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1.
Earlier, we reported that mutation in the Male Sterile33 (MS33) locus in Arabidopsis thaliana causes inhibition of stamen filament growth and a defect in the maturation of pollen grains [Fei and Sawhney (1999) Physiol Plant 105:165–170; Fei and Sawhney (2001) Can J Bot 79:118–129]. Here we report that the ms33 mutant has other pleiotropic effects, including aberrant growth of all floral organs and a delay in seed germination and in flowering time. These defects could be partially or completely restored by low temperature or by exogenous gibberellin A4 (GA4), which in all cases was more effective than GA3 Analysis of endogenous GAs showed that in wild type (WT) mature flowers GA4 was the major GA, and that relative to WT the ms33
flowers had low levels of the growth active GAs, GA1 and GA4, and very reduced levels of GA9, GA24 and GA15, precursors of GA4. This suggests that mutation in the MS33 gene may suppress the GA biosynthetic pathway that leads to GA4
via GA9 and the early 13-H C20
GAs. WT flowers also possessed a much higher level of indole-3-acetic acid (IAA), and a lower level of abscisic acid (ABA), relative to ms33 flowers. Low temperature induced partial restoration of male fertility in the ms33
flowers and this was associated with partial increase in GA4. In contrast, in WT flowers GA1 and GA4 were very much reduced by low temperature. Low temperature also had little effect on IAA or ABA levels of ms33 flowers, but did reduce (>2-fold) IAA levels in WT flowers. The double mutants, ms33 aba1-1 (an ABA-deficient mutant), and ms33 spy-3 (a GA signal transduction mutant) had flower phenotypes similar to ms33. Together, the data suggest that the developmental defects in the
ms33 mutant are unrelated to ABA levels, but may be causally associated with reduced levels of IAA, GA1 and GA4, compared to WT flowers.Abbreviations ABA
Abscisic acid
- GA
Gibberellin
- GC-MS-SIM
Gas chromatography-mass spectrometry-selected ion monitoring
- IAA
Indole-3-acetic acid
- ms33
Male sterile33
mutant
- PP333
Paclobutrazol
- WT
Wild type 相似文献
2.
In vitro culture is an important aid for ex situ conservation of rare, endemic or threatened plants. In this work, we establish an efficient method for the seed germination,
seedling development, and axillary shoot propagation of Centaurea zeybekii Wagenitz. The seeds, collected from a wild population, were surface sterilised and cultured on various in vitro germination media. The effects of photoperiod and temperature on seed germination were also investigated. Germinations were
obtained after 6 weeks in culture and the radicle emergence was evaluated as a main indicator. A high frequency of germination
was obtained on distilled water supplemented with vitamines and 1 mg/L GA3. Although the seed germination frequencies were not affected by photoperiod, the highest germination frequency was obtained
at 24 ± 2°C. A high frequency of axillary shoot proliferation was produced on MS medium supplemented with 1 mg/L BA. Then,
the axillary shoots were separated and transferred to MS medium with or without plant growth regulators for rooting. Rhizogenezis
was promoted after 6 weeks only in MS and 1/2 MS media containing 0.5 mg/L IBA. The rooting process was very slow and the
percentage of shoot rooting was also very low (15%).
The present study not only enables reinforcement of wild plant populations using ex situ growth of individuals, but it also helps to large number of aseptic seedling to use it in clonaly micropropagation studies. 相似文献
3.
Filipendula ulmaria (L.) Maxim (meadowsweet) is a medicinal plant that is claimed to have several biological activities, including anti-tumor,
anti-carcinogenic, anti-oxidant, anti-coagulant, anti-ulcerogenic, anti-microbial, anti-arthritic, and immunomodulatory properties.
This report describes, for the first time, an efficient plant regeneration system for F. ulmaria via adventitious shoot development from leaf, petiole, and root explants cultured on Murashige and Skoog’s minimal organics
medium containing different concentrations of thidiazuron (TDZ), benzyladenine, and kinetin either alone or in combination
with different auxins. Relatively extensive/prolific shoot regeneration was observed in all three explant types with TDZ in
combination with indole-3-acetic acid (IAA). Gibberellic acid (GA3), TDZ, and IAA combinations were also tested. The best shoot proliferation was observed among root explants cultured on media
supplemented with 0.45 μM TDZ + 2.85 μM IAA + 1.44 μM GA3. Regenerated shoots were transferred to rooting media containing different concentrations of either IAA, indole-3-butyric
acid (IBA), naphthalene acetic acid, or 2,4-dichlorophenoxyacetic acid. Most shoots developed roots on medium with 2.46 μM
IBA. Rooted explants were transferred to vermiculite in Magenta containers for a 2-wk acclimatization period and then finally
to plastic pots containing potting soil. The plantlets in soil were kept in growth chambers for 2 wk before transferring to
greenhouse conditions. 相似文献
4.
In the present report, we described the effects of indole-3-acetic acid (IAA), zeatin (ZT), gibberellin (GA3), and abscisic acid (ABA) on in vitro pollen germination and pollen tube growth in Torenia fournieri L. The results showed that IAA and GA3 stimulated in vitro pollen tube growth, ABA inhibited pollen tube growth, and ZT had no significant effect on the process.
The stimulating effect of exogenous IAA was particularly distinct, and led to synchronous growth of straighter and more slender
pollen tubes compared with the controls. However, no significant changes were found in the germination of the treated pollen.
The auxin efflux inhibitor, 10 μM 1-N-naphthylphthalamic acid (NPA), was also found to stimulate pollen tube growth. We measured the content of hormones (free
IAA, ZT, GA3, and ABA) in the stigmas and styles before and after pollination. The hormone contents of stigmas measured 0.5 h after pollination
(0.5 HAP) showed that ABA content decreased, whereas the content of IAA, ZT, or GA3 did not change significantly. The hormone level in pollinated styles (4 HAP) when pollen tubes had grown into the middle
part of style was characterized by an increase in free IAA and GA3 and a decrease in ABA, which was in agreement with the results that IAA and GA3 promoted but ABA inhibited pollen tube growth in vitro. Furthermore, the change of IAA level in styles was most notable, which
was accordant to the fact that auxin stimulated significantly pollen tube growth in vitro. Using immunoenzyme and immunogold
labeling techniques and an anti-IAA monoclonal antibody, we confirmed that free IAA was present throughout style tissues,
and distributed in the nucleus and cytoplasm of style cells. All these results suggested that hormones, especially IAA, play
important roles in pollen tube growth of T. fournieri.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
5.
Unimbibed Amaranthus caudatus seeds were found to contain stachyose, raffinose, verbascose, sucrose, galactinol, myo-inositol, glucose and fructose, while no galactose, maltose and maltotriose was detected. During imbibition, seed concentrations
of verbascose, stachyose, raffinose, galactinol, myo-inositol (temporary) and fructose (transient) were observed to decrease; concentrations of galactose and maltose remained
fairly constant, while those of sucrose, glucose and maltotriose increased, the increase in sucrose concentration was only
temporary. Effects of gibberellin A3 (GA3) at 3 × 10−4 M and ethephon at 3 × 10−4 M alone or in the presence of methyl jasmonate (Me-JA) at 10−3 M on concentrations of soluble sugars during germination of A. caudatus seeds were examined. Me-JA was found to inhibit seed germination and fresh weight of the seeds, but did not affect sucrose,
myo-inositol, galactose and maltose concentrations during imbibition for up to 20 h. The exogenously applied GA3 was observed to enhance germination, stachyose breakdown and glucose concentration after 20 h of incubation. Ethephon stimulated
seed germination as well as utilisation of stachyose, galactinol (both after 14 and 20 h) and raffinose (after 14 h of incubation).
Although the stimulatory effect of either GA3 or ethephon on seed germination was blocked by Me-JA; these stimulators increased mobilisation of raffinose and stachyose,
but only ethephon enhanced both glucose and fructose after 14 and/or 20 h of incubation in the presence of Me-JA. The maltose
concentration was increased by both GA3 and ethephon alone and in the presence of Me-JA. Of the growth regulators studied, ethephon alone and/or in combination with
Me-JA significantly increased the concentrations of glucose, fructose, galactose, maltose and maltotriose. The differences
in sugar metabolism appear to be linked to ethylene or GA3 applied simultaneously with Me-JA. 相似文献
6.
K. Samuel D. Debashish B. Madhumita G. Padmaja Siva Ram Prasad V. Bhaskara Ramana Murthy P. S. Rao 《In vitro cellular & developmental biology. Plant》2009,45(4):466-473
The propagation of Givotia rottleriformis Griff. is difficult as a result of long seed dormancy associated with poor seed germination. The present study was undertaken
to develop a protocol to overcome seed dormancy by culture of zygotic embryo axes and then develop an efficient method for
micropropagation of Givotia. Best germination frequency (78.3%) was achieved from mature zygotic embryo axes isolated from acid-scarified fresh seeds
when cultured on Murashige and Skoog (MS) medium (half-strength major salts) with 28.9 μM gibberellic acid (GA3). Efficient plant conversion was achieved by transfer of 10-d-old germinated embryos to MS medium (half-strength major salts)
supplemented with 1.2 μM kinetin (KN) and 0.5 μM indole-3-butyric acid (IBA). However, acid scarification of 1-yr-old seeds
decreased the germination frequency of zygotic embryo axes in comparison to those obtained from non-acid-scarified seeds which
germinated (96.2%) and converted into plants (80.3%) on MS basal (half-strength major salts) medium. Multiple shoot bud induction
was achieved by culture of shoot tips derived from in vitro germinated seedlings on MS medium with 0.5 μM thidiazuron for 4 wk, and the shoots elongated after transfer to a secondary
medium with 1.2 μM KN. A maximum number of 7.8 shoots per explant with an average shoot length of 3.2 cm was achieved after
two subcultures on this medium. The in vitro regenerated shoots rooted (41.5%) on half-strength MS medium with 0.5 μM IBA. The in vitro generated seedlings and micropropagated plants were established in soil with a survival frequency of 70% and 60%, respectively. 相似文献
7.
Acaulescent species of Streptocarpus Lindl. show unusual patterns of growth, characterized by anisocotyly (i.e. the unequal growth of cotyledons after germination)
and lack of a conventional embryonic shoot apical meristem (SAM). A SAM-like structure appears during post-embryonic development
on the axis of the continuously growing cotyledon. Since we have shown previously that KNOX genes are involved in this unusual morphology of Streptocarpus rexii, here we investigated the expression pattern of WUSCHEL (WUS), which is also required for the indeterminacy of the SAM, but is expressed independently from KNOX in Arabidopsis thaliana. In A. thaliana WUSCHEL is involved in the maintenance of the stem cell fate in the organizing centre. The expression pattern of the WUS ortholog in S. rexii (SrWUS) strongly deviates from that of the model plant, suggesting a fundamentally different spatial and temporal regulation of signalling
involved in meristem initiation and maintenance. In S. rexii, exogenous application of growth regulators, i.e. gibberellin (GA3), cytokinin (CK) and a gibberellin biosynthesis inhibitor (PAC), prevents anisocotyly and relocates meristematic cells to
a position of conventional SAMs; this coincides with a re-localization of the two main pathways controlling meristem formation,
the SrWUS and the KNOX pathways. Our results suggest that the establishment of a hormone imbalance in the seedlings is the basis of
anisocotyly, causing a lateral dominance of the macrocotyledon over the microcotyledon. The peculiar morphogenetic program
in S. rexii is linked to this delicate hormone balance and is the result of crosstalk between endogenous hormones and regulatory genes.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
8.
Glucose delays seed germination in<Emphasis Type="Italic"> Arabidopsis thaliana</Emphasis> 总被引:9,自引:0,他引:9
Here we report that glucose delays germination of Arabidopsis thaliana (L.) Heynh. seeds at concentrations below those known to inhibit early seedling development. This inhibition acts on embryo growth and is independent of hexokinase (HXK) function. Hormones and hormone inhibitors were applied to the germination media and several hormone biosynthesis and signalling mutants were tested on glucose media to investigate a possible role of abscisic acid (ABA), gibberellin and ethylene in the glucose-induced germination delay. Results indicate that the germination inhibition by glucose cannot be antagonized by ethylene or gibberellin and is independent of the HXK1/ABA/ABI4 signalling cascade. These findings suggest that there is a separate regulatory pathway independent of ABI2/ABI4/ABI5. Thus, in a relatively short time frame sugars utilize different signalling cascades to inhibit germination and post-germination growth, underlining the complexity of sugar responses.Abbreviations
ABA
Abscisic acid
-
ABI
ABA insensitive
-
ACC
1-Aminocyclopropane-1-carboxylic acid
-
BR
Brassinosteroid
-
CAB
Chlorophyll a/b-binding protein
-
FUS3
Fusca3
-
GA
Gibberellin
-
GA
3
Gibberellic acid
-
HXK
Hexokinase
-
LEC1
Leafy cotyledon1
-
RBCS
Ribulose-1,5-bisphosphate carboxylase small subunit
-
WT
Wild type 相似文献
9.
Flixweed is one of the most abundant weeds in North America and China, and causes a reduction in crop yields. Dormancy of flixweed seeds is deep at maturity and is maintained in soil for several months. To identify regulators of seed dormancy and germination of flixweed, the effect of environmental and hormonal signals were examined using dormant and non-dormant seeds. The level of dormancy was decreased during after-ripening and stratification, but long imbibition (over 5 days) at 4 °C in the dark resulted in the introduction of secondary dormancy. The strict requirement of duration of cold treatment for the break of dormancy may play a role in the seasonal regulation of germination. The germination of non-dormant flixweed seeds was critically regulated by red (R) and far-red (FR) light in a photoreversible manner. Sodium nitroprusside, a donor of nitric oxide (NO), promoted germination of half-dormant seeds, suggesting that NO reduced the level of seed dormancy. As has been shown in other related species, light elevated sensitivity to GA4 in dark-imbibied flixweed seeds, but cold treatment did not affect GA4-sensitivity unlike in Arabidopsis. Taken together, our results indicate that seed germination in flixweed and its close relative Arabidopsis is controlled by similar as well as distinct mechanisms in response to various endogenous and environmental signals. 相似文献
10.
Perrig D Boiero ML Masciarelli OA Penna C Ruiz OA Cassán FD Luna MV 《Applied microbiology and biotechnology》2007,75(5):1143-1150
We evaluated phytohormone and polyamine biosynthesis, siderophore production, and phosphate solubilization in two strains
(Cd and Az39) of Azospirillum brasilense used for inoculant formulation in Argentina during the last 20 years. Siderophore production and phosphate solubilization
were evaluated in a chemically defined medium, with negative results. Indole 3-acetic acid (IAA), gibberellic acid (GA3), and abscisic acid (ABA) production were analyzed by gas chromatography-mass spectrometry. Ethylene, polyamine, and zeatin
(Z) biosynthesis were determined by gas chromatography-flame ionization detector and high performance liquid chromatography
(HPLC-fluorescence and -UV), respectively. Phytohormones IAA, Z, GA3, ABA, ethylene, and growth regulators putrescine, spermine, spermidine, and cadaverine (CAD) were found in culture supernatant
of both strains. IAA, Z, and GA3 were found in all two strains; however, their levels were significantly higher (p < 0.01) in Cd (10.8, 2.32, 0.66 μg ml−1). ABA biosynthesis was significantly higher (p < 0.01) in Az39 (0.077 μg ml−1). Ethylene and polyamine CAD were found in all two strains, with highest production in Cd cultured in NFb plus l-methionine (3.94 ng ml−1 h−1) and Az39 cultured in NFb plus l-lysine (36.55 ng ml−1 h−1). This is the first report on the evaluation of important bioactive molecules in strains of A. brasilense as potentially capable of direct plant growth promotion or agronomic yield increase. Az39 and Cd showed differential capability
to produce the five major phytohormones and CAD in chemically defined medium. This fact has important technological implications
for inoculant formulation as different concentrations of growth regulators are produced by different strains or culture conditions. 相似文献
11.
Jung Eun Hwang Joon Ki Hong Ji Hyun Je Kyun Oh Lee Dool Yi Kim Sang Yeol Lee Chae Oh Lim 《Plant cell reports》2009,28(11):1623-1632
Phytocystatins are cysteine proteinase inhibitors in plants that are implicated in the endogenous regulation of protein turnover
and defense mechanisms against insects and pathogens. A cDNA encoding a phytocystatin called AtCYS6 (Arabidopsis thaliana phytocystatin6) has been isolated. We show that AtCYS6 is highly expressed in dry seeds and seedlings and that it also accumulates
in flowers. The persistence of AtCYS6 protein expression in seedlings was promoted by abscisic acid (ABA), a seed germination
and post-germination inhibitory phytohormone. This finding was made in transgenic plants bearing an AtCYS6 promoter–β-glucuronidase (GUS) reporter construct, where we found that expression from the AtCYS6 promoter persisted after ABA treatment but was reduced under control conditions and by gibberellin4+7 (GA4+7) treatment during the germination and post-germinative periods. In addition, constitutive over-expression of AtCYS6 retarded germination and seedling growth, whereas these were enhanced in an AtCYS6 knock-out mutant (cys6-2). Additionally, cysteine proteinase activities stored in seeds were inhibited by AtCYS6 in transgenic Arabidopsis. From these data, we propose that AtCYS6 expression is enhanced by the germination inhibitory phytohormone ABA and that it participates in the control of germination
rate and seedling growth by inhibiting the activity of stored cysteine proteinases. 相似文献
12.
Summary We describe an in vitro propagation protocol for Zingiber petiolatum (Holttum), I. Theilade, a rare species from the southern part of Thailand. Fruits were surface-sterilized and seeds germinated
on Murashige and Skoog medium (MS) medium supplemented with 3% sucrose. Three-month-old seedlings were used as initial plant
material for in vitro propagation. Terminal buds of the plants were inoculated on MS medium containing 6-benzylaminopurine (BA; 2.2–35.5 μM) alone or in combination with 1-naphthaleneacetic acid (0.5 μM). Eight weeks after inoculation, the cultures were transferred to MS medium without plant growth regulators for 4wk. The
cultures transferred from MS medium with 17.8 μM BA revealed the highest shoot induction rate of 6.1±0.7 shoots per explant. Rooting was spontaneously achieved in MS medium
without plant growth regulators. Rooted plants were successfully transplanted to soil. 相似文献
13.
Summary
In vitro methods were applied to the only remaining plant of the Meelup Mallee (Eucalyptus phylacis), a critically endangered species from the southwest of Western Australia. Shoot explants were initiated into culture using
a 1/2 MS [Murashige and Skoog basal medium (BM) for all experiments] liquid medium supplemented with 1% (w/v) activated charcoal,
which was replenished twice daily, followed by transfer of explants to agar medium supplemented with 0.5 μM zeatin. Explants were cultured under low intensity lighting (PPFD of 5–10 μmol m−2s−1) to minimize blackening of tissues, and some explants were induced to produce nodular green calluses in response to BM supplemented
with 5 μM thidiazuron. Nodular green calluses were induced to form adventitious shoots following transfer to medium supplemented with
0.5 μM zeatin and 1 μM gibberellic acid, A4 isomer (GA4). Development of shoots was completed on 1 μM zeatin + 0.1 μM 6-benzylaminopurine (BA) in vented culture tubes. Regenerated shoots were sequentially cultured on medium containing 0.5
μM zeatin + 0.2 μM indoleacetic acid (IAA) followed by either 0.5 μM zeatin + 1μM GA4 for shoot elongation or 1 μM zeatin + 0.5 μM IAA to optimize shoot growth. Rooted microshoots were produced after 4 weeks on 5 μM indolebutyric acid (IBA) and survived acclimatization and transfer to potting mixture. 相似文献
14.
The influence of after-ripening, sodium nitroprusside, potassium ferricyanide, cyanide, paclobutrazol and nitrite on germination
of seeds of Nicotiana benthamiana was investigated as well as the influence of plant hormones such as gibberellins and abscisic acid. Dormancy of N. benthamiana seeds was broken by all treatments except treatments with abscisic acid, paclobutrazol and gibberellic acid (GA3). Gibberellins had an interesting effect on dormancy breakage of studied seeds which was dependent on use of particular gibberellin:
GA3 or GA4+7. Unlike GA3, GA4+7 had broken seed dormancy. 相似文献
15.
16.
Investigations on seeds of Scrophularia marilandica L. were undertaken to determine their germination requirements. Seeds were collected from three naturally occurring sites
and one greenhouse-grown population in London, Ontario in September and October of 1997. Some were set to germinate immediately
after collection; others were stored in or on soil outside and/or under controlled laboratory conditions before testing. Germination
was assessed under two light/temperature regimes (35°C 14 h light, 20°C 10 h dark and 25°C 14 h light, 10°C 10 h dark), in
continuous darkness, and in the presence of two germination-promoting chemicals (GA3 and KNO3). Fresh seeds germinated best at 35/20°C, while stored seeds germinated best at 25/10°C. No differences in percent germination
were found among three seed-maturity stages. All chemical treatments, except 0.01 M KNO3, increased percent germination. Significant differences were found both among and within sites for most chemical treatments,
but exposure to 3 × 10−4 M GA3 caused almost every seed to germinate. When compared to the control, both the gibberellic acid and the soil-storage treatments
contributed to faster germination. Exposure of seeds to naturally prevailing conditions on the soil surface followed by testing
under the 25/10°C regime produced the highest percent germination. No seeds germinated in the dark. In summary, seeds of S. marilandica exhibit physiological dormancy, which can be alleviated by exposure to light, after-ripening and/or cold stratification.
It is probable that the differences in germination response among sites can be attributed to differences in environmental
conditions during seed production. These experiments indicate that the seeds of S. marilandica must be buried shortly after dispersal in order to form a persistent seed bank. 相似文献
17.
During the entire period of internode growth of Merremia emarginata contents of gibberellic acid (GA3), phenyl-acetic acid (PAA), indole-3-acetic acid (IAA, free and conjugated) and abscisic acid (ABA, free and conjugated)
were estimated by ELISA using polyclonal antibodies raised against each hormones. At the time of internode elongation free
auxin content was low and increased with the decrease in the rate of elongation. In contrast, conjugated IAA showed declining
trend where free IAA content was remarkably high, suggesting thereby that conjugated IAA might have mobilized during the later
phase of internode development. The endogenous GA3 contents were high as compared to other hormones; however, no significant role of GA3 was discernible in elongation growth. Conjugated ABA contents remained very low during the elongation growth and increased
thereafter. 相似文献
18.
The vhb gene encoding Vitreoscilla haemoglobin (VHb) was transferred to barley with the aim of studying the role of oxygen availability in germination and growth.
Previous findings indicate that VHb expression improves the efficiency of energy generation during oxygen-limited growth,
and germination is known to be an energy demanding growth stage during which the embryos also suffer from oxygen deficiency.
When subjected to oxygen deficiency, the roots of vhb-expressing barley plants showed a smaller increase in alcohol dehydrogenase (ADH) activity than those of the control plants.
This indicates that VHb plants experienced less severe oxygen deficiency than the control plants, possibly due to the ability
of VHb to substitute ADH for recycling NADH and maintaining glycolysis. In contrast to previous findings, we found that constitutive
vhb expression did not improve the germination rate of barley kernels in any of the conditions studied. In some cases, vhb expression even slowed down germination slightly. VHb production also appeared to restrict root formation in young seedlings.
The adverse effects of VHb on germination and root growth may be related to its ability to scavenge nitric oxide (NO), an
important signal molecule in both seed germination and root formation. Because NO has both cytotoxic and stimulating properties,
the effect of vhb expression in plants may depend on the level and role of endogenous NO in the conditions studied. VHb production also affected
the levels of endogenous barley haemoglobin, which may explain the relatively moderate effects of VHb in this study. 相似文献
19.
Scott L. Stewart Michael E. Kane 《In vitro cellular & developmental biology. Plant》2007,43(3):178-186
Orchid–mycobiont specificity in the Orchidaceae was considered controversial and not well understood for many years. Differences
in mycobiont specificity during germination in vitro vs in situ have lead some to consider orchid–mycobiont specificity as being generally low; however, others have suggested that specificity,
especially in vitro, is surprisingly high. Mycobiont specificity may be genus or species specific. An in vitro symbiotic seed germination experiment was designed to examine mycobiont specificity of the endangered Florida terrestrial
orchid Spiranthes brevilabris using mycobionts isolated from both the study species and the endemic congener Spiranthes floridana. In a screen of mycobionts, isolates Sflo-305 (99.5%), Sflo-306 (99.5%), and Sflo-308 (89.9%) (originating from S. floridana) supported higher initial (stage 1) seed germination than isolate Sbrev-266 (32.4%) (originating from S. brevilabris) after 3 wk culture. However, only isolate Sbrev-266 supported advanced germination and protocorm development to stage 5
(53.1%) after 12 wk culture. These findings suggest that S. brevilabris maintains a high degree of mycobiont specificity under in vitro symbiotic seed germination conditions. High orchid–mycobiont specificity in S. brevilabris may be indicative of the rare status of this orchid in Florida. 相似文献
20.
Giovanni Iapichino Marcello Airò 《In vitro cellular & developmental biology. Plant》2008,44(4):330-337
Multiple shoots were induced on stem segments of an 8-y-old plant of Metrosideros excelsa Sol ex Gaertn. “Parnel”. Axillary shoots produced on uncontaminated explants were excised, segmented, and recultured in the
same medium to increase the stock of shoot cultures. The Murashige and Skoog (MS) medium, augmented with different concentrations
of 2- isopenthenyladenine (2iP) and indole-3-acetic acid (IAA), either singly or in combinations, as potential medium for
shoot multiplication by nodal segments was tested. In the following experiment, equal molar concentrations of four cytokinins
[2iP, kinetin, zeatin, and N
6-benzyladenine (BA)] in combination with equal molar concentrations of three auxins [IAA, α-naphthaleneacetic acid (NAA),
and indole-3-butyric acid (IBA)] were tested for ability to induce axillary shoot development from single-node stem segments.
The highest rate of axillary shoot proliferation was induced on MS agar medium supplemented with 1.96μM 2iP and 1.14μM IAA
after 6 wk in culture. Different auxins (IAA, IBA, and NAA) were tested to determine the optimum conditions for in vitro rooting of microshoots. The best results were accomplished with IAA at 5.71μM (89% rooting) and with IBA at 2.85 or 5.71μM
(86% and 86% rooting, respectively). Seventy and 90 percent of the microshoots were rooted ex vitro in bottom-heated bench (22 ± 2°C) after 2 and 4 wk, respectively. In vitro and ex vitro rooted plantlets were successfully established in soil. 相似文献