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1.
Shoot organogenesis is one of the in vitro plant regeneration pathways. It has been widely employed in plant biotechnology for in vitro micropropagation and genetic transformation, as well as in study of plant development. Morphological and physiological aspects of in vitro shoot organogenesis have already been extensively studied in plant tissue culture for more than 50 years. Within the last ten years, given the research progress in plant genetics and molecular biology, our understanding of in vivo plant shoot meristem development, plant cell cycle, and cytokinin signal transduction has advanced significantly. These research advances have provided useful molecular tools and resources for the recent studies on the genetic and molecular aspects of in vitro shoot organogenesis. A few key molecular markers, genes, and probable pathways have been identified from these studies that are shown to be critically involved in in vitro shoot organogenesis. Furthermore, these studies have also indicated that in vitro shoot organogenesis, just as in in vivo shoot development, is a complex, well-coordinated developmental process, and induction of a single molecular event may not be sufficient to induce the occurrence of the entire process. Further study is needed to identify the early molecular event(s) that triggers dedifferentiation of somatic cells and serves as the developmental switch for de novo shoot development. 相似文献
2.
Passiflora alata in vitro organogenesis was studied based on explant type, culture medium composition, and incubation conditions. The results indicated
that the morphogenic process occurred more efficiently when hypocotyl segment-derived explants were cultured in media supplemented
with cytokinin and AgNO 3 incubated under a 16-h photoperiod. The shoot bud elongation and plant development were obtained by transferring the material
to MSM culture medium supplemented with GA 3 and incubated in flasks with vented lids. Histological analyses of the process revealed that the difficulties in obtaining
plants could be related to the development of protuberances and leaf primordia structures, which did not contain shoot apical
meristem. Roots developed easily by transferring elongated shoots to 1/2 MSM culture medium. Plant acclimatization occurred
successfully, and somaclonal variation was not visually detected. The efficiency of this organogenesis protocol will be evaluated
for genetic transformation of this species to obtain transgenic plants expressing genes that can influence the resistance
to Cowpea aphid borne mosaic virus. 相似文献
3.
AbstractFlowering is the most elusive and fascinating of all plant developmental processes. The ability to induce flowering in vitro in orchids would reduce the relatively long juvenile phase and provide deeper insight into the physiological, genetic and molecular aspects of flowering. This review synthesizes all available studies that have been conducted on in vitro flowering of orchids with the objective of providing valuable clues as to the mechanism(s) that is possibly taking place. 相似文献
4.
In vitro shoot regeneration from sunflower cotyledonary explants can be obtained in the presence of kinetin and indole-3-acetic acid.
In contrast, callus proliferation is obtained in the presence of 2,4-dichlorophenoxyacetic acid on culture medium. The purpose
of this study was to investigate changes in protein profiles during callus and shoot development from cotyledonary explants
and to correlate them with ontogenic stages during in vitro culture. Cotyledons cultured in the presence of 2,4-dichlorophenoxyacetic acid produced friable callus as a result of early
division of parenchymatic cells associated with the vascular bundles of the explant. The callogenic ability was independent
of the cotyledonary region used as starting explant. Direct shoot organogenesis was observed from the same type of cells growing
in culture media supplemented with kinetin and indole-3-acetic acid. In this case, the regeneration potential varied among
regions from which the explants were obtained. Protein profiles revealed differences associated with shoots or callus developmental
programs. A 27-kDa polypeptide was uniquely detected in the explants undergoing shoot organogenesis. The amount of this polypeptide
during the first 4 d of culture increased and was followed by the appearance of meristematic centers in histologically analyzed
samples. This polypeptide could be used as a specific marker for in vitro shoot development in this species. 相似文献
5.
Culture of Papaver somniferum in vitro was used for a characterisation of cell surface structures and mode of cell adhesion and cell separation during cell differentiation
and plant regeneration in somatic embryogenesis and shoot organogenesis. In early stages of somatic embryogenesis, cell type-specific
and developmentally regulated change of cell morphogenesis was demonstrated. Cell wall of separated embryonic cells were self-covered
with external tubular network, whereas morphogenetic co-ordination of adhered cells of somatic proembryos was supported by
fine and fibrillar external cell wall continuum of peripheral cells, interconnecting also local sites of cell separation.
Such type of cell contacts disappeared during histogenesis, when the protodermis formation took place. Tight cell adhesion
of activated cells with polar cell wall thickening, and production of extent mucilage on the periphery were the crucial aspects
of meristemoids. Fine amorphous layer covered developing shoot primordia, but we have not observed such comparable external
fibrillar network. On the contrary intercellular separation of differentiated cells in regenerated organs, and accepting distinct
developmental system of somatic embryogenesis and shoot organogenesis, cell adhesion in early stages and ultrastructural changes
associated with tissue disorganisation, and the subsequent reorganisation into either embryos or shoots appear to be regulatory
morphogenetical events of plant regeneration in vitro. 相似文献
7.
Vigorous organogenesis can be induced from hypocotyl and root explants of Arabidopsis thaliana using a two-step culture procedure consisting of preculture on callus-inducing medium (CIM) and subsequent culture on shoot-inducing medium (SIM) or root-inducing medium (RIM). With this culture system, we examined the influence of 5-bromo-2′-deoxyuridine (BrdU), a thymidine (dT) analogue, on plant organogenesis in vitro. Treatment with BrdU during SIM or RIM culture had negative effects on shoot and root redifferentiation over a broad range of concentrations. When explants were exposed to low concentrations of BrdU during preculture and then transferred onto BrdU-free SIM, shoot redifferentiation was accelerated significantly. At higher doses, BrdU treatment during the pre-culture inhibited shoot redifferentiation strongly in hypocotyl explants, but not in root explants. This suggests that a target of the BrdU action lies within the process of acquisition of cell proliferation competence specifically involved in hypocotyl dedifferentiation. These effects of BrdU were counteracted by the simultaneous addition of excess dT. BrdU-pretreated and untreated explants did not differ significantly in the phytohormone dependency of shoot redifferentiation. Our results provide a basis for future studies on plant organogenesis combining pharmacological analysis with BrdU as a probe and molecular genetics with Arabidopsis mutants. 相似文献
8.
Plant somatic cells have the capability to switch their cell fates from differentiated to undifferentiated status under proper
culture conditions, which is designated as totipotency. As a result, plant cells can easily regenerate new tissues or organs
from a wide variety of explants. However, the mechanism by which plant cells have such remarkable regeneration ability is
still largely unknown. In this study, we used a set of meristem-specific marker genes to analyze the patterns of stem cell
differentiation in the processes of somatic embryogenesis as well as shoot or root organogenesis in vitro. Our studies furnish preliminary and important information on the patterns of the de novo stem cell differentiation during various types of in vitro organogenesis. 相似文献
9.
Pogonatherum paniceum (Poaceae) is a perennial plant with good potential for eco-recovery and ornamental function. This study presents in vitro
culture systems of simple hormonal regulation of somatic embryogenesis and shoot organogenesis from mature caryopses. Mature
caryopses of P. paniceum were grown on Murashige and Skoog medium with 3% sucrose (w/v) and various concentrations or combinations of 2,4-dichlorophenoxyacetic
acid (2,4-D), α-naphthaleneacetic acid (NAA) and 6-benzylaminopurine (BAP). Morphological development was analyzed by light
microscope after histological sectioning. Four types of callus were induced by different concentrations of 2,4-D. Type I callus
was regenerated via somatic embryogenesis; type II callus failed to produce any regeneration; type III callus had both somatic
embryogenesis and shoot organogenesis capacities; and type IV callus only displayed shoot organogenesis capacity. Regarding
hormone combinations used in this study, NAA only induced type IV callus and BAP only induced direct multiple shoot formation.
The combinations of 2,4-D and NAA induced type III callus. Several of the regeneration pathways were simply controlled by
one or two kinds of plant hormones. The established systems will be helpful for further research on the developmental mechanism
of switch between somatic embryogenesis and shoot organogenesis. 相似文献
10.
Summary The gaseous phytohormone ethylene regulates many aspects of plant morphogenesis. Growth and development of cells cultured in vitro are largely dependent on the presence of phytohormones, including ethylene in the culture environment. Hence, modification
of phytohormone composition and interaction in the nutrient medium has been the primary strategy to manipulate morphogenesis in vitro. Such studies have shown the importance of ethylene, as well as the inhibition of its synthesis or action, in growth and
organized development in vitro, including xylogenesis, organogenesis, somatic embryogenesis, and androgenesis. More recently, mutants and transgenic plants
have been used to elucidate the role of ethylene in various cellular and developmental processes. In this review, we concentrate
on the more recent advances in the study of ethylene in plant morphogenesis in vitro. We also include information about the various chemical modulators of ethylene biosynthesis and action employed in plant
tissue culture. 相似文献
11.
In vitro shoot organogenesis and plant regeneration are crucial for both plant biotechnology and the fundamental study of plant biology. Although the importance of auxin and cytokinin has been known for more than six decades, the underlying molecular mechanisms of their function have only been revealed recently. Advances in identifying new Arabidopsis genes, implementing live-imaging tools and understanding cellular and molecular networks regulating de novo shoot organogenesis have helped to redefine the empirical models of shoot organogenesis and plant regeneration. Here, we review the functions and interactions of genes that control key steps in two distinct developmental processes: de novo shoot organogenesis and lateral root formation. 相似文献
12.
Higher plant shoot meristems are multicellular structures that are the site of postembryonic organogenesis. Analysis of chimeric plants has indicated that cells in different regions of the meristem can interact with each other so that their activities are coordinated during developmental processes. Correlations have not been demonstrated between events at a molecular level and the interactions observed at a phenotypic level in chimeras. Two recent papers (1,2) address this problem by reporting that expression of the floricaula gene in one region of chimeric snapdragon meristems is sufficient to promote the transition from inflorescence to floral development and to induce the expression of the downstream organ identity genes deficiens and plena throughout the meristem. 相似文献
14.
The epiphyte Pseudomonas syringae pv. syringae 22d / 93 (Pss22d), isolated from soybean leaves, had been characterized as a promising and species‐specific biocontrol strain in vitro and in planta against the plant pathogen P. syringae pv. glycinea (Psg), which causes bacterial blight of soybean. Three toxins are known to be produced by Pss22d: syringomycin, syringopeptin and 3‐methylarginine (MeArg). In contrast to syringopeptin and syringomycin, MeArg inhibited the growth of Psg in vitro. To examine if the toxins produced by Pss22d are responsible for antagonistic effects in planta, the pathogen Psg was co‐inoculated with either Pss22d wild‐type, a syringopeptin/syringomycin‐negative double mutant (Pss22d.ΔsypA/syrE), or a MeArg‐negative mutant (Pss22d.1) into wounds of pin‐pricked leaves of greenhouse‐grown soybean plants, respectively. In all three cases, the wild‐type Pss22d and its toxin‐deficient mutants prevented development of disease symptoms normally caused by Psg. These results indicated that neither syringopeptin, nor syringomycin, nor MeArg was required for Pss22d’s antagonistic activity in planta. Consequently, factors other than the three toxins may contribute to the intra‐species antagonism in planta. 相似文献
15.
Snapdragon (Antirrhinum majus L.) is a popular ornamental and model plant species, and the recently released reference genome could greatly boost its utilization in fundamental research. However, the lack of an efficient genetic transformation system is still a major limiting factor for its full application in genetic and molecular studies. In this study, a simple method for quick regeneration and efficient Agrobacterium-mediated transformation of snapdragon was developed. Cotyledon petiole and hypocotyl explants derived from two-week-old seedlings were cultured on MS media supplemented with 2 mg/L zeatin (ZT), 0.2 mg/L 1-naphthaleneacetic acid (NAA), and 2 mg/L AgNO3, and adventitious shoots were regenerated through organogenesis with an average regeneration of 48.00% and 41.33%, respectively. By contrast, the regeneration frequency was only 22.67% for cotyledon petiole and 25.67% for hypocotyl explants in the absence of AgNO3. Moreover, the application of AgNO3 promoted indirect shoot organogenesis, while direct shoot organogenesis occurred in the absence of AgNO3 from both hypocotyl or cotyledon petiole explants. Agrobacterium-mediated genetic transformation systems were developed with this high-efficient regeneration system. The transformation efficiency has been improved from 0 to 1% through the direct shoot organogenesis to 3 to 4% via the indirect shoot organogenesis. This efficient regeneration and genetic transformation method could be important for future use of snapdragon as a model plant to address some fundamental questions which are hard to be solved by using other model plant species, and to accelerate the breeding process through CRISPR/Cas9 genome editing. 相似文献
16.
The endogenous levels of isopentenyladenine, isopentenyladenosine, zeatin and zeatin riboside and the ability for in vitro axillary shoot organogenesis and rhizogenesis were compared between mature and rejuvenated clones of Hevea brasiliensis (Müll. Arg.). Enhancement of the in vitro organogenesis ability of rubber-tree clones following somatic embryogenesis or repeated grafting onto juvenile rootstocks
was accompanied by an increase of zeatin riboside levels in shoots used as starting material for in vitro micropropagation. Furthermore, the zeatin level, in in vitro shoots of clones treated by in vitro micrografting, and consequently capable of axillary shoot and root organogenesis, was higher than in in vitro shoots of non treated mature material incapable of in vitro organogenesis. We conclude that the endogenous zeatin-like cytokinin
level (free and ribosylated forms) can be considered as a reliable marker for the recovery of in vitro shoot and root organogenesis after rejuvenating treatments in rubber-tree clones. 相似文献
17.
Polyamines are ubiquitous polycationic compounds that mediate fundamental aspects of cell growth, differentiation, and cell
death in eukaryotic and prokaryotic organisms. In plants, polyamines are implicated in a variety of growth and developmental
processes, in addition to abiotic and biotic stress responses. In the last decade, mutant studies conducted predominantly
in Arabidopsis thaliana revealed an obligatory requirement for polyamines in zygotic and somatic embryogenesis. Moreover, our appreciation for the
intricate spatial and temporal regulation of intracellular polyamine levels has advanced considerably. The exact molecular
mechanism(s) through which polyamines exert their physiological response remains somewhat enigmatic and likely serves as a
major area for future research efforts. In the following review, we discuss recent advances in the plant polyamine field,
which range from metabolism and mutant characterization to molecular genetics and potential mode(s) of polyamine action during
growth and development in vitro and in vivo. This review will also focus on the specific role of polyamines during embryogenesis and organogenesis. 相似文献
18.
A protocol for indirect differentiation of shoots / roots from leaf callus of Asiatic hybrid lily was developed through in vitro methods. The involvement of antioxidant enzymes, like, SOD, POX and CAT, and their isoenzymes during organogenesis in the morphogenetic callus was stud ied.The activity of these enzymes was increased during early development and differentiation of callus. SOD activity increased significantly as compared to POX and CAT during root formation, while it decreased in shoot formation and the decrease was significant in POX and CAT enzymes. The results indicate that the organogenesis is a very complicated biological process involving up and down regulation of a number of antioxidant enzymes, which seem to play an important role during organogenesis of Lilium callus. 相似文献
20.
An efficient and reproducible protocol for plant regeneration through in vitro culture of Indian spinach ( Beta palonga) is reported. Shoot buds were obtained both from blade petiole transition zones and midribs of fully expanded leaves. Murashige and Skoog's basal medium supplemented with naphthaleneacetic acid and benzyladenine (each at 1 mg l –1) resulted in high frequency shoot organogenesis. Histological studies showed that the origin of shoot primordia was sub epidermal. 相似文献
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