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1.
We examined the elongation rate, water status and solute accumulation in the seminal roots of wheat seedlings (Triticum aestivum L.) that were growing in vermiculite with a water potential (Ψw) ranging from −0 03 to −1 10 MPa. The elongation rate of the primary seminal root was similar to that of the first pair of
seminal roots but that of the second pair of seminal roots was lower at all values of Ψw tested. The elongation rate was highest in vermiculite with a Ψw of −0.03 MPa but did not decrease significantly until the Ψw was reduced to −0.15 MPa. Further reductions in Ψw reduced the elongation rate markedly. The Ψw of mature tissues was always similar to that of vermiculite. The osmotic potential (Ψo) decreased to the same extent as the decrease in Ψw. Thus, the turgor pressure (Ψp) remained unchanged even in vermiculite with a low Ψw. In elongating tissues, Ψw and Ψo were far lower than they were in mature tissues and, thus, reductions in turgor were not significant. Even when the Ψw of vermiculite changed, there were no consistent changes in terms of a difference in Ψw between elongating plus mature tissues and vermiculite. There were also no consistent changes in levels of osmotica, calculated
using the van’t Hoff’s law, in the elongating tissues but the levels in mature tissues increased in vermiculite with a low
Ψw. Our results suggest that (1) reductions in root elongation in vermiculite with a low Ψw were caused by reductions in the extensibility and/or increases in the yield threshold of cell walls and by reductions in
the hydraulic conductivity of the tissues; and (2) a seminal root regulates its growth to keep turgor pressure unchanged. 相似文献
2.
One-month old calli of two indica rice genotypes, i.e., Basmati-370 and Basmati-Kashmir were subjected to two iso-osmotic
concentrations (−0.57 MPa and −0.74 MPa) created with 50 and 100 mol m−3 NaCl or 10 and 18% solutions of PEG-8000. Both genotypes tolerated only low levels of stress and showed severe growth suppression
at −0.74 MPa. The degree of stress tolerance of both genotypes was greater for PEG induced stress than for NaCl induced stress.
The relative growth rate of callus was reduced under both stresses, however, the reverse was true for callus dry weight. Sodium
(Na+) content of the callus tissue was increased only under NaCl induced stress. Salt induced stress reduced K+ and Ca2+ contents, but the PEG induced stress increased them. Higher levels of stress increased the proline content many folds with
more increase being under PEG stress than that under NaCl. Water and osmotic potentials of the callus tissue decreased, whereas
turgor potential increased under both abiotic stresses. Overall, Basmati-370 was more tolerant to both NaCl and PEG induced
stresses than Basmati-Kashmir, because of less reduction in growth and more dry weight. Moreover, Basmati-370 accumulated
higher amounts of cations, free proline, and maintained maximum turgor as compared to Basmati-Kashmir. In conclusion, at cellular
level, mechanism of NaCl induced osmotic stress tolerance was found to be associated with more ionic accumulation of inorganic
solutes and that of PEG induced osmotic stress tolerance with the accumulation of free proline, as an important osmolyte in
the cytosol. 相似文献
3.
Inhibition of photosynthetic processes in foliose lichens induced by temperature and osmotic stress 总被引:2,自引:0,他引:2
Negative effects of osmotically-induced dehydration of two foliose lichen species, Lasallia pustulata and Umbilicaria hirsuta, was studied at physiological (22 °C), low (5 °C) and freezing temperature (−10 °C), using chlorophyll (Chl) fluorescence.
In both species, exposure to increasing sucrose concentrations led to a pronounced decrease in potential (FV/FM), and actual (Φ2) quantum yields of photochemical processes in photosystem 2. L. pustulata was more sensitive to osmotic stress, because comparable osmotic dehydration inhibited FV/FM and Φ2 more than in U. hirsuta. Critical concentration of sucrose that fully inhibited photochemical processes of photosynthesis was 2.5 M, which represented
water potential (Ψw) of −18.8 MPa. Decrease in background Chl fluorescence (F0) and increase in non-photochemical quenching (qN) revealed two phases of osmotic stress in lichens: phase I with no change
(Ψw 0 to −6.6 MPa) and phase II (Ψw −11.3 to −18.8 MPa) typical by substantial change in Chl fluorescence parameters. Effects of thallus anatomy on species-specific
response to osmotic dehydration is discussed and attributed to the results obtained by optical microscopy and Chl fluorescence
imaging technique. 相似文献
4.
Plantlet regeneration through shoot formation from young leaf explant-derived callus of Camptotheca acuminata is described. Calli were obtained by placing leaf explants on Woody plant medium (WPM) supplemented with various concentrations
of 6-benzyladenine (BA) and naphthaleneacetic acid (NAA) or 2,4-dichlorophenoxyacetic acid (2,4-D). Callus induction was observed
in all media evaluated. On the shoot induction medium, the callus induced on the WPM medium containing 19.8 μM BA and 5.8
μM NAA was the most effective, providing high shoot regeneration frequency (70.3 %) as well as the highest number of shoots
(11.2 shoots explant−1). The good rooting percentage and root quality (98 %, 5.9 roots shoot−1) were achieved on WPM medium supplemented with 9.6 μM indole-3-butyric acid (IBA). 96 % of the in vitro rooted plantlets with well developed shoots and roots survived transfer to soil. 相似文献
5.
In sunflower (Helianthus annuus L.) grown under controlled conditions and subjected to drought by withholding watering, net photosynthetic rate (P
N) and stomatal conductance (g
s) of attached leaves decreased as leaf water potential (Ψw) declined from −0.3 to −2.9 MPa. Although g
s decreased over the whole range of Ψw, nearly constant values in the intercellular CO2 concentrations (C
i) were observed as Ψw decreased to −1.8 MPa, but C
i increased as Ψw decreased further. Relative quantum yield, photochemical quenching, and the apparent quantum yield of photosynthesis decreased
with water deficit, whereas non-photochemical quenching (qNP) increased progressively. A highly significant negative relationship between qNP and ATP content was observed. Water deficit did not alter the pyridine nucleotide concentration but decreased ATP content
suggesting metabolic impairment. At a photon flux density of 550 μmol m−2 s−1, the allocation of electrons from photosystem (PS) 2 to O2 reduction was increased by 51 %, while the allocation to CO2 assimilation was diminished by 32 %, as Ψw declined from −0.3 to −2.9 MPa. A significant linear relationship between mean P
N and the rate of total linear electron transport was observed in well watered plants, the correlation becoming curvilinear
when water deficit increased. The maximum quantum yield of PS2 was not affected by water deficit, whereas qP declined only at very severe stress and the excess photon energy was dissipated by increasing qNP indicating that a greater proportion of the energy was thermally dissipated. This accounted for the apparent down-regulation
of PS2 and supported the protective role of qNP against photoinhibition in sunflower. 相似文献
6.
M. Ashraf 《Plant and Soil》1989,119(2):205-210
The physiological basis of salt tolerance of two cultivars of blackgram, cv Candhari Mash (relatively salt tolerant) and cv
Mash 654 (salt sensitive), was assessed in salinized sand culture at the flowering stage. Increasing NaCl concentration in
the rooting medium significantly reduced the chlorophyll a, chlorophyll b, and total chlorophyll, leaf water potential (Ψw), leaf solute potential (Ψs), and leaf turgor potential (Ψp) in both the cultivars. Leaf protein and proline content was increased as a result of increasing salt concentration in both
cultivars. High salt concentrations had no significant effect on the seed protein content of both cultivars. At high salinities,
cv Candhari Mash had significantly greater chlorophyll a, chlorophyll b and total chlorophyll, leaf water potential, solute
potential, and turgor potential than cv Mash 654, but the latter had greater leaf proline content than cv Candhari Mash. Cultivars
did not differ significantly for both leaf and seed protein contents.
The relatively salt tolerant cv Candhari Mash maintained high leaf water potential and turgor potential to resist salt injury.
Leaf proline content had negative correlation with salt tolerance in blackgram. 相似文献
7.
Organogenic cultures were induced from zygotic embryo and megagametophyte explants of the Central American cycad species,
Dioon edule. Plant growth medium consisted of B5 major salts, Murashige and Skoog minor salts and organics, 400 mg l−1 glutamine, 100 mg l−1 arginine, 100 mg l−1 asparagine, 60 g l−1 sucrose, 8 g l−1 Difco Bacto agar and was supplemented with kinetin (0 – 13.94 μM) and 2,4-dichlorophenoxyacetic acid (2,4-D) (0 – 9.05 μM)
arranged as a 5×4 factorial in a randomized block design. Callus initiation occurred on a wide range of medium formulations
from megagametophyte explants; however, shoot formation occurred only on medium supplemented with 2.26 μM 2,4-D. In comparison,
callus initiation from explanted zygotic embryos occurred on fewer medium formulations, and adventitious shoot induction occurred
from callus on formulations with 9.29–13.94 μM kinetin + 0.45–9.05 μM 2,4-D. Rooted shoots, derived from megagametophyte and
zygotic embryo cultures, have been regenerated.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
8.
Screening for drought tolerance in Sorghum using cell culture 总被引:4,自引:0,他引:4
R. H. Smith S. Bhaskaran F. R. Miller 《In vitro cellular & developmental biology. Plant》1985,21(10):541-545
Summary Callus growth from 10 cultivars ofSorghum bicolor (L.) Moench was measured with increasing levels of polyethylene glycol (PEG) as an osmoticum in the medium to determine whether
differences among these cultivars at the cellular level in response to osmotic stress existed. These cellular ratings were
compared to field ratings from the 10 tolerant-to-susceptible cultivars when grown under drought conditions to determine whether
cellular ratings corresponded to differences in drought tolerance at the plant level. Callus cultures were grown on Murashige
and Skoog inorganic salt formulation plus vitamins, 2,4-dichlorophenoxyacetic acid (2,4-D), kinetin and sucrose, supplemented
with 0 to 25% (wt/vol) PEG corresponding to −0.2 to −1.62 MPa osmotic potential. Results suggest that PEG-induced osmotic
stress on callus cultures can be used to screen sorghum cultivars for potential early field (preflowering) drought tolerance.
This implies that at least a component of the early field drought tolerance in sorghum may have a cellular basis.
This study was supported by U.S. Agency for International Development Grant AID/DSAN/XII/G-0149, and USDA Competitive Grants
Program. 相似文献
9.
Sandra J. Bucci Fabian G. Scholz Guillermo Goldstein Frederick C. Meinzer Maria E. Arce 《Oecologia》2009,160(4):631-641
Adaptations of species to capture limiting resources is central for understanding structure and function of ecosystems. We
studied the water economy of nine woody species differing in rooting depth in a Patagonian shrub steppe from southern Argentina
to understand how soil water availability and rooting depth determine their hydraulic architecture. Soil water content and
potentials, leaf water potentials (ΨLeaf), hydraulic conductivity, wood density (ρw), rooting depth, and specific leaf area (SLA) were measured during two summers. Water potentials in the upper soil layers
during a summer drought ranged from −2.3 to −3.6 MPa, increasing to −0.05 MPa below 150 cm. Predawn ΨLeaf was used as a surrogate of weighted mean soil water potential because no statistical differences in ΨLeaf were observed between exposed and covered leaves. Species-specific differences in predawn ΨLeaf were consistent with rooting depths. Predawn ΨLeaf ranged from −4.0 MPa for shallow rooted shrubs to −1.0 MPa for deep-rooted shrubs, suggesting that the roots of the latter
have access to abundant moisture, whereas shallow-rooted shrubs are adapted to use water deposited mainly by small rainfall
events. Wood density was a good predictor of hydraulic conductivity and SLA. Overall, we found that shallow rooted species
had efficient water transport in terms of high specific and leaf specific hydraulic conductivity, low ρw, high SLA and a low minimum ΨLeaf that exhibited strong seasonal changes, whereas deeply rooted shrubs maintained similar minimum ΨLeaf throughout the year, had stems with high ρw and low hydraulic conductivity and leaves with low SLA. These two hydraulic syndromes were the extremes of a continuum with
several species occupying different portions of a gradient in hydraulic characteristics. It appears that the marginal cost
of having an extensive root system (e.g., high ρw and root hydraulic resistance) contributes to low growth rates of the deeply rooted species. 相似文献
10.
Jameel M. Al-Khayri Christine E. Shamblin Edwin J. Anderson 《In vitro cellular & developmental biology. Plant》1996,32(4):227-232
Summary This study was conducted to establish and optimize a regeneration system for adapted U.S. rice genotypes including three commercial
rice cultivars (LaGrue, Katy, and Alan) and two Arkansas breeding lines. Factors evaluated in the study were genotype, sugar
type, and phytohormone concentration. The system consisted of two phases, callus induction and plant regeneration. In the
callus induction phase, mature caryopses were cultured on MS medium containing either 1% sucrose combined with 3% sorbitol
or 4% sucrose alone, and 0.5 to 4 mg·L−1 (2.26 to 18.10 μM) 2,4-D with or without 0.5mg·L−1) (2.32 μM) kinetin. In the plant regeneration phase, callus was transferred to 2,4-D-free MS medium containing 0 or 2 mg·L−1 (9.29 μM) kinetin combined with 0 or 0.1 mg·L−1 (0.54 μM) NAA. Callus induction commenced within a week, independent of the treatments. Callus growth and plant regeneration, however,
were significantly influenced by interactions among experimental factors. Generally, the greatest callus growth and plant
regeneration were obtained with 0.5 mg·L−1 (2.26 μM) 2,4-D and decreased with increasing 2,4-D concentrations. Kinetin enhanced callus growth only when combined with 0.5 mg·L−1 (2.26 μM) 2,4-D, and 4% sucrose. Inducing callus on kinetin-containing medium generally enhanced regeneration capacity in the presence
of sucrose but not with a sucrose/sorbitol combination. Media containing sucrose alone generally supported more callus proliferation,
but the sucrose/sorbitol combination improved regeneration of some cultivars. NAA and kinetin had little effect on regeneration. 相似文献
11.
Quillaguamán J Doan-Van T Guzmán H Guzmán D Martín J Everest A Hatti-Kaul R 《Applied microbiology and biotechnology》2008,78(2):227-232
High poly(3-hydroxybutyrate) (PHB) content and volumetric productivity were achieved by fed-batch culture of Halomonas boliviensis using a defined medium. Initial shake flask cultivations in a minimal medium revealed that the growth of H. boliviensis was supported only when the medium was supplemented with aspartic acid, glycine, or glutamine. Addition of 0.1% (w/v) glutamine in the medium resulted in the highest cell dry weight (CDW; 3.9 g l−1). Glutamine was replaced by the less expensive monosodium glutamate (MSG) in the medium without any notable change in the
final cell density. Effect of initial concentrations of NH4Cl and K2HPO4 on cell growth and PHB accumulation by H. boliviensis was then analyzed using a fed-batch fermentation system. The best conditions for PHB production by H. boliviensis were attained using 0.4% (w/v) NH4Cl and 0.22% (w/v) K2HPO4 and adding MSG intermittently to the fermentor. Poly(3-hydroxybutyrate) content and CDW reached 90 wt.% and 23 g l−1, respectively, after 18 h of cultivation. In order to increase CDW and PHB content, MSG, NH4Cl, and K2HPO4 were initially fed to the fermentor to maintain their concentrations at 2%, 0.4%, and 0.22% (w/v), respectively, and subsequently their feed was suppressed. This resulted in a CDW of 44 g l−1, PHB content of 81 wt.%, and PHB volumetric productivity of 1.1 g l−1 h−1. 相似文献
12.
Yuexia Wang Bridget A. Ruemmele Joel M. Chandlee W. Michael Sullivan Jane E. Knapp Albert P. Kausch 《In vitro cellular & developmental biology. Plant》2002,38(5):460-467
Summary Embryogenic callus induction and plant regeneration systems have long been established for creeping bentgrass (Agrostis palustris Huds.), but little research has been reported on optimal medium for embryogenic callus induction and plant regeneration in
velvet bentgrass (Agrostis canina L.), colonial bentgrass (Agrostis capillaries L.), and annual bluegrass (Poa annua L.). The present study compared 14 callus induction media and eight regeneration media for their efficacies on embryogenic
callus induction and plant regeneration in these four species. The embryogenic callus initiation media contained the Murashige
and Skoog inorganic salts and vitamins supplemented with 2,4-dichlorophenoxyacetic acid or 3,6-dichloro-anisic acid and 6-benzyladenine.
l-Proline or casein hydrolyzate was included in some media to stimulate embryogenic callus formation and plant regeneration.
The frequencies of embryogenic callus formation ranged from 0% to 38% and exhibited medium differences within each of the
four species. Callus induction media, plant regeneration media, and genotypes affected plant regeneration rates, which varied
between 0% and 100%. The embryogenic callus induced on Murashige and Skoog medium supplemented with 500 mgl−1 casein hydrolyzate, 6.63 mg l−1 (30 μM) 3,6-dichloro-anisic acid and 0.5–2.0 mg l−1 (2–9 μM) 6-benzyladenine had much higher regeneration rates than those formed on other callus induction media. Embryogenic callus
of annual bluegrass had higher regeneration rates than those of bentgrass species. MSA2D, a media containing 2 mgl−1 (8 μM) 2,4-dichlorophenoxyacetic acid, 100 mgl−1
myo-inositol, and 150 mgl−1 asparagine, was effective in promoting embryogenic callus formation in creeping bentgrass but not in colonial and velvet
bentgrasses and annual bluegrass. 相似文献
13.
Heung Kyu Moon So Young Park Yong Wook Kim Sea Hyun Kim 《In vitro cellular & developmental biology. Plant》2008,44(2):119-127
An effective micropropagation technique via somatic embryogenesis has been developed using tissue from serially grafted shoots
generated from a mature Kalopanax septemlobus tree (~40 y old). Callus was induced from leaf segments obtained from the grafts by culturing the explants in Murashige and
Skoog (MS) medium supplemented with 2,4-D and 3% w/v sucrose under darkness. The effects of sucrose, coconut water, and polyethylene glycol (PEG-3350) were evaluated as factors
to promote development of somatic embryos (SEs) from embryogenic callus. More than 90% of explants formed callus; however,
only 2.5%, or 20 leaf segments out of 800 explants, formed embryogenic callus after 8 wk of culture. High sucrose concentrations
(3% and 5% w/v) were effective in inducing SEs. Treatment with 2–10% v/v coconut water also had a positive effect on embryo induction. A synergistic effect on SE induction was obtained using sucrose
and PEG, with presence of the latter compound resulting in smaller, more uniform SEs. Embryo germination and conversion to
plantlets were significantly influenced by the gelling agents. In general, gelrite-gelled medium was superior to agar-gelled
medium. In gelrite-gelled medium, gibberillic acid (GA3) enhanced embryo germination. Converted plantlets in an artificial soil mixture showed a 91% survival rate and displayed
no distinct morphological variations. Our results indicate that reliable somatic embryogenesis and plant production can be
achieved with rejuvenated tissues after repeated grafting of shoots derived from a mature Kalopanax septemlobus tree. 相似文献
14.
Summary Callus induction and later plant regeneration were studied in four widely grown garlic (Allium sativum L.) cultivars from Europe. Root segments from in vitro plantlets were used as starting material. In addition to cultivar effects, the effects of auxin and cytokinin levels and
the position of the segments on the root were studied. There were no statistically significant differences among cultivars
for the number of root segments that induced callus in the two series of experiments. The average induction frequency was
34.7% in the first series of experiments. Callus induction on apical root segments was significantly higher compared to callus
induction on non-apical root segments in the second series of experiments. Two months after callus induction, callus lines
were transferred to a regeneration medium consisting of Murashige and Skoog basal medium supplemented with 30gl−1 sucrose and 1 mgl−1 (4.6μM) kinetin. Calluses derived from different experiments were quite uniform with respect to their regeneration potential. Also
it was found that our regeneration system was cultivar-independent. The average shoot regeneration frequency was 17.9% in
the first series of experiments. Highly significant differences were found in the frequency of shoot regeneration among different
callus induction treatments. When the cytokinin 6-(γ,γ-dimethylallylamino)purine (0.1mgl−1∶0.5 μM) was present during callus induction, shoot regeneration ranged from 30.10 to 47.60%. Shoot regeneration from callus induced
on non-apical segments was higher, although not significant, compared to callus induction from apical root segments in the
second series of experiments. All in all, an efficient callus induction and plant regeneration system was developed from both
apical and non-apical segments taken along the entire length of the roots. This system has potential to be used for garlic
transformation. 相似文献
15.
In Vitis vinifera L. berries, the onset of ripening (known as “veraison”) involves loss of turgor (P) in the mesocarp cells. We hypothesized
that P loss was associated with an accumulation of apoplastic solutes in mesocarp tissue prior to veraison. Apoplastic sap
was extracted from the mesocarp by centrifugation at the appropriate gravity to measure the apoplast solute potential (ΨsA) and assay the sap composition. The ΨsA was about −0.2 MPa early in development, decreased about 1.0 MPa by veraison, and continued to decrease during ripening to
almost −4.0 MPa by the end of berry development. Potassium, malate, tartrate, proline, glucose, fructose, and sucrose were
quantified in apoplastic sap. The calculated contribution of these solutes was about 50% of the total ΨsA preveraison, but increased to about 75% as fructose and glucose accumulated during ripening. The contribution of the estimated
matric potential to apoplast water potential decreased during development and was only 1.5% postveraison. We conclude that
high concentrations of solutes accumulated in the mesocarp apoplast prior to veraison, and that P loss was a direct result
of decreased ΨsA. Because ΨsA decreased before veraison, our findings suggest that apoplast solutes play an important role in the events of cellular metabolism
that lead to the onset of ripening. 相似文献
16.
Federico A. Gutiérrez-Miceli Lourdes Arias Nicolás Juarez-Rodríguez Miguel Abud-Archila Aldo Amaro-Reyes Luc Dendooven 《In vitro cellular & developmental biology. Plant》2010,46(1):57-63
This paper reports on the optimum concentrations of naphthalene acetic acid (NAA) and 6-benzyladenine (BA) to stimulate callus
growth and NAA; kinetin and silver nitrate (AgNO3) for callus redifferentiation in Dianthus caryophyllus L. Meristems were excised and placed in MS medium with 30 g l−1 sucrose and 9.0 μM 2,4-d. Callus clusters were transferred to MS medium containing NAA (0, 1.7, 3.3, and 5.0 μM) and BA (0, 1.7, 3.3, and 5.0 μM)
for proliferation and to MS medium with 30 g l−1 sucrose, 2.5 g l−1 phytagel, kinetin (0, 33, and 66 μM); NAA (0, 7.95, and 15.9 μM) and AgNO3 (0, 23.54 and 47.08 μM) for shoot and root induction. Treatments were applied according to a Box–Behnken design. After callus
growth and redifferentiation, plants were incubated in the greenhouse at 18 ± 2°C for 4 wk and at 20–26°C for 4 wk. Finally,
plants were changed to near-commercial greenhouse conditions with different day (30–35°C) and night (16–24°C) temperatures.
Results showed better callus growth at higher NAA concentrations. A maximum callus weight was found with 5.0 μM NAA but without
BA. A maximum of 78% calluses with shoots was obtained with 15.9 μM NAA, 47.08 μM AgNO3, and 0.74 μM kinetin and 58% with roots with 15.7 μM NAA and 47.08 μM AgNO3, but without kinetin. The shoots obtained showed little hyperhydricity. Vigorous plants were obtained after gradual acclimatization
with an 80% survival rate under nursery conditions. 相似文献
17.
Wei Tang Zhongchen Guo Fan Ouyang 《In vitro cellular & developmental biology. Plant》2001,37(5):558-563
Summary Mature zygotic embryos of eight (open-pollinated) families of loblolly pine (Pinus taeda L.) were cultured on eight different basal salt formulations, each supplemented with 36.2 μM 2,4-dichlorophenoxyacetic acid, 17.8 μM 6-benzyladenine, 18.6 μM kinetin, 500 mg l−1 casein hydrolysate, and 500 mg l−1
l-glutamine for 9 wk; embryogenic tissue was formed on cotyledons, hypocotyls, and radieles of mature zygotic embryos. Callus
was subcultured on the callus proliferation medium, the same as the induction medium but with one-fifth concentration of auxin
and cytokinin for 9 wk. On this medium a white to translucent, glossy, mucilaginous embryogenic callus containing embryogenic
suspensor masses (ESMs) was obtained. The highest frequency of explants forming embryogenic tissue, 17%, occurred on a modified
Murashige and Skoog salts basal medium containing the concentration of KNO3, Ca(NO3)2·4H2O, NH4NO3, KCl, ZnSO4·7H2O, and MnSO4·H2O, 720, 1900, 400, 250, 25.8, and 25.35 mg l−1, respectively. Embryogenic suspension cultures were established by culturing embryogenic callus in liquid callus proliferation
medium. Liquid cultures containing ESMs were transferred to medium containing abscisic acid, polyethylene glycols, and activated
charcoal for stimulating the production of cotyledonary somatic embryos. Mature somatic embryos germinated for 4–12 wk on
medium containing indole-butyric acid, gibberellic acid, 6-benzyladenine, activated charcoal, and reduced sucrose concentration
(15 g l−1). Two hundred and ninety-one regenerated plantlets were transferred to a perlite:peatmoss:vermiculite (1∶1∶1) mixture, then
the plants were transplanted to soil in the earth, and 73 plantlets survived in the field. 相似文献
18.
S. A. Webster S. A. Mitchell W. A. Gallimore L. A. D. Williams M. H. Ahmad 《In vitro cellular & developmental biology. Plant》2008,44(2):112-118
A procedure for producing somatic embryos enriched with dibenzyl trisulfide (DTS) using a hormone-dependent culture system
is reported for Petiveria alliacea L. (Guinea hen weed). Leaf explants were cultured on a Murashige and Skoog medium supplemented with a range of naphthaleneacetic
acid (NAA) concentrations and a fixed concentration of benzyladenine (BAP) at 11.0 μM and sucrose or glucose at 30 g l−1. Leaf explants cultured on all media types started to form callus at the cut surfaces of the discs 10–14 d after initiation.
The type of sugar used influenced average fresh weight, the propensity to form roots, as well as the embryogenic response.
The highest mean fresh weight (337.7 ± 26.18 mg) and mean root number (23.7 ± 1.69) was produced on media enriched with sucrose
and supplemented with 53.7 μM NAA and 11.0 μM BAP. An ethanol extract of rhizogenic/embryogenic callus or somatic embryos
was subjected to high-performance liquid chromatography analysis, which revealed the presence of DTS in both extracts. UV
spectral analysis and the use of standard quantitation procedures showed that the quantity of DTS in the somatic embryo extract,
at 0.16% (w/v), was approximately 30-fold higher than in rhizogenic/embryogenic callus (0.0055% w/v) of similar fresh weight. These results indicate that it is possible to biosynthesize approximately 6 mg of natural DTS from
3,808 mg of fresh somatic embryos within 10 wk from less than three leaf explants. 相似文献
19.
Joyeeta Biswas Bikash Chowdhury A. Bhattacharya A. B. Mandal 《In vitro cellular & developmental biology. Plant》2002,38(5):525-530
Summary
In vitro screening at the cellular level was performed with mature seed-derived callus from five rice varieties, viz. IR 18351-229-3,
IR 3185-6-3-3-2, SR 26-B, Nona Bokra, and C 14-8 of diverse geographical origin and with differential drought resistance at
the in planta level. Callus was induced from mature seeds on Murashige and Skoog medium supplemented with 2.0 mgl−1 (9 μM) of 2,4-dichlorophenoxyacetic acid (2,4-D) and 5.0, 10.0, and 15.0 gl−1 of high molecular weight polyethylene glycol (PEG, 6000) as stressing agent to create chemical drought. Simultaneous efforts
were also made to assess the effects of chemical drought in altering morphogenetic response in different varieties under in vitro culture. Seed germination was almost unaffected in SR 26-B and C 14-8, unlike in other varieties where germination was seriously
affected. In general, seed germination was found to be decreased in three genotypes, viz. IR 18351-229-3, IR 3185-6-3-3-2,
and Nona Bokra, with increased PEG concentrations. All genotypes displayed callus induction percentage in decreasing order
with increased PEG concentrations supplemented in the callus induction medium (CIM), except SR 26-B and Nona Bokra. Callus
induction was found to be more on CIM fortified with 5.0 gl−1 PEG. In general, embryogenic callus induction and plantlet regeneration was found to be indirectly proportional to increased
PEG concentrations used in CIM. Considering all characters, C 14-8 was found to be most appropriate in developing drought-tolerant
lines under in vitro culture conditions followed by SR 26-B and Nona Bokra. A number of putative drought-tolerant plants were developed in C 14-8,
SR 26-B, Nona Bokra, and IR 18351-29-3, and forwarded for field evaluation. In the majority of the progenies, a monogenic
inheritance pattern for the drought tolerance character was observed. 相似文献
20.
In a previous study on the effects of N-supply on leaf cell elongation, the spatial distribution of relative cell elongation
rates (RCER), epidermal cell turgor, osmotic pressure (OP) and water potential (Ψ) along the elongation zone of the third
leaf of barley was determined (W. Fricke et al. 1997, Planta 202: 522–530). The results suggested that in plants receiving
N at fixed relative addition rates (N-supply limitation of growth), cell elongation was rate-limited by the rate of solute
provision, whereas in plants growing on complete nutrient solution containing excessive amounts of N (N-demand limitation),
cell elongation was rate-limited by the rate of water supply or wall yielding. In the present paper, these suggestions were
tested further. The generation rates of cell OP, turgor and Ψ along the elongation zone were calculated by applying the continuity
equation of fluid dynamics to the previous data. To allow a more conclusive interpretation of results, anatomical data were
collected and bulk solute concentrations determined. The rate of OP generation generally exceeded the rate of turgor generation.
As a result, negative values of cell Ψ were created, particularly in demand-limited plants. These plants showed highest RCER
along the elongation zone and a Ψ gradient of at least −0.15 MPa between water source (xylem) and expanding epidermal cells.
The latter was similar to a theoretically predicted value (−0.18 MPa). Highest rates of OP generation were observed in demand-limited
plants, with a maximum rate of 0.112 MPa · h−1 at 16–20 mm from the leaf base. This was almost twice the rate in N-supply-limited plants and implied that the cells in the
leaf elongation zone were capable of importing (or synthesising) every minute almost 1 mM of osmolytes. Potassium, Cl− and NO3
− were the main inorganic osmolytes (only determined for demand-limited plants). Their concentrations suggest that, unlike
the situation in fully expanded epidermal cells, sugars are used to generate OP and turgor. Anatomical data revealed that
the zone of lateral cell expansion extended distally beyond the zone of cell elongation. It is concluded that leaf cell expansion
in barley relies on high rates of water and solute supply, rates that may not be sustainable during periods of sufficient
N-supply (limitation by water supply: Ψ gradients) or limiting N-supply (limitation by solute provision: reduced OP-generation
rates). To minimise the possibility of growth limitation by water and osmolyte provision, longitudinal and lateral cell expansion
peak at different locations along the growth zone.
Received: 15 October 1997 / Accepted: 12 March 1998 相似文献