erucic acid) and Reston (high erucic acid) were subjected to treatment with abscisic acid (ABA) during late-stage
embryo development and then dried under controlled relative humidities to mature dry seed levels of moisture. Exogenously
medium-supplied ABA arrested growth and development, reduced moisture content, increased total fatty acids on a dry weight
basis, and stimulated systhesis of proteins in microspore-derived embryos. ABA also resulted in a higher proportion of 22∶1
in cv. Reston (high 22∶1) and increased the level of fatty acid unsaturation in cv. Topas (low 22∶1). The accumulation of
two proteins that co-migrated with cruciferin and napin on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and two-dimensional
gels were also promoted by exposure to ABA, and the degree of accumulation was dependent on the concentration and time of
application of ABA. Controlled desiccation of microspore embryos, used to simulate normal maturation and dehydration of zygotic
embryos during seed development, did not seem to cause an increase of either storage proteins, total fatty acids, or 22∶1
(in cv. Reston), suggesting that dehydration is not a prerequisite for these processes, at least in culturedBrassica embryos. 相似文献
15.
Mohammed A. M. Aly Essam A. Amer Wasef A. Al-Zayadneh Alaa E. Negm Eldin 《Plant Cell, Tissue and Organ Culture》2008,95(1):107-114
Inducing somatic embryogensis from jojoba [Simmondsia chinensis (Link) Schneider] explants to produce artificial seeds in the laboratory (in vitro) may prove highly profitable, as the seeds
contain a characteristic liquid wax of economic importance in industry, nutrition and medicine. Thus, there is a need to examine
the effect of the factors involved in the in vitro process on the quality and quantity of the synthesized fatty acids in comparison
with those naturally produced in vivo. Immature zygotic embryos and mature leaf explants were cultured on Murashige and Skoog
basal medium (MS) supplemented with various levels of 2,4-D, BA and sucrose. Embryogenic calluses developed from the zygotic
embryos and leaf explants over a period of 2–4 weeks with the highest response at 0.4 μM 2,4-D, 2.2/4.4 μM BA and 117 mM sucrose
(4%). Following induction, the zygotic embryo derived somatic embryos developed to the globular, heart, torpedo, and cotyledon
stages. Direct somatic embryogenesis was observed with some of the zygotic embryo explants. Leaf-derived embryogenic calluses
did not mature on any of the maturation/germination media examined up to 4 weeks of culture. Analysis of fatty acids indicated
that the mature seeds are characterized with long chain saturated fatty acids C22:0 behenic Acid. The zygotic embryo-derived
somatic embryos (SE-Z) and leaf-derived somatic embryos (SE-L) are characterized with the induction of the essential polyunsaturated
fatty acid C18:2 (omega-6) linoleic acid, (omega-3) alpha-linolenic acid (ALA), with higher values of long chain saturated
fatty acids C16:0 palmitic acid and monounsaturated fatty acid C18:1 oleic acid. These results indicate that manipulating
the growth regulators in the induction media influenced the fatty acids synthesis and hence the fatty acids profile in jojoba
somatic embryos. 相似文献
16.
The limit of permeability of white spruce (Picea glauca [Moench.]Voss) somatic embryo cell walls to molecules was in the orderof 30 . Polyethylene glycols (PEGs) and dextrans of molecularweights greater than 1000 and 6000, respectively, produced anonpermeating (non-plasmolysing) water stress which improvedembryo development. Somatic embryos converted to plantlets atfrequencies of 7684% following slow drying and storageat 20 C for 1 year, which was similar to the 77% recordedfor control somatic embryos slowly dried then germinated withoutfreezing or storage. Culture for 78 weeks with mediumcontaining abscisic acid, 3% sucrose, and 7.5% PEG 4000 yieldedsomatic embryos with five times the embryo storage lipid contentrecorded for zygotic embryos. During culture with PEG the moisturecontent of the somatic embryos decreased from 96% for immaturesuspension-cultured somatic embryos, to 47% for mature embryos.Somatic embryos cultured for 78 weeks survived rapiddrying to 5% moisture content, and converted to plantlets atfrequencies of 6070%, but no somatic embryos survivedrapid drying when cultured for only 4 weeks; however, slow dryingdid induce desiccation tolerance in 3-week cultured somaticembryos. Abscisic acid was important to maintain embryos ina developmental state, but ABA alone did not induce desiccationtolerance. In order to induce desiccation tolerance a waterstress treatment was required. Tolerance of rapid drying coincidedwith moisture contents below 55%, which occurred after 5 weeksof culture in the presence of PEG 4000 and abscisic acid. Key words: Dextran, molecular weight, polyethylene glycol, triacylglycerol, water stress 相似文献
17.
A non-plasmolysing moisture stress effected by polyethyleneglycol (PEG) was beneficial when applied to maturing white spruce(Picea glauca) somatic embryos for the following reasons. Anosmotic treatment of 5.07.5% PEG stimulated a threefoldincrease in the maturation frequency. The osmotically treatedsomatic embryos displayed higher dry weights and lower moisturecontents than the controls, indicating a greater accumulationof storage reserves. Moisture contents of mature, osmotically-treated,hydrated somatic embryos were 4045%, in contrast to 57%for the non-osmotically treated controls. Desiccation was achievedby placing the somatic embryos in a range of relative-humidityenvironments. No clear trend for the effect of PEG on survivalof desiccated somatic embryos was observed; mean survival valuesranged from 34 to 62% when somatic embryos from all osmotictreatments were desiccated for 14 d at 81% relative humidity.Following this desiccation treatment, somatic embryos from allosmotic concentrations had moisture contents of 2631%,similar to the 32% recorded for unimbibed zygotic embryos. Afterimbibition, moisture contents for these zygotic and somaticembryos were in the order of 60%. Somatic embryos matured withPEG remained quiescent during desiccation due to their low initialmoisture contents, and gave rise to plantlets of normal appearance.Gradual desiccation of the somatic embryos directly followingmaturation with abscisic acid (ABA) was crucial to survivalduring desiccation. A plasmolysing water stress effected bysucrose at osmotic potentials similar to PEG was detrimentalto somatic embryo maturation, thereby emphasizing the importanceof the choice of osmoticum. Desiccation, maturation, osmotic potential, Picea glauca, polyethylene glycol, somatic embryo, water stress, white spruce 相似文献
18.
We used four cultivars ofCapsicum annuum L.—Sweet Banana, California Wonder, Yolo Wonder, and Ace—to reexamine the critical factors influencing somatic embryogenesis
from zygotic embryo explants, as reported in the literature. When we followed the protocol of Buyukalaca and Mavituna (1996),
which had induced somatic embryogenesis from mature zygotic embryos of cv. Ace, only callus was formed without embryogenesis
from our mature zygotic embryo expiants. Using the procedures of Harini and Lakshmi Sita (1993) and Binzel et al. (1996),
with some modifications, we were able to induce somatic embryogenesis in all four cultivars. Rates of conversion were significantly
reduced, from 75% and 65% to 40% and 28% in ’Sweet Banana’ and ’California Wonder’, respectively, when the immature zygotic
embryo expiants were held on the induction medium for longer than two weeks. Likewise, somatic embryogenesis of ’Yolo Wonder’
was not observed if the induction medium was supplemented with 10% glucose or fructose, or without 10% sucrose. For somatic
embryo induction and eventual plantlet conversion in Yolo Wonder’, maltose could adequately replace sucrose. In all four cultivars,
somatic embryos were initiated from immature zygotic explants on media with or without coconut water, under both light and
dark conditions. 相似文献
19.
The role of soluble sugars in desiccation tolerance was investigated in seeds of two species from the genus Acer: Norway maple (Acer platanoides L.) — tolerant and sycamore (Acer pseudoplatanus L.) — intolerant to dehydration. During two years of observations it was found that seeds of Norway maple acquire desiccation
tolerance at the end of August i.e. about 125 days after flowering (DAF). During seed development, the transition from intolerant
to tolerant state in Norway maple seeds was accompanied by the accumulation in seed tissues of raffinose, stachyose and sucrose.
The sucrose/raffinose ratio in Norway maple seeds was lower than in sycamore. In mature Norway maple seeds sucrose and raffinose
contents were higher than in sycamore. It was concluded, that soluble sugars such as sucrose, raffinose and stachyose may
play an important role in desiccation tolerance and/or intolerance of Norway maple and sycamore seeds. Differential thermal
analysis (DTA) was used to study the relationship between desiccation sensitivity and the state of water in seed tissues.
The level of non-freezable water was the same in both analysed seed species, but the temperature of water crystallization
during desiccation was lower in sycamore seeds. 相似文献
20.
Lipid composition of somatic and zygotic embryos from Prunus avium. Effect of a cold treatment on somatic embryo quality 总被引:1,自引:0,他引:1
Lydia Reidiboym-Talleux Martine Sourdioux Emmanuel Grenier Ghislaine Grenier-De March 《Physiologia plantarum》2000,108(2):194-201
In order to evaluate the quality of Prunus avium somatic embryos, a comparison of lipid composition between somatic and zygotic embryos was undertaken. In both zygotic and somatic embryos, neutral glycerolipids (NL) and phosphatidylcholine (PC) were the 2 major lipid classes. The content of NL increased over the course of development in zygotic embryos and reached 490 μg per embryo, while the PC content reached 100 μg per embryo. However, the contents of NL and PC in somatic embryos were similar to immature zygotic embryos at stage 3. Fatty acid composition of NL from both zygotic and somatic embryos revealed more unsaturated than saturated fatty acids. In somatic embryos, the saturated/unsaturated fatty acid ratios of NL and phosphatidylinositol (PI) were similar to those observed in immature zygotic embryos up to stage 6. Conversely, in phosphatidylethanolamine (PE) the ratio was similar to the ratio observed in mature zygotic embryos, at stage 7. Histological studies confirmed the immaturity of somatic embryos: no protein or lipid reserves were observed in the vacuolated cotyledonary cells. Maturation of somatic embryos was improved by a 2-month cold period. In cold-treated somatic embryos, both NL and PC increased to levels comparable to those observed in mature zygotic embryos, and the PE content reached 10 times the level of that in mature zygotic embryos. The cold treatment induced a large increase in the saturated/unsaturated fatty acid ratio in phospholipids but only a slight increase in that of neutral glycerolipids. Histological studies revealed a lipid accumulation at cellular level. Lipid bodies surrounded by protein bodies were observed in cotyledonary cells of cold-treated somatic embryos. Furthermore, the cold-treated somatic embryos developed into plantlets with a frequency of 14%, whereas no development was obtained with the non-treated somatic embryos. 相似文献