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1.
Summary The majority of bamboos (Graminae) are arborescent and perennial. The erect stems (culms) of woody bamboos are useful for
a wide variety of purposes. Most bamboos flower only once at the end of very long vegetative growth phases and die afterwards.
Flowering in bamboos is thought to be under genetic control, occurring somewhat like an alarm clock, going off at a preset
time. The nature of this genetic clock and any interaction between the ‘internal clock’ and the environment are not yet known.
Because of this ‘peculiar’ flowering behavior, bamboo seeds are available only at very long intervals. Obtaining concurrent
flowering in two or more species (or varieties) in space and time is difficult, making perennial seed propagation and genetic
improvement by breeding nearly impossible. Besides, this peculiar flowering behavior of bamboos is also believed to have brought
the giant pandas to the verge of extinction. One of the spectacular developments in the area of bamboo genetic improvement
has been the precocious in vitro induction of flowering. By this method it has been possible to rapidly accelerate the reproductive
development (within 3–6 mo. versus 30–60 yr in nature). This has opened the possibility of perennial seed propagation and
hybridization. In vitro induction of flowering can be obtained by diverse methods which show some similarities and differences.
Induction of flowering is possible in cultures derived from both juvenile and mature explants. The proportion of seedlings
induced to flower is possibly influenced by genotypic variation, though the role of methods used cannot be ruled out. A cytokinin
or a shift in the auxin-cytokinin equilibrium is believed to bring about in vitro induction of flowering. The pH of the media
also has an influence. Induction of flowering and rhizogenesis is considered to be an antagonistic phenomenon in vitro. A
comparison between in vitro and in vivo flowering in Bambusa arundinacea has shown that though smaller, in vitro-induced florets are comparable to normal florets. There is reduced pollen fertility
and some impairment in pollen wall development. Biochemical studies on the in vitro-induced flowering in bamboos have shown
(1) selective expression of esterase and peroxidase isozymes during transition of nonembryogenic calluses to embryogenic calluses,
somatic embryo development, germination and subsequent flowering of somatic embryo derived shoots, and (2) minimal peroxidase
activity before rhizogenesis and induction of flowering in vitro. There are reports of published and comparable methods having
failed to induce flowering in vitro. 相似文献
2.
The lithic assemblage of La Garde offers the opportunity to observe a Final Acheulean series located in the Loire department (south-east France). The site was probably a multi-activity place asking large tools and flakes, according to the strategies used by humans. Three main categories of large bifacial tools mainly made of flint can be described, with a triangular or oval shape and with a transversal cutting edge. These tools are more bifacial-tools than bifaces through the kind of shaping and the retouches on the cutting edges. The Levallois flaking is associated to various other types of knapping. The site, located along a small valley, suggests a human circulating between the Saône-Rhône corridor and the interior basins of the Massif Central Mountains. The Rhodanian corridor yielded little evidence of Acheulean settlements while in the Centre of France, they are numerous. La Garde proves that systematic prospecting in this area will permit in future to complete the map of the Acheulean occupations in south-east France. 相似文献
3.
Bud break and multiple shoot formation from tissues of mature trees ofPinus caribaea andPinus kesiya
R. S. Nadgauda N. N. Nagarwala V. A. Parasharami A. F. Mascarenhas 《In vitro cellular & developmental biology. Plant》1993,29(3):131-134
Summary Proliferation of terminal and axillary buds of 20 yr-oldPinus caribaea andP. kesiya trees was obtained on half strength DCR medium supplemented with 0.5 mg·liter−1 6-benzylaminopurine (BA). These sprouts further elongated with the formation of multiple shoots with the ratio of 1:3, on
transfer to medium in which the 0.25 mg·liter−1 BA of the initiation medium was replaced by 0.25 mg·liter−1 kinetin. Rooting was obtained on the same medium. Plantlets thus formed were transferred to perlite:peat:vermiculite mixture
(1:1:1) in polybags (10×5 cm) under 80±5% humidity in a polyhouse. Plantlets ofP. caribaea andP. kesiya were established with 72.5 and 83.3% survival, respectively. 相似文献
4.
In vitro plantlet regeneration from mature zygotic embryos of Pinus wallichiana A.B. Jacks 总被引:4,自引:0,他引:4
Plantlet regeneration was achieved in blue pine (Pinus wallichiana A.B. Jacks) by organogenesis of mature zygotic embryos. The effect of various basal media and five cytokinins on adventitious
bud induction, development and elongation was investigated. Half-strength Douglas fir cotyledon revised medium (DCR) supplemented
with 2.5 μm N6-benzyladinine (BA) and 0.025 μM thidiazuron was found to be most effective in inducing adventitious buds. The effect of a
BA pulse treatment was also tested, and the bud-forming capacity of each treatment was quantified. The elongation of adventitious
buds was achieved on hormone-free half-strength DCR medium containing 2% sucrose and 0.05% activated charcoal. Rooting was
induced in the elongated shoots with a 6-h treatment of indoleacetic acid and indolebutyric acid solutions (1 mM each). Rooted
shoots were transplanted in the greenhouse for hardening and their survival percentage was 64.4 after 5 weeks and 45.7 after
6 months.
Received: 11 September 1998 / Revision received: 10 February 1999 / Accepted: 26 February 1999 相似文献
5.
Nadgauda Rajani S. John C. K. Parasharami V. A. Joshi M. S. Mascarenhas A. F. 《Plant Cell, Tissue and Organ Culture》1997,48(3):181-188
Seedling explants of Bambusa arundinacea were cultured in a Murashige & Skoog (MS) based liquid medium, supplemented with
sucrose (2), coconut water (5) and 6-benzylaminopurine (2.2 μM). In 3–6 months about 70 of the cultures flowered. A comparison
was made between in vitro and in vivo flowering. Though smaller in size, in vitro florets were morphologically comparable
to the in vivo florets. Anthesis in in vivo flowering took place in the morning hours. It was more or less synchronized and
was dependent on the atmospheric temperature and humidity. The lemma and palea opened to expose both androecium and gynoecium
to the pollinating agent (wind). In in vitro flowering, some florets opened as in their in vivo counterparts, some did not
open but the anthers protruded from the tip of the partially opened lemma and palea. Anthesis was not synchronized under in
vitro conditions. Pollen fertility in in vivo and in vitro flowerings were approximately 93 and 31 respectively. Studies by
scanning electron microscopy showed some discrepancies in the pollen wall development in vitro. The trifid stigmas of in vivo
florets were highly feathery with many papillae and withered soon after pollination or within few hours. The stigmas of in
vitro developed florets were smaller with fewer and stouter papillae. They remained turgid for relatively longer periods.
Seed production in in vivo flowering was profuse whereas in in vitro flowering seeds were produced only when many florets
opened at the same time, in the same culture vessel.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
6.
Turmeric (Curcuma longa L.) is an important spice crop plant that is sterile and cannot be improved by conventional breeding. An efficient method
for stable transformation for turmeric, C. longa L., was developed using particle bombardment. Callus cultures initiated from shoots were bombarded with gold particles coated
with plasmid pAHC25 containing the bar and gusA genes each driven by the maize ubiquitin promoter. Transformants were selected on medium containing glufosinate. Transgenic
lines were established on selection medium from 50% of the bombarded calluses. Transgenic shoots regenerated from these were
multiplied and stably transformed plantlets were produced. Polymerase chain reaction (PCR) and histochemical GUS assay confirmed
the stable transformation. Transformed plantlets were resistant to glufosinate. 相似文献
7.
M. M. Jana R. S. Nadgauda K. Rajmohan A. F. Mascarenhas 《In vitro cellular & developmental biology. Plant》1994,30(1):55-57
Summary A method for rapid production of somatic embryos having normal developmental morphology, from the nucellar tissue of three
monoembryonic Indian mango varieties, namely, Alphonso, Mundan and Baneshan was developed. Somatic embryogenesis could be
induced using Murashige and Skoog (MS) medium supplemented with 2,4-dichlorophenoxyacetic acid (2,4-D) 5.0 mg/liter (22.62
μM, gibberellic acid (GA3) 5.0 mg/liter (14.43 μM), sucrose 60 g/liter and activated charcoal (AC) 2.5 g/liter. Maturation of embryos was observed in a reduced concentration
of basal medium supplemented with abscisic acid 1.0 mg/liter (3.78 μM) coconut water 20 percent (vol/vol) casein hydrolysate (CH) 100.0 mg/liter, sucrose 40.0 g/liter and activated charcoal 2.5
g/liter. N6-benzyladenine (BA) 5.0 mg/liter (22.2 μM) favored normal germination of the embryos. Plant development was complete in 75 to 80 days. 相似文献
8.
A procedure has been described for the large-scale micropropagation of three Phragmites species, P. karka, P. communis and P. australis, from axillary buds excised from the main and side branches. Position of the buds on the branches had an effect on the bud
break and establishment of the cultures under in vitro conditions. Lower buds of P. australis and middle buds of P. karka and P. communis were the most suitable. The presence of yeast extract as one of the ingredients of the sprouting medium helped in the early
detection of systemic contamination. Multiple shoot formation and root initiation were obtained on Murashige and Skoog's basal
medium supplemented with different concentrations of BA – 0.5 mg/l for P. karka, 0.25 mg/l for P. communis and 0.1 mg/l for P. australis– 0.5 mg/l Kn and 2% sucrose (w/v). Shoots and roots elongated on half-strength MS basal medium with 2% sucrose but without
any plant growth regulators. A zone of root hair was observed in the case of P. australis. Hardening occurred on 95% of the plantlets within 30 days of transfer to the polyhouse. Over 10,000 plants were produced
from three buds of each species within 9 months. The plants were supplied to a private company for their industrial waste
treatment.
Received: 1 June 1998 / Revision received: 28 August 1998 / Accepted: 10 October 1998 相似文献
9.
Stable transformation of mature zygotic embryos and regeneration of transgenic plants of chir pine (Pinus roxbughii Sarg.) 总被引:1,自引:0,他引:1
A particle inflow gun was used to transfer the plasmid pAHC25 containing the bar gene conferring resistance to glufosinate and the gusA reporter gene, each driven by the maize ubiquitin promoter, to mature embryos of Pinus roxburghii (chir pine). High levels of transient expression were obtained when embryos were cultured for 6 days on 10 μM benzyl adenine-containing medium and then exposed to high osmoticum (0.5 M sucrose) before and after bombardment. Selection on medium containing Basta enabled recovery of stably transformed shoots, both from the epicotyl and from adventitious buds. The primary transformed shoots from the epicotyl were multiplied via axillary shoots. Transformation was confirmed by histochemical staining for β-glucuronidase (GUS) activity, by polymerase chain reaction (PCR) amplification of fragments of gusA and nos terminator, and by the resistance of needles to Basta. 相似文献
10.
Embryogenic cultures of chir pine (Pinus roxburghii Sarg.) were cryopreserved successfully in liquid nitrogen. It was found that using sorbitol and dimethyl sulfoxide (DMSO)
as cryoprotectants was essential for the survival of the tissue. Among the different concentrations of the cryoprotectants
used, the most effective treatment was observed to be 0.3 M sorbitol and 5 % DMSO. On staining the cryopreserved tissue with
fluorescein diacetate, it was observed that only a few meristematic embryo heads survived and resumed growth after a very
short initial lag phase. The recovered cultures showed normal regrowth on proliferation medium and, it was also observed that
washing off the cryoprotectants was necessary for the cultures to survive. The results indicate that cryopreservation can
be used for conserving the germplasm, and in maintaining the embryogenic capacity of the tissue.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献