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1.
Using seven tropical rainforest species of north Queensland, Australia, we simulated partial predation and compared the development of intact embryos and embryos from which various proportions had been removed, including in some cases the original root–shoot axis. Embryos of all species contained storage reserve cotyledons and germinate in a hypogeal manner. Species mean embryo masses ranged from 0.4–48.1 g. Partial embryo predation treatments were: ½ embryo treatment; embryos separated into component cotyledons, and ¼ embryo treatment; cotyledons separated as above and subsequently cut in half. Germination was scored as production of roots and shoots, or roots or shoots only. Embryos from all species produced seedlings in all treatments, even after the removal of up to 75 percent of the cotyledonary reserve. Moreover, the proportion germinating were not different between intact embryos and i) separated cotyledons, ii) cotyledon halves that maintained or were adjacent to the embryonic axis (except for the largest seeded species), and iii) cotyledon halves that did not include the root–shoot axis (four species). Thus, production of roots and shoots, or roots or shoots only was largely independent of the presence of the embryonic root–shoot axis – implying that somatic cells in storage cotyledons are capable of differentiating into the full range of cell types typical of shoots and roots in the absence of the root–shoot axis. The generality of this response across all seven species suggests somatic embryogenesis in storage cotyledons may be a more widespread phenomenon in tropical floras than currently considered. 相似文献
2.
Callus and suspension cell lines were derived from haploid barley embryos produced by the Bulbosum method. Embryos 1 to 2
mm long callused on medium containing a low concentration of 2,4-dichlorophenoxyacetic acid (2,4-D). Fast-growing nodular,
beige callus (Type 1), slow-growing, light brown, watery callus (Type 2) and a dense, light yellow, nodular callus (Type 3)
were recovered. Type 3 callus was embryogenic and was produced on embryos 1 to 2 mm in length. Although callus cultures gradually
became polyploid, a small proportion of haploid cells was retained and the majority of regenerated plantlets were haploid.
The organogenic potential of long-term (Type 1) callus cultures was generally low and decreased with time. Attempts to inducede
novo shoot formation in Type 1 cultures were not successful. 相似文献
3.
Summary Immature zygotic embryo has been the widely used explant source to develop embryogenic callus lines, cell suspensions and
protoplasts for transformation of cereal crops including maize, wheat, rice, oat, barley, sorghum, and millet. However, the
lack of competence of immature embryos in certain elite lines is still a barrier to rontine production of transgenic cereal
crops in certain commercial cultivars. In addition, a great deal of effort is required to produce immature embryos, manipulate
cultures, of immature embryos or their cell suspensions, and cryoperserve cultures for further use. In addition, undifferentiated
cells may have reduced regenerability after a few months, of in vitro culture. Alternative explants and regeneration systems for efficient transformation of cereal crops are needed to avoid or
reduce the above limitations. During the past decade, scientists have successfully manipulated the shoot apical meristerms
from seedlings of maize oat, sorghum, millet, wheat, and barley in an effort to develop a less genetype-dependent and efficient
cereal regneration system that can be maintained in vitro for long pertiods of time without the need for cryopreservation. Furthermore, apical mesistem regeneration systems were used
to stably transform maize, wheat, rice, oat, barley, sorghum, and millet. 相似文献
4.
Laurent Bonneau Nicole Beranger-Novat Jeannine Monin Josette Martin-Tanguy 《Plant Growth Regulation》1995,16(1):5-10
In vitro formation of roots and somatic embryos is obtained from cotyledon explants of a Spindle tree (Euonymus europaeus L.) cultured on two different media: a medium inducing callus formation and the production of roots, and a medium inducing callus formation, root and somatic embryo production. We studied the effects of α-difluoromethylornithine (DFMO), a specific, irreversible inhibitor of ornithine decarboxylase (ODC) on root and somatic embryo production, growth and titers of putrescine in Euonymus explants and explant-derived calli. Early changes in putrescine levels were detected in both cultures before the visible emergence of roots or somatic embryos. DFMO rapidly inhibited putrescine accumulation and growth in non-embryogenic calli and highly stimulated rooting activity. DFMO partially inhibited putrescine accumulation in embryogenic calli. This inhibition had no effects on callus growth but significantly reduced the time of emergence of roots and highly stimulated somatic embryo production. The relationship among putrescine, putrescine metabolism, growth, root and somatic embryo formation is discussed. 相似文献
5.
《Plant science》1987,51(1):77-81
Significant variation among Chinese Spring wheat (Triticum aestivum L.) and a set of seven addition lines in which chromosomes from rye (Secale cereale L.) were incorporated into the Chinese Spring background was observed for callus formation and plant regeneration from anther cultures and for plant regeneration from immature embryo cultures. Callus initiation from immature embryo cultures was uniformly high. Rye chromosome 4 contains factors which significantly increase both anther culture responses relative to Chinese Spring. Rye chromosomes 6 and 7 both contain positive factors for regeneration from immature embryo culture. While no correlation was found between anther culture and embryo culture responses, a positive correlation was observed between the two anther culture response variables. 相似文献
6.
Summary Callus induction, adventitious shoot and root formation, and somatic embryogenesis were investigated in root, cotyledon and mesocotyl cultures ofBellevalia romana (L.) Rchb. grown on a synthetic nutrient medium containing different plant hormones. The combination of naphtaleneacetic acid plus benzylaminopurine was very effective in causing callus growth and plant regeneration from mesocotyl explants. On the contrary 2,4-dichlorophenoxyacetic acid caused suppression of shoot bud development in the same type of callus. Both cotyledon and root derived calli showed a low growth rate and did not regenerate shoots but only roots. Differentiation of somatic embryos which eventually developed into plantlets was promoted by 2,4-dichlorophenoxyacetic acid in suspension cultures. The results are discussed in relation to studies on nuclear behaviour during different morphogenetic pathways. 相似文献
7.
Deborah A. Cook Debra M. Decker John L. Gallagher 《Plant Cell, Tissue and Organ Culture》1989,17(2-3):111-119
Organogenic callus cultures of seashore mallow, Kosteletzkya virginica (L.) Presl., originated from excised mature embryos or stem sections of aseptically germinated plants initially cultured on Murashige & Skoog minimal organics medium containing 30000 mg l-1 glucose, 2.0 mg l-1 indoleacetic acid and 1.0 mg l-1 kinetin. Plants were regenerated via shoots and roots from callus cultures following transfer through a series of media with different cytokinin/auxin ratios and changes in carbohydrate source. Meristematic regions, shoot and root primordia were observed during histological examination of the tissues. Somatic embryos were not found. 相似文献
8.
There is a certain frequency of fertilization and embryo productivity in naked oat (Avena nuda L. ) × maize (Zea mays L. ) crosses. The maize pollen readily germinated on the naked oat stigma and more than one pollen tubes grew into the style in about 68% of florets. In a sample of 163 florets fixed after pollination, 5 (3.07%) had only an embryo, 3 (1.84%) had only an endosperm and 10 (6.13%) had both. Overall, 9 haploid and 3 diploid naked oat plants were obtained from 12 seeds which formed following application of maize pollen to about 2200 emasculated naked oat florets. Preliminary studies indicated that elimination of the maize chromosomes occurred early in the embryo and endosperm development. This method gives a new approach for obtaining haplo!d naked oat. 相似文献
9.
When cotyledonary explants, excised from in vitro germinated seedlings, of pomegranate (Punica granatum L.) were incubated on solid Murashige and Skoog (1962) medium supplemented with 21 μM naptheleneacetic acid (NAA) and 9 μM 6-benzyladenine (BA), 80% of explants developed callus.
A high frequency of shoot organogensis was obtained when explants were incubated on MS medium supplemented with 8 μM BA, 6 μM
NAA, and 6 μM giberrellic acid (GA3). However, adding 24 μM silver nitrate (AgNO3) to this medium markedly enhanced shoot regeneration frequency (63%) and mean number of shoots per explant (11.26) and length
of shoots (2.22 cm). Highest frequency of in vitro rooting, mean number of roots/shoot (4.32), and mean root length (2.71 cm)
were obtained when regenerated shoots were transferred to half-strength MS medium supplemented with 0.02% activated charcoal.
Well-rooted plantlets were acclimatized, and then transferred to soil medium. Moreover, when zygotic embryos of P. granatum, excised from seeds collected at 16 weeks following full bloom, were incubated on MS medium containing 30 g l−1 sucrose, 15% coconut water, 21 μM NAA, and 9 μM BA, they developed the highest frequency of embryogenic callus, clumps with
globular embryos, and mean number of both globular and heart-shaped embryos per callus clump. Subjecting zygotic embryo explants
to six-week dark incubation period was essential for embryogenic callus induction, and these were subsequently transferred
to 16 h photoperiod for further growth and development of somatic embryos. Germination of somatic embryos was observed when
these were transferred to MS medium was supplemented with 60 g l−1 sucrose. 相似文献
10.
A Comparative Anatomical Study of Organogenesis in Cultured Tissues of Maize, Wheat and Oats 总被引:2,自引:0,他引:2
Five cereals and two related grasses were tested for adventitious shoot production from tissue cultures using methods concordant with those reported to be successful for cereals. The five cereals I wheat (Triticum aestivum L.), oats (Avena sativa L.), and maize (Zea mays L.) Pioneer hybrid 3369A, the Bolivian race Pororo and the Equadorian race Chococenõl were all found to proliferate in culture through an aberrant root-like mechanism of growth which had the external appearance of callus. Two related species, teosinte (Zea mexicana Reeves and Mangelsdorf) and tripsacum (Tripsacum dactyloides L.), were less successful in culture, but grew in the same way. Oats, and probably Pororo and Chococeño, initiated presumptive shoot meristems directly from root vascular tissues within this root-like growth. Hybrid maize and wheat initiated no shoot meristems and produced only roots. The occasional shoot production observed in wheat was discounted as simple carryover of existing shoot apices from the primary embryo cultures. This study suggests that the incidence of shoot regeneration in cultures of these cereals may be related more directly to adventitious bud formation on roots than to any controlled de novo organogenesis from undifferentiated callus. 相似文献
11.
《Plant science》1987,52(3):237-242
Direct propagation of Lycopersicon esculentum Mill. and L. peruvianum (L.) Mill. has been achieved from both reproductive and embryonic stages of the life cycle. Multiple adventitious shoots were induced from immature flower buds on Murashige and Skong (MS) basal medium supplemented with 2 mg 1−1 6-benzylaminopurine (BAP). Multiple shoots and somatic embryos were induced from immature zygotic embryos on HLH basal medium supplemented with 1 g 1−1 yeast extract and 2 mg 1−1 BAP. The nature of the response was related to the developmental stage of the parent embryo at explanting. The process of multiple shoot induction from embryos shows features in common with direct somatic embryogenesis from sexual embryos of Lycopersicon and other genera. 相似文献
12.
Lin Qi Xiaoliang Qin Feng-Min Li Kadambot H.M. Siddique Helmut Brandl Jinzhang Xu 《International journal of phytoremediation》2015,17(3):264-271
The main objective of this study was to investigate the accumulation and distribution of strontium (Sr) in 26 cultivars of wheat (Triticum aestivum L.), husk oat (Avena sativa L) and naked oat (Avena nuda), and barley (Hordeum vulgare L.) for their potential use in phytoremediation.Sr levels had no effect on the accumulation of shoot biomass at tillering or at maturity. Mean shoot Sr concentration of naked oat and barley at tillering was significantly (P < 0.05) higher than that of wheat; Neimengkeyimai-1, a naked oat cultivar, had the highest Sr concentrations. At maturity, of four naked oat cultivars, Neimengkeyimai-1 had the highest Sr content at all measured Sr levels. Leaves had the highest Sr concentrations, followed by roots and straw, and then grain with the lowest. Mean enrichment coefficients from soil to shoots ranged from 0.521 to 1.343; the percentage of stable Sr removed from the soil to the shoots at harvest time was more than 1.4% after 120 days. Neimengkeyimai-1 could be used as a model for further research to find more effective cultivars; and naked oat plants could be selected for phytoremediation to clean up contaminated soil. 相似文献
13.
Norhayati Daud Ahmad Faizal Danny Geelen 《In vitro cellular & developmental biology. Plant》2013,49(2):183-190
An efficient root induction system has been established for in vitro-regenerated Jatropha curcas L. shoots. Callus formation on shoots transferred to auxin containing medium was found to be a prominent and recurrent problem for rooting of in vitro-cultivated J. curcas. In particular, the type of auxins and cytokinins applied in the culture media were shown to strongly influence the severity of callus formation. Shoots cultivated on meta-methoxytopolin riboside (MemTR) were free of callus and produced elongated stems and well-developed leaves in comparison to the cytokinins benzyl adenine, zeatin, and thidiazuron. Subsequent root induction experiments were performed with shoots precultured on MemTR-containing medium. Shoots were excised and transferred to Murashige and Skoog (MS) medium supplemented with different concentrations of indole-3-butyric acid (IBA), indole-3-acetic acid (IAA), and α-naphtaleneacetic acid (NAA). The induction of excessive callus formation was avoided only on IBA-containing medium. The optimum rooting medium with good root induction (35%) and 1.2 roots per shoot contained half-strength MS salts supplemented with 2.5 μM IBA. The same medium supplemented with 0.25% (w/v) activated charcoal produced 46% rooted shoots. Further improvement of rooting was obtained by transferring in vitro grown shoots to woody plant medium containing phloroglucinol (PG). In the presence of 2.5 μM IBA and 238 μM PG, 83% of the shoots rooted with on average 3.1 roots per shoot. We also analyzed the impact of light quality on the rooting capacity of Jatropha in vitro grown shoots. In general, light-emitting diodes (LEDs) light sources were less efficient for root induction. Red LED light provided the most favorable growth conditions, inducing a rooting response in 65% of the shoots, which produced on average 5.5 roots per shoot. These results indicate that adventitious rooting in J. curcas is under control of photoreceptors and that optimal rooting requires fine-tuning of the salt concentration, auxin, and cytokinin balance and application of synergistic compounds. 相似文献
14.
P. Jha C. B. Yadav V. Anjaiah V. Bhat 《In vitro cellular & developmental biology. Plant》2009,45(2):145-154
An efficient in vitro plant regeneration protocol through somatic embryogenesis and direct shoot organogenesis has been developed for pearl millet
(Pennisetum glaucum). Efficient plant regeneration is a prerequisite for a complete genetic transformation protocol. Shoot tips, immature inflorescences,
and seeds of two genotypes (843B and 7042-DMR) of pearl millet formed callus when cultured on Murashige and Skoog (MS) medium
supplemented with varying levels of 2,4-dichlorophenoxyacetic acid (2,4-D; 4.5, 9, 13.5, and 18 μM). The level of 2,4-D, the
type of explant, and the genotype significantly effected callus induction. Calli from each of the three explant types developed
somatic embryos on MS medium containing 2.22 μM 6-benzyladenine (BA) and either 1.13, 2.25, or 4.5 μM of 2,4-D. Somatic embryos
developed from all three explants and generated shoots on MS medium containing high levels of BA (4.4, 8.8, or 13.2 μM) combined
with 0.56 μM 2,4-D. The calli from the immature inflorescences exhibited the highest percentage of somatic embryogenesis and
shoot regeneration. Moreover, these calli yielded the maximum number of differentiated shoots per callus. An efficient and
direct shoot organogenesis protocol, without a visible, intervening callus stage, was successfully developed from shoot tip
explants of both genotypes of pearl millet. Multiple shoots were induced on MS medium containing either BA or kinetin (4.4,
8.8, 17.6, or 26.4 μM). The number of shoots formed per shoot tip was significantly influenced by the level of cytokinin (BA/kinetin)
and genotype. Maximum rooting was induced in 1/2 strength MS with 0.8% activated charcoal. The regenerated plants were transferred
to soil in pots, where they exhibited normal growth. 相似文献
15.
Embryogenic cultures of lucerne (Medicago sativa L.) cv. Robothave been established and propagated on medium containing yeastextract. These cultures consisted of unorganized callus tissuebearing embryogenic centres which increased in size during subculture,yielding new regenerated somatic embryos at the end of each20-d subculture. A development in the propagation of the embryogenic cultureswas the establishment of single embryo culture in hormone-freemedium where, in selected cases, the process of recurrent somaticembryogenesis (RSE) took place on the hypocotyl of explantedembryos. The process was independent of supporting callus tissueand occurred on simple defined medium. Single embryos underwenteither plantlet development or continued RSE on the hypocotyl.One third of the regenerated plantlets showed RSE after thetwo to three trifoliate leaf stage. In these cases shoot developmentstopped and only somatic embryo production took place. In vitrocloning of regenerated plantlets allowed us to reproduce eachparticular genotype before transplantation into soil. Lucerne (alfalfa), Medicago sativa L., somatic embryogenesis, single embryo culture 相似文献
16.
Leaf, cotyledon, and hypocotyl explants were obtained from 3-week-old seedlings of open-pollinated ‘Golden Delicious’ (Malus domestica bork H.) grown in vitro. They were placed on modified Murashige and Skoog (MS) medium containing B5 vitamins, sucrose and agar, supplemented with 6-benzylaminopurine (BAP) and α-naphthaleneacetic acid (NAA), and maintained at 25°C±2 in the light or in the dark to assess morphogenetic responses. Leaf and cotyledon explants cultured in the dark for an initial 3 weeks, then transferred to light for 4 weeks, produced 5- to 20-fold more adventitious shoots than those cultured for 7 weeks in the light. Conversely, light did not significantly influence the number of adventitious shoots formed on hypocotyl explants. Five-minute daily exposures of leaf explants to red light (651 nm) suppressed adventitious shoot formation by 80%; five-minute exposure to far-red light (729 nm) immediately following the red light counteracted the red suppression. Seedling explants, immature fruit halves and immature embryos were also cultured on Schenk and Hildebrandt (SH) medium containing 2, 4-dichlorophenoxyacetic acid (2, 4-D), p-chlorophenoxyacetic acid (CPA) and kinetin. Light inhibited callus formation on leaf and cotyledon explants, but not on hypocotyl explants. The derived callus was placed on MS + BAP or MS + BAP + NAA for shoot regeneration. Both shoots and roots regenerated from callus placed in the dark but not in the light; the frequency of shoot regeneration was 5% or less. Regenerated shoots were rooted on MS macronutrient salts (1/3 concentration), micronutrients, i-inositol, thiamine HCl, sucrose and agar with or without indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), or NAA under a light intensity of 5.0 W.m-2 (16 h per day). Auxin concentration strongly influenced root morphology. 相似文献
17.
In vitro variation of B chromosomes was studied by examining the callus cells derived from the immature embryos from a cross of Chinese Spring wheat ( Triticum aestivum L.) and Fin 7416 rye ( Secale cereale L.) carrying two B chromosomes. In 40-d-old callus cells, the numbers of B chromosomes ranged from one to four in 65.6% of the cells observed. The distribution of B chromosome numbers was associated with the ploidy levels of the normal chromosomes (A chromosomes). The frequency of the cells with high numbers of B chromosomes (i.e., three or four B chromosomes) in the amphiploid cells with 56 A chromosomes was greater than those in the haploid cells with 28 A chromosomes. Although structural changes in the rye A chromosomes were observed, cytological observation and genomic in situ hybridization demonstrated that the rye B chromosomes were conserved in morphological appearance following tissue culture. 相似文献
18.
L. M. R. Rinaldi 《In vitro cellular & developmental biology. Plant》1999,35(1):25-28
Summary Adventitious shoot induction from zygotic embryo and seedling explants of Cycas revoluta was studied, with reference to both nitrogen formulation of the medium and light. The presence of nitrate as a sole source
of nitrogen in Klimaszewska and Keller (KK) medium did not promote shoot induction; on the other hand, shoot induction was
promoted by the use of ammonium-containing media, i.e., Schenk and Hildebrandt (SH) and Murashige and Skoog (MS). In the case
of zygotic embryos, the percentage of responding explants and the number of regenerated shoots were significantly higher on
SH medium than on MS medium. With seedling explants, shoot induction was not affected by the use of SH medium versus MS medium.
Photoperiod also influenced bud formation and development. The absence of light during shoot induction stimulated callus formation
and very few differentiated shoots. Shoot induction from zygotic embryos was positively affected by the application of 4-
and 8-wk photoperiod exposures, the combination SH medium/8-wk photoperiod exposure giving the best results in terms of shoot
induction and development. Rooting of shoots was improved by their culture in medium containing NAA. 相似文献
19.
Dark pretreatment improves adventitious shoot organogenesis from cotyledons of diploid watermelon 总被引:6,自引:0,他引:6
The influence of light incubation during embryo germination on shoot organogenesis from cotyledons of four diploid watermelon
[Citrullus lanatus (Thumb.) Matsum. & Nakai cultivars was examined. Germinating embryos in darkness significantly improved the number of explants
that produced harvestable shoots during the 6 week incubation period on shoot regeneration medium under a 16-h photoperiod.
The percentage of explants with shoots more than doubled for `Crimson Sweet' and was about 1.5-fold greater for `Sweet Gem'
and `Yellow Doll' when embryos were germinated in darkness. The percentage of explants with shoots was not significantly improved
for `Minilee' by pretreating seedlings in darkness. This study demonstrates that optimal shoot regeneration can be obtained
by germinating embryos in darkness before preparing cotyledon explants.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
20.
The effect of phosphate starvation on growth and acid phosphatases (APases) localization and activity in oat tissues was investigated. Oat cultivars (Avena sativa L.??Arab, Polar, Szakal) were grown for 1?C3?weeks in complete nutrient medium (+P) and without phosphate (?P). Pi concentration in plant tissues decreased strongly after culturing on ?P medium. Pi deficit reduced shoot growth, stimulated root elongation and increased ratio of root/shoot in all oat cultivars. Pi deficit had a greater impact on growth of oat cv. Polar than other varieties. A decrease in the internal Pi status led to an increase of acid phosphatase activities in extracts from shoots and roots, and in root exudates. The highest activity of secreted APases was observed for oat cv. Arab, during the third week of growth under Pi-deficient conditions. The activity of extracellular APase was high in young, growing zones of roots of ?P plants. Histochemical visualization indicated high activity of APases in the epidermis and vascular tissues of ?P plants. Pi deficiency increased intracellular APase activity in shoot mainly in oat cv. Polar, whereas APase activity in roots was the highest in oat cv. Szakal. Protein extracts from roots and shoots were run on native discontinuous PAGE to determine which isoform(s) may be affected by Pi deficiency. Three major APase isoforms were detected in all oat plants; one was strongly induced by Pi deficit. The studied oat cultivars differed in terms of acclimation to deficiency of phosphate??used various pools of APases to acquire Pi from external or internal sources. 相似文献