共查询到20条相似文献,搜索用时 15 毫秒
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Zhiyong Pan Shiping Zhu Rui Guan Xiuxin Deng 《Plant Cell, Tissue and Organ Culture》2010,103(2):145-153
The compound 2,4-Dicholorophenoxyacetic acid (2,4-D) is an important growth regulator which is used in the majority of embryogenic
cell and tissue culture systems. However, 2,4-D also appears to have a negative effect on growth and development of plant
tissues and organs cultured in vitro. For example, 2,4-D exerts inhibition on in vitro somatic embryo initiation and/or development
of most citrus species. To understand the molecular mechanism by which 2,4-D inhibits somatic embryogenesis (SE), proteomic
changes of Valencia sweet orange (Citrus sinensis) embryogenic callus induced by treatments with a high concentration of 2,4-D (6 mg l−1) was investigated. Nine 2,4-D-responsive proteins were identified, of which eight were up-regulated and one was down-regulated.
Interestingly, three of the eight up-regulated proteins were osmotic stress-associated, suggesting that 2,4-D induced osmotic
stress in Valencia embryogenic callus. This speculation was supported by results from our physiological studies: 2,4-D treated
callus cells exhibited increased cytoplasm concentration with a significant reduction in relative water content (RWC) and
an obvious increase in levels of two osmolytes (proline and soluble sugar). Taken together, our results suggested that 2,4-D
could inhibit somatic embryo initiation by, at least in part, inducing osmotic stress to citrus callus cells. 相似文献
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Robert Konieczny Maria Pilarska Monika Tuleja Terezia Salaj Tomasz Ilnicki 《Plant Cell, Tissue and Organ Culture》2010,100(2):123-130
This study developed a plant regeneration protocol for Trifolium nigrescens (Viv.) via somatic embryogenesis (SE). Immature zygotic embryos at torpedo (TsE) and cotyledonary (CsE) stage were cultured on media with different auxins and cytokinins at different concentrations. The cultural requirements for SE differed between the explants used: the addition of 6-furfurylaminopurine (kinetin) or N6-[2-isopentenyl]-adenine (2iP) along with 2,4-dihydrophenoxyacetic acid (2,4-D) or 1-naphthaleneacetic acid (NAA) was needed to elicit the embryogenic response of CsE, but an exogenous cytokinin totally inhibited 2,4-D-induced SE from TsE. When applied alone, neither the cytokinin nor NAA induced SE in TsE or CsE. In all effective cultures the first somatic embryos appeared directly from the upper part of the hypocotyl (TsE and CsE) and from the margin of cotyledons (TsE) on day 7. Embryogenic callus occurred on CsE after 10 days. At comparable concentrations 2,4-D was a more potent SE inducer than NAA, but most of the embryoids induced on media with 2,4-D displayed morphological abnormalities, whereas those produced in the presence of NAA generally resembled zygotic embryos. Plant regeneration was achieved after transfer of somatic embryos or embryo-derived first shoots to medium without plant growth regulators (PGRs). The frequency of plant recovery was about 30% for embryoids obtained on media containing 2,4-D, and for material from media with NAA the recovery rates were 44–68% (somatic embryos) and 72–100% (embryoid-derived shoots). Regenerants appeared identical to each other and to wild plants; they produced flowers and had the chromosome complement typical for the species, 2n = 16, in root tip cells. 相似文献
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Hugo P. F. Fraga Leila N. Vieira Clarissa A. Caprestano Douglas A. Steinmacher Gustavo A. Micke Daniel A. Spudeit Rosete Pescador Miguel P. Guerra 《Plant cell reports》2012,31(12):2165-2176
DNA methylation is an epigenetic regulatory mechanism of gene expression which can be associated with developmental phases and in vitro morphogenetic competence in plants. The present work evaluated the effects of 5-azacytidine (AzaC) and 2,4-dichlorophenoxyacetic acid (2,4-D) on Acca sellowiana somatic embryogenesis (SE) and global DNA methylation levels by high-performance liquid chromatography mass spectrometry (HPLC/MS/MS). 2,4-D-free treatments revealed no somatic embryo formation in both accessions tested. Treatments supplemented with 2,4-D pulse plus AzaC in the culture medium resulted in increased embryo formation. In AzaC-free treatment, HPLC/MS/MS analysis showed a gradual increase in methylation levels in cultures of both accessions tested during SE induction. Treatment with AzaC and 2,4-D-free resulted in a marked decrease in methylation for both accessions, ranging from 37.6 to 20.8?%. In treatment with 2,4-D and AzaC combined, the 85 accession showed increasing global methylation levels. Otherwise, the 101X458 accession, in the same treatment, showed a decrease between 10 and 20?days, followed by an increase after 30?days (39.5, 36.2 and 41.6?%). These results indicate that 2,4-D pulse combined with AzaC improves SE induction. However, the conversion phase showed that although positively influencing SE induction, AzaC had a dysregulatory effect on the stage of autotrophic plant formation, resulting in significantly lower conversion rates. The results suggest that DNA methylation dramatically influences SE in Acca sellowiana, and global DNA methylation dynamics are related to morphogenetic response. Key message 5-Azacytidine combined with 2,4-D increases the number of Acca sellowiana somatic embryos. Global DNA methylation is directly affected by these compounds. 相似文献
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There is a growing need to characterize the effects of environmental stressors at the molecular level on model organisms with the ever increasing number and variety of anthropogenic chemical pollutants. The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D), as one of the most widely applied pesticides in the world, is one such example. This herbicide is known to have non-targeted undesirable effects on humans, animals and soil microbes, but specific molecular targets at sublethal levels are unknown. In this study, we have used Rhizobium leguminosarum bv. viciae 3841 (Rlv) as a nitrogen fixing, beneficial model soil organism to characterize the effects of 2,4-D. Using metabolomics and advanced microscopy we determined specific target pathways in the Rlv metabolic network and consequent changes to its phenotype, surface ultrastructure, and physical properties during sublethal 2,4-D exposure. Auxin and 2,4-D, its structural analogue, showed common morphological changes in vitro which were similar to bacteroids isolated from plant nodules, implying that these changes are related to bacteroid differentiation required for nitrogen fixation. Rlv showed remarkable adaptation capabilities in response to the herbicide, with changes to integral pathways of cellular metabolism and the potential to assimilate 2,4-D with consequent changes to its physical and structural properties. This study identifies biomarkers of 2,4-D in Rlv and offers valuable insights into the mode-of-action of 2,4-D in soil bacteria. 相似文献
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Zhigang Ju Wei Sun Xiangyu Meng Lingjie Liang Yueqing Li Tongtong Zhou Huan Shen Xiang Gao Li Wang 《Plant Cell, Tissue and Organ Culture》2018,132(1):99-110
Kelussia odoratissima Mozaff. (or Kelus) is a medicinal plant native to the Zagros Mountains in Iran. This plant is widely used as a food flavoring and for its health-promoting properties. It has been considered an endangered species by the United Nations Development Programme. In this study, a somatic embryogenesis (SE) method was developed for mass propagation of Kelus. The green globular embryogenic callus was induced on cotyledonary leaves using the Murashige and Skoog (MS) medium supplemented with 1 mg/l 2,4-dichlorophenoxyaceticacid (2,4-D) and 0.25 mg/l Kinetin. Different treatments were assayed for proliferation of the embryogenic callus. The calli remained embryogenic in an MS medium containing 2,4-D (1 mg/l). The light treatments and carbon source showed significant effects (P?≤?0.05) on the proliferation and development of somatic embryos. These treatments improved the conversion rate of the cotyledonary-stage embryos by 100%. The average numbers of embryos in the globular, heart, torpedo, and cotyledonary stages decreased by the addition of 3 g/l case in hydrolisate. The genetic stability among tissue culture-derived plants and the mother plant were assessed using the amplification fragment length polymorphism. No polymorphic band was observed among all the plants, exhibiting the genetic stability during in vitro multiplication. This research provides a promising approach for true-to-type plant multiplication of K. odoratissima through SE. 相似文献
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Takahata K Takeuchi M Fujita M Azuma J Kamada H Sato F 《Plant & cell physiology》2004,45(11):1658-1668
Somatic embryogenesis is a unique process in plant cells. For example, embryogenic cells (EC) of carrot (Daucus carota) maintained in a medium containing 2,4-dichlorophenoxyacetic acid (2,4-D) regenerate whole plants via somatic embryogenesis after the depletion of 2,4-D. Although some genes such as C-ABI3 and C-LEC1 have been found to be involved in somatic embryogenesis, the critical molecular and cellular mechanisms for somatic embryogenesis are unknown. To characterize the early mechanism in the induction of somatic embryogenesis, we isolated genes expressed during the early stage of somatic embryogenesis after 2,4-D depletion. Subtractive hybridization screening and subsequent RNA gel blot analysis suggested a candidate gene, Carrot Early Somatic Embryogenesis 1 (C-ESE1). C-ESE1 encodes a protein that has agglutinin and S-locus-glycoprotein domains and its expression is highly specific to primordial cells of somatic embryo. Transgenic carrot cells with reduced expression of C-ESE1 had wide intercellular space and decreased polysaccharides on the cell surface and showed delayed development in somatic embryogenesis. The importance of cell-to-cell attachment in somatic embryogenesis is discussed. 相似文献
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Somatic embryogenesis in <Emphasis Type="Italic">Solanum tuberosum</Emphasis> L.: a histological examination of key developmental stages 总被引:4,自引:0,他引:4
A potential novel method of producing high-quality potato (Solanum tuberosum L.) nuclear seeds is through the process of somatic embryogenesis (SE). Somatic embryo formation has been successfully reported in many plant species, but in potato, reliable SE systems are still at the experimental stage. A key factor in the success of any SE system is the ability to discriminate SE-specific cellular structures from those emerging through an organogenic route. In the investigation reported here we attempted to discriminate the progression of specific stages of potato SE by histological means. Internodal segment (INS) explants from 4- to 6-week-old cv. Desiree in vitro cultures were successively cultured on SE induction (for 2 weeks) and expression/regeneration media (for 3 weeks) with and without 2,4-dichlorophenoxyacetic acid (5 M). Microscopic examination of histological slides prepared using INS explants at different stages revealed the presence of characteristic globular, heart and torpedo stages in the potato SE system along with other associated unique features such as protoderm development and discrete vascular connections. These results confirm the occurrence of potato SE as per the accepted definition of the term.Abbreviations 2,4-D 2,4-Dichlorophenoxyacetic acid - ELS Embryo-like structure(s) - INS Internodal segment(s) - PEM Proembryo mass - SE Somatic embryogenesis 相似文献
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Correlation between Plant Growth Regulator Release Rate and Bioactivity for the Series of Newly Synthesized Phytoactive Polymers 总被引:1,自引:0,他引:1
Michael I. Shtilman Manolis N. Tzatzarakis Potvakan S. Voskanyan Ioannis N. Tsakiris Andreas K. Tsakalof Aristidis M. Tsatsakis 《Journal of Plant Growth Regulation》2006,25(3):211-218
Phytoactive polymers are high molecular weight systems in which a plant growth regulator (PGR) unit is attached to the polymeric
chain by a hydrolyzable chemical bond. The release rate of the PGR is linked to the biological activity of the phytoactive
polymer and can be controlled by properties inherent in the whole macromolecular system. In this study the correlation of
biological activity and plant growth regulator hydrolytic release rate was investigated for the series of newly synthesized
2,4-dichlorophenoxyacetic acid (2,4-D) polymeric esters. The polymers synthesized differ in their molecular weight, side group
structure, and 2,4-D residue content. The influence of these polymer characteristics on the 2,4-D hydrolytic release was investigated,
and it was demonstrated that hydrolysis rate substantially depends on the polymer molecular weight, side group structure,
and 2,4-D residue content. It was also demonstrated that phytoactive polymer bioactivity depends on the hydrolysis rate of
the polymers, and in dependence of this parameter can provide stimulating or inhibiting activity. Biological activity was
illustrated by the elongation of wheat and barley coleoptiles. 相似文献
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The chemical 2,4-dichlorophenoxyacetic acid (2,4-D) regulates plant growth and development and mimics auxins in exhibiting
a biphasic mode of action. Although gene regulation in response to the natural auxin indole acetic acid (IAA) has been examined,
the molecular mode of action of 2,4-D is poorly understood. Data from biochemical studies, (Grossmann (2000) Mode of action
of auxin herbicides: a new ending to a long, drawn out story. Trends Plant Sci 5:506–508) proposed that at high concentrations,
auxins and auxinic herbicides induced the plant hormones ethylene and abscisic acid (ABA), leading to inhibited plant growth
and senescence. Further, in a recent gene expression study (Raghavan et al. (2005) Effect of herbicidal application of 2,4-dichlorophenoxyacetic
acid in Arabidopsis. Funct Integr Genomics 5:4–17), we have confirmed that at high concentrations, 2,4-D induced the expression
of the gene NCED1, which encodes 9-cis-epoxycarotenoid dioxygenase, a key regulatory enzyme of ABA biosynthesis. To understand the concentration-dependent mode
of action of 2,4-D, we further examined the regulation of whole genome of Arabidopsis in response to a range of 2,4-D concentrations
from 0.001 to 1.0 mM, using the ATH1-121501 Arabidopsis whole genome microarray developed by Affymetrix. Results of this study
indicated that 2,4-D induced the expression of auxin-response genes (IAA1, IAA13, IAA19) at both auxinic and herbicidal levels of application, whereas the TIR1 and ASK1 genes, which are associated with ubiquitin-mediated auxin signalling, were down-regulated in response to low concentrations
of 2,4-D application. It was also observed that in response to low concentrations of 2,4-D, ethylene biosynthesis was induced,
as suggested by the up-regulation of genes encoding 1-aminocyclopropane-1-carboxylic acid (ACC) synthase and ACC oxidase.
Although genes involved in ethylene biosynthesis were not regulated in response to 0.1 and 1.0 mM 2,4-D, ethylene signalling
was induced as indicated by the down-regulation of CTR1 and ERS, both of which play a key role in the ethylene signalling pathway. In response to 1.0 mM 2,4-D, both ABA biosynthesis and
signalling were induced, in contrast to the response to lower concentrations of 2,4-D where ABA biosynthesis was suppressed.
We present a comprehensive model indicating a molecular mode of action for 2,4-D in Arabidopsis and the effects of this growth
regulator on the auxin, ethylene and abscisic acid pathways.
Experiment station: Plant Biotechnology Centre, Primary Industries Research Victoria, Department of Primary Industries, La
Trobe University, Bundoora, Victoria 3086, and the Victorian Microarray Technology Consortium (VMTC). 相似文献
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A gain-of-function mutation in the Arabidopsis pleiotropic drug resistance transporter PDR9 confers resistance to auxinic herbicides 下载免费PDF全文
Arabidopsis (Arabidopsis thaliana) contains 15 genes encoding members of the pleiotropic drug resistance (PDR) family of ATP-binding cassette transporters. These proteins have been speculated to be involved in the detoxification of xenobiotics, however, little experimental support of this hypothesis has been obtained to date. Here we report our characterization of the Arabidopsis PDR9 gene. We isolated a semidominant, gain-of-function mutant, designated pdr9-1, that exhibits increased tolerance to the auxinic herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). Reciprocally, loss-of-function mutations in PDR9 confer 2,4-D hypersensitivity. This altered auxin sensitivity defect of pdr9 mutants is specific for 2,4-D and closely related compounds as these mutants respond normally to the endogenous auxins indole-3-acetic acid and indole-butyric acid. We demonstrate that 2,4-D, but not indole-3-acetic acid transport is affected by mutations in pdr9, suggesting that the PDR9 transporter specifically effluxes 2,4-D out of plant cells without affecting endogenous auxin transport. The semidominant pdr9-1 mutation affects an extremely highly conserved domain present in all known plant PDR transporters. The single amino acid change results in increased PDR9 abundance and provides a novel approach for elucidating the function of plant PDR proteins. 相似文献
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The possible effects of synthetic auxins and anti-auxins onthe metabolism of indole-3-acetic acid (IAA) in plant tissueshave not been properly studied in the past. For this reasonseedlings of peas, beans, and sunflower have been treated withthe synthetic auxin, 2,4-dichlorophenoxyacetic acid (2,4-D)and two supposed anti-auxins, 2,3,5-tri-iodobenzoic acid (TIBA)and maleic hydrazide (MH), at non-toxic levels sufficient tocause well-marked growth responses. Estimates of the contentof alcohol-extractable growth-substances have subsequently beendetermined, after separation by paper partition chromatography.Although at least six active natural compounds have been indicatedin such extracts, only the effects of treatment on IAA levelshave been followed in detail. 2,4-D treatment of both leaves and roots has no detectable effecton the levels of free endogenous IAA, and it is thereby concludedthat 2,4-D is an auxin in its own right and does not act ongrowth via a disturbance of IAA metabolism. There are indicationsthat considerable amounts of the absorbed 2,4-D are convertedin plant tissues to a neutral detoxication product which iseasily decomposed to liberate 2,4-D during chromatographic analysis. TIBA treatment of pea roots dramatically reduces their freeendogenous IAA content, in some cases to 1/10,000 the normallevel. The implications of these findings are discussed in termsof the physiological and morphological responses of plants toTIBA treatment. There are indications that MH may put up slightly the levelof free endogenous auxin in pea roots but further confirmatorywork is required. 相似文献
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Małgorzata D. Gaj Aneta Trojanowska Agnieszka Ujczak Martyna Mędrek Aleksandra Kozioł Beata Garbaciak 《Plant Growth Regulation》2006,49(2-3):183-197
Plant hormones are considered to be the key factors involved in triggering in vitro induced plant morphogenesis, including somatic embryogenesis (SE). Mutants affected in SE and altered in hormonal response therefore provide valuable material for genetic research on in vitro induced plant embryogenesis. The capacity for SE was studied in 27 mutants with defects in response to different plant hormones: auxin, ABA, gibberellin and cytokinin, and evaluated in 2-week-old mutant and wild-type cultures in terms of their efficiency and productivity. SE was induced in vitro via a direct morphogenic pathway, through the culture of immature zygotic embryos on standard solid medium with 5 μM 2,4-D. The majority of the analyzed mutants displayed a significantly impaired capacity for SE; and those affected belonged to several different hormone-defective groups, including forms affected in auxin (axr4), gibberellin (ga) and ABA (abi, hyl1, cpb20, abh1) response. These mutants showed a significant decrease in embryogenic response as manifested by a low efficiency and/or productivity of SE. Additionally, SE efficiency was analyzed for axr4-1 mutant on media supplemented with different auxins while GA3 and inhibitors of gibberellins (uniconazol P and paclobutrazol), were applied for pkl1-1-mutant. The selected mutants provide a valuable research tool for studying the molecular mechanisms determining the induction of embryogenesis in cultures of somatic tissues. Their usefulness in further studies is discussed. 相似文献
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Summary
Cupressus macrocarpa and C. arizonica were examined for callus and cell culture production in vitro. Both species produced callus on agar-solidified MSCY medium supplemented with vitamins, antioxidants, 0.14 μM kinetin (KIN), and 10 μM 2,4-dichlorophenoxyacetic acid (2,4-D). Suspension cultures of both species were established in liquid MSCY medium. Seiridin
(SE) and iso-seiridin (ISE), two phytotoxic butenolides produced by Seiridium cardinale, S. cupressi, and S. unicorne, the causal agents of many canker diseases of cypress, were tested on callus or cell suspension cultures. In the medium without
other plant growth regulators (PGR), SE promoted cell proliferation of cypress better than ISE, for callus initiation, callus
maintenance, and cell suspension cultures. The growth rates of cypress callus tissues and suspension cultures of both cypress
species on media containing 50–150 μM SE or ISE were measured. At concentrations of 50 μM and higher, growth rates increased exponentially with the SE concentration. A comparison with KIN and 2,4-D indicated that
50 μM SE promoted growth of callus tissues and cell suspension cultures more than 100 μM ISE. SE can also interact with, or counteract, KIN and 2,4-D. It was demonstrated that SE could replace KIN in the medium
for C. arizonica. SE could be involved in cell enlargement and proliferation processes. The less susceptible cypress species (C. arizonica) had a high content of terpenoids than that of the more susceptible species (C. macrocarpa). SE could be a useful tool as a phytohormonal-like regulator to manipulate physiological changes at the cellular level and
as an elicitor of sensitivity or tolerance of cypress germplasm to the phytotoxin. 相似文献
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K. Balaraju S. Saravanan P. Agastian S. Ignacimuthu 《Acta Physiologiae Plantarum》2011,33(4):1123-1133
An improved method of direct somatic embryogenesis (SE) was developed in Swertia chirata for the first time using leaves and roots of in vitro-grown young seedlings. In the present study, 2,4-dichlorophenoxyacetic
acid (2,4-D) was assessed individually and in combination with other auxins, as well as with cytokinin for its effectiveness
to induce somatic embryos. Leaf explants with abaxial side in the medium produced maximum number of somatic embryos. This
system omits the callus stage and thus reduces the process of SE in S. chirata by 35–45 days. Embryos at different stages of development were observed. Maturation of heart stage embryos were observed
on Murashige and Skoog (MS) medium containing 1 mg L−1 2,4-D. Upon transfer to the germination medium, they were converted to cotyledonary stage and then plantlets of 33% and 68%
of them were converted to cotyledonary stage and then plantlets on MS medium supplemented with 0.05 and 0.1 mg L-1 GA3 respectively. The 2,4-D alone at 1.0 or 1.5 mg L−1 was found to be better for embryogenic tissue initiation than 2,4-D in combination with indole-3-acetic acid or α-naphthalene
acetic acid. For further embryo development, 2,4-D was combined with cytokinins such as 6-benzylaminopurine (BAP) and kinetin
or plant growth regulator free medium or medium with 50% reduced concentration of the same hormone while subculturing. Mean
germination and percentage of survival were maximum in the medium containing 1.0 mg L−1 2,4-D in combination with 0.1 mg L−1 BAP. Regenerated plantlets were morphologically and genetically identical. This method offers a vast scope for the clonal
propagation of endangered plants. 相似文献
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Hosek P Kubes M Lanková M Dobrev PI Klíma P Kohoutová M Petrásek J Hoyerová K Jirina M Zazímalová E 《Journal of experimental botany》2012,63(10):3815-3827
The molecular basis of cellular auxin transport is still not fully understood. Although a number of carriers have been identified and proved to be involved in auxin transport, their regulation and possible activity of as yet unknown transporters remain unclear. Nevertheless, using single-cell-based systems it is possible to track the course of auxin accumulation inside cells and to specify and quantify some auxin transport parameters. The synthetic auxins 2,4-dichlorophenoxyacetic acid (2,4-D) and naphthalene-1-acetic acid (NAA) are generally considered to be suitable tools for auxin transport studies because they are transported specifically via either auxin influx or efflux carriers, respectively. Our results indicate that NAA can be metabolized rapidly in tobacco BY-2 cells. The predominant metabolite has been identified as NAA glucosyl ester and it is shown that all NAA metabolites were retained inside the cells. This implies that the transport efficiency of auxin efflux transporters is higher than previously assumed. By contrast, the metabolism of 2,4-D remained fairly weak. Moreover, using data on the accumulation of 2,4-D measured in the presence of auxin transport inhibitors, it is shown that 2,4-D is also transported by efflux carriers. These results suggest that 2,4-D is a promising tool for determining both auxin influx and efflux activities. Based on the accumulation data, a mathematical model of 2,4-D transport at a single-cell level is proposed. Optimization of the model provides estimates of crucial transport parameters and, together with its validation by successfully predicting the course of 2,4-D accumulation, it confirms the consistency of the present concept of cellular auxin transport. 相似文献