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1.
The effects of 2,4-dichlorophenoxyacetic acid (2,4-D) concentration, length of induction period and light quality on leaf regeneration of quince clone BA 29 were investigated. After 2, 4 or 6 days of induction with 2.5 mg l−1 or 5.0 mg l−1 2,4-D, leaves were cultured under red, blue, red+blue, far-red+blue, white, far-red light or darkness conditions. Leaves thereby treated showed different responses, with respect to somatic embryogenesis, callus, red-nodular structures or roots. Callus production increased with increasing 2,4-D concentration and induction period, although it was not influenced by light quality; the only exception was far-red+blue light, which reduced callusing response. This result suggested involvement of the blue-absorbing photoreceptor system in the callus formation processes. A high regeneration of red-nodular structures with a meristematic appearance was also observed; from some histological characterizations, we presumed they were adventitious buds that were arrested at an early developmental stage. Red-nodular structures increased with decreasing 2,4-D concentration and induction period. In the regeneration of such structures, the blue-absorbing photoreceptor system appeared to have a negative effect but only at a low photoequilibrium value. In contrast, light quality which activated phytochrome induced an increment in regeneration, but the response did not vary for photoequilibrium values ranging from 0.43 to 0.86. For root regeneration, phytochrome seemed to be the only photoreceptor involved. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   

2.
The effect of varying light regimes on in vitro rooting of microcuttings of two pear (Pyrus communis L.) cultivars was investigated. Cultures of the easy to-root Conference and the difficult-to-root Doyenne d'Hiver were incubated for 21 days with or without indole-3-butyric acid (IBA) in the medium in darkness or under continuous far-red (8 µmol m–2 s–1), blue, white or red (15 or 36 µmol m–2 s–1) light. Conference rooted without IBA when exposed to red, blue or white light while no rooting was observed under far-red light and in darkness. The high rooting efficiency under red and, by contrast, the inhibition under far-red light and darkness suggest the involvement of the phytochrome system in rhizogenesis. The addition of IBA to the culture medium enhanced root production under all light regimes in both cultivars. Red light, especially at the lower photon fluence rate, had a positive effect by increasing root extension (number × length of roots) and stimulating secondary root formation.Abbreviations IBA Indole-3-butyric acid - R red light - B blue light - FR far-red light - W white light - D darkness - Pfr active (far-red light absorbing) form of phytochrome - Ptot total phytochrome - BA benzyl-adenine  相似文献   

3.
Various parameters of the Tanada effect (Proc. Natl. Acad. Sci. U.S. 59: 376–380. 1968) have been defined. This phenomenon, in which root tips of Phaseolus aureus L. adhere to a negatively charged glass surface when they are irradiated with 660 nm (red) light and release under 730 nm (far-red) light, has been characterized as follows. Secondary roots, whether etiolated or light grown exhibit photoreversible adhesion. Primary roots do not. Tips from 6–8 mm secondary roots exhibit the best response to red light, whereas tips from 3 mm roots respond best to far-red light. Red light saturetes the adhesion system at about 50 μ W/cm2xnm and far-red light, release system at about 150 ü W/cm2 xnm. The adhesion effect begins to show escape from far-red reversibility within 60–90 seconds, an observation quite different from other “typical” long term de- etiolation effects. In addition, root tips irradiated with red light begin to release spontaneously in the dark after 10 min, and have nearly completed release after 50 min. Tips irradiated with continuous red light show gradual release after 15 minutes of exposure. Whether these data indicate an extremely rapid dark reversion of Pfr to Pr or decay of Pfr under continuous red light is not known at this time. In order to study tip adhesion and release, the glass beaker surface may be negatively charged with thiocyanate (SCN-), nitrate (NO3-), sulfate (SO42-), chloride (Cl-), phosphate (PO43-), citrate (C6H5O73-), oxalate (C2O42-) or glutamine (C5H8NO4-). Benzoate (C7H5O2-) and acetate (CH3COO-) were found to be relatively ineffective for red light adhesion, however when citrate and oxalate were used release was inhibited. This was apparently due to a chelation of Ca2+since release began immediately as excess Ca+2 was added to the bathing solution. Substitution of GTP, ITP, UTP, or CTP for ATP resulted in only 20 to 40% adhesion and release for GTP, ITP and UTP, CTP showed normal adhesion kinetics under red light but very slow release kinetics under far-red light. The effects of red and far-red light in the numbers of secondary roots are that red light inhibits root initiation while far-red light partially reverses the red light effect.  相似文献   

4.
Hydrogen peroxide (H2O2), an active oxygen species, is widely generated in many biological systems and mediates various physiological and biochemical processes in plants. In this study we demonstrated that the exogenous H2O2 was able to promote the formation and development of adventitious roots in mung bean seedlings. Treatments with 1–100 mM H2O2 for 8–18 h significantly induced the formation and development of adventitious roots. Catalase (CAT) and ascorbic acid, which are H2O2 scavengers or inhibitors, eliminated the adventitious root-promoting effects of exogenous H2O2. H2O2 may have a downstream signaling function in the auxin signaling pathway and be involved in auxin-induced adventitious root formation. 2,3,5-Triiodobenzoic acid (TIBA), an inhibitor of auxin polar transport, strongly inhibited adventitious rooting of mung bean seedlings; however, the inhibiting effects of TIBA on adventitious rooting can be partially reversed by the exogenous IBA or H2O2. Diphenylene iodonium (DPI) strongly inhibits the activity of NADPH oxidase, which is one of the main sources of H2O2 formation in plant cells. DPI treatment strongly inhibited the formation of adventitious roots in mung bean, but the inhibitory effects of DPI on rooting can be partially reversed by the exogenous H2O2 or IBA. This indicates that the formation of adventitious roots was blocked once the generation of H2O2 through NADPH oxidase was inhibited, and H2O2 mediated the IBA-induced adventitious root formation. Furthermore, a rapid increase in the endogenous level of H2O2 was detected during incubation with water 12–36 h after the primary root removal in mung bean seedlings. Three hours after the primary root removal, the generation of endogenous H2O2 was markedly induced in IBA-treated seedlings in comparison with water-treated seedlings. This implies that IBA induced overproduction of H2O2 in mung bean seedlings, and that IBA promoted adventitious root formation via a pathway involving H2O2. Results obtained suggest that H2O2 may function as a signaling molecule involved in the formation and development of adventitious roots in mung bean seedlings.  相似文献   

5.
Effects of auxins (IAA, IBA and NAA) on K. humboldtiana root culture cultivated in 16-h photoperiod or in dark have been observed. Light affected positively the production of biomass when cultivated on medium supplemented with NAA in 10 and 25 mol –1 concentrations. In the presence of IAA and IBA these values were significantly lower. The growth dynamics of root cultures depended on the auxin used. The best adventitious roots elongation and lateral roots induction on media supplemented with IBA has been ascertained. Morphological and anatomical differences in dependence on auxin used were observed. NAA supported the formation of huge callus-like mass besides mostly very short roots, especially under the light. Similarly IAA induced short roots, and IBA seems to be the most effective substance for the root elongation in this model system. NAA induced roots with larger diameter under the light compared with the other two auxins used. The reason is in the different anatomical structure of roots which was characterized by higher number of cell layers and large intercellulars in the cortex. The shape of cortical cells in the presence of IBA depended on the light conditions. Isodiametric cortical cells were present in roots cultivated in 16-h photoperiod, irregularly-shaped cells in the dark. The effect of light conditions was the smallest in the case of roots grown on IAA enriched media.  相似文献   

6.
Galactoglucomannan oligosaccharides (GGMOs) activity in K. humboldtiana root culture has been determined. GGMOs inhibited adventitious root growth and lateral root induction in contrast to IAA, IBA, and NAA stimulating effect in these processes. Similarly, the combination of GGMOs with natural auxins (IAA, IBA) evoked an inhibition of adventitious root growth and lateral root induction that depended on the oligosaccharides concentration and the type of auxin. The growth stimulating effect of the synthetic auxin, NAA, in adventitious roots was negatively affected by GGMOs, but they were without influence on lateral root induction. The presence of oligosaccharides triggered lateral root position on adventitious roots and the anatomy of adventitious roots (diameter, proportion of primary cortex to the central cylinder, number and size of primary cortical cells, intercellular spaces, and the number of starch grains in cells of primary cortex) in dependence on their coactions with auxin.  相似文献   

7.
Our previous results have demonstrated that both nitric oxide (NO) and hydrogen peroxide (H2O2) are involved in the promotion of adventitious root development in marigold (Tagetes erecta L.). However, not much is known about the intricate molecular network of adventitious root development triggered by NO and H2O2. In this study, the involvement of calcium (Ca2+) and calmodulin (CaM) in NO- and H2O2-induced adventitious rooting in marigold was investigated. Exogenous Ca2+ was capable of promoting adventitious rooting, with a maximal biological response at 50 μM CaCl2. Ca2+ chelators and CaM antagonists prevented NO- and H2O2-induced adventitious rooting, indicating that both endogenous Ca2+ and CaM may play crucial roles in the adventitious rooting induced by NO and H2O2. NO and H2O2 treatments increased the endogenous content of Ca2+ and CaM, suggesting that NO and H2O2 enhanced adventitious rooting by stimulating the endogenous Ca2+ and CaM levels. Moreover, treatment with Ca2+ enhanced the endogenous levels of NO and H2O2. Additionally, Ca2+ might be involved as an upstream signaling molecule for CaM during NO- and H2O2-induced rooting. Altogether, the results suggest that both Ca2+ and CaM are two downstream signaling molecules in adventitious rooting induced by NO and H2O2.  相似文献   

8.
Summary The effect of indole-3-butyric acid (IBA) and 1-naphthaleneacetic acid (NAA) on lateral root formation was investigated in adventitious root culture of Panax ginseng. Lateral root formation was affected by IBA (24.6 μM) or NAA (9.8 μM). Lateral root primordia emerged from the explant root pericycle after about 7 d of culture when the roots were cultured on Schenk and Hildebrandt (SH) medium supplemented with 24.6 μM IBA or 9.8 μM NAA. However, no changes were observed in the explant root pericycle on auxin-free medium. The IBA treatment was more effective for lateral root induction and root growth compared to NAA. In morphological and histological aspects, the lateral roots formed under IBA treatment developed normally, while NAA-treated roots exhibited abnormal growth. The accumulation of total saponin was greater in roots treated with IBA than with NAA.  相似文献   

9.
Leaf, cotyledon, and hypocotyl explants were obtained from 3-week-old seedlings of open-pollinated ‘Golden Delicious’ (Malus domestica bork H.) grown in vitro. They were placed on modified Murashige and Skoog (MS) medium containing B5 vitamins, sucrose and agar, supplemented with 6-benzylaminopurine (BAP) and α-naphthaleneacetic acid (NAA), and maintained at 25°C±2 in the light or in the dark to assess morphogenetic responses. Leaf and cotyledon explants cultured in the dark for an initial 3 weeks, then transferred to light for 4 weeks, produced 5- to 20-fold more adventitious shoots than those cultured for 7 weeks in the light. Conversely, light did not significantly influence the number of adventitious shoots formed on hypocotyl explants. Five-minute daily exposures of leaf explants to red light (651 nm) suppressed adventitious shoot formation by 80%; five-minute exposure to far-red light (729 nm) immediately following the red light counteracted the red suppression. Seedling explants, immature fruit halves and immature embryos were also cultured on Schenk and Hildebrandt (SH) medium containing 2, 4-dichlorophenoxyacetic acid (2, 4-D), p-chlorophenoxyacetic acid (CPA) and kinetin. Light inhibited callus formation on leaf and cotyledon explants, but not on hypocotyl explants. The derived callus was placed on MS + BAP or MS + BAP + NAA for shoot regeneration. Both shoots and roots regenerated from callus placed in the dark but not in the light; the frequency of shoot regeneration was 5% or less. Regenerated shoots were rooted on MS macronutrient salts (1/3 concentration), micronutrients, i-inositol, thiamine HCl, sucrose and agar with or without indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), or NAA under a light intensity of 5.0 W.m-2 (16 h per day). Auxin concentration strongly influenced root morphology.  相似文献   

10.
Hydrogen peroxide (H2O2), an active oxygen species, is widely generated in many biological systems and mediates various physiological and biochemical processes in plants. In the present study, we present a signaling network involving H2O2, nitric oxide (NO), calcium (Ca2+), cyclic guanosine monophosphate (cGMP), and the mitogen-activated protein kinase (MAPK) cascade during adventitious rooting in mung bean seedlings. Both exogenous H2O2 and the NO donor sodium nitroprussiate were capable of promoting the formation and development of adventitious roots. H2O2 and NO signaling pathways were elicited in parallel in auxin-induced adventitious rooting. Cytosolic Ca2+ was required for adventitious rooting, and Ca2+ served as a downstream component of H2O2, as well as cGMP or MAPK, signaling cascades. cGMP and MAPK cascades function downstream of H2O2 signaling and depend on auxin responses in adventitious root signaling processes.  相似文献   

11.
Günter Ruyters 《Planta》1988,174(3):422-425
Starch breakdown and respiratory O2 uptake in the green algaDunaliella tertiolecta (Butcher) are stimulated not only by blue, but also by red light. In the present study, attempts are described to identify the photoreceptor(s) involved. Fluence rate-response curves with different slopes in the ultraviolet (UV)/blue and in the red spectral region as well as differences in the kinetics and in the unfluence of dark pre-incubation on the stimulation of respiratory O2 uptake by blue and red light strongly indicate the action of two photoreceptors. Since the effect of red light shows some far-red reversibility, and since simultaneous irradiation with red and far-red light decreases the effectiveness of red light, the involvement of phytochrome — in addition to the UV/blue photoreceptor(s) — is suggested in the light-stimulated respiration inDunaliella.Abbreviation UV ultraviolet  相似文献   

12.
Gynura procumbens is a medicinal plant used in South East Asia to treat various ailments such as rash, hemorrhoids, inflammation, and diabetes. In order to develop a large-scale culture system for G. procumbens biomass containing bioactive compounds, adventitious root cultures were initiated from leaf explants. Murashige and Skoog (MS) media containing different compositions of indole-3-butyric acid (IBA), 1-naphthalene-acetic acid (NAA), and combinations of both plant growth regulators (PGRs) were evaluated for root induction. A combination of 3 mg/l NAA + 1 mg/l IBA gave the highest root induction (48%) as compared to other PGRs treatments after 9 weeks of incubation period. Subsequently, the adventitious roots were established in liquid culture containing MS medium and the combination of 3 mg/l NAA + 1 mg/l IBA. A study on the medium strength, sucrose concentration, pH, and light versus dark was conducted to optimize the in vitro culture conditions. The results showed that differences in MS medium strength from half to double strength, and light or dark condition did not significantly affect the biomass production, while the initial medium pH of 5.5 and 2% w/v sucrose concentration were most suitable for the root culture growth. Nuclear magnetic resonance (NMR) spectroscopy was performed to characterize the metabolite content in the root cultures of G. procumbens. Among the elucidated metabolites were some phenylpropanoids identified as caffeic acid, chlorogenic acid, and 3,5-di-O-caffeoylquinic acid which might be the bioactive compounds associated to the folk use of this plant.  相似文献   

13.
Abscisic acid (ABA) and hydrogen peroxide (H2O2) are important regulatory factors involved in plant development under adversity stress. Here, the involvement of H2O2 in ABA-induced adventitious root formation in cucumber (Cucumis sativus L.) under drought stress was determined. The results indicated that exogenous ABA or H2O2 promoted adventitious rooting under drought stress, with a maximal biological response at 0.5 μM ABA or 800 μM H2O2. The promotive effects of ABA-induced adventitious rooting under drought stress were suppressed by CAT or DPI, suggesting that endogenous H2O2 might be involved in ABA-induced adventitious rooting. ABA increased relative water content (RWC), leaf chlorophyll content, chlorophyll fluorescence parameters (Fv/Fm, ΦPS II and qP), water soluble carbohydrate (WSC) and soluble protein content, and peroxidase (POD), polyphenol oxidase (PPO) and indoleacetate oxidase (IAAO) activities, while decreasing transpiration rate. However, the effects of ABA were inhibited by H2O2 scavenger CAT. Therefore, H2O2 may be involved in ABA-induced adventitious root development under drought stress by stimulating water and chlorophyll content, chlorophyll fluorescence, carbohydrate and nitrogen content, as well as some enzyme activities.  相似文献   

14.
The post-embryonic growth of the Arabidopsis thaliana root system can be modified by different types of stress, such as sublethal concentrations of metals, which may induce the production of reactive oxygen species (ROS). In this study, the effects of different concentrations of potassium chromate (KCrO4) on the distribution and relative quantity of hydrogen peroxide (H2O2) were determined in primary and adventitious roots in A. thaliana HyPer line seedlings. This line has a biosensor that specifically reports H2O2 levels within tissues as fluorescence. Primary root growth was inhibited at 100 μM Cr (VI); in contrast, adventitious root formation was induced over the main root growth axis. These structures proliferated from 100-160 μM Cr (VI), and much higher concentrations (180-200 μM) of KCrO4 were required to affect their growth. The H2O2 distributions were observed in the columella and lateral root cap of primary roots of plants grown in medium lacking dichromate, but following the development of toxicity symptoms, H2O2 changed its distribution to the meristem and differentiation zones. Conversely, adventitious roots had comparable H2O2 distribution patterns in untreated plants and those exposed to Cr (VI) supplementation. Thus, differential H2O2 distribution correlates with the resistance of adventitious roots, but not primary roots, to dichromate and underlies cell reorganization at the apex to support growth.  相似文献   

15.
Low-energy blue light (450, 475 nm) has been found to induced unfolding of etiolated barley leaves (Hordeum rulgare cv. Ingrid). This induction can be reversed by far-red light. Barley leaf unfolding is normally stimulated by red light, reversed by far-red light, and can be considered to be a typical phytochrome controlled response. It is possible to explain the effects by red and blue light as mediated by the same photoreceptor. The phototransformation of this pigment results in two forms, P2 and P4, to which physiological activity can be ascribed. The red and blue light affect different steps in a cyclical photoconversion. Calculated theoretical dose response curves are presented for such a model in agreement with the experimental data.  相似文献   

16.
Previous studies have shown that hydrogen peroxide (H2O2) may mediate the auxin response during the formation of adventitious roots (AR). However, the mechanism and distribution of H2O2 during AR formation remains unclear. In this study, we investigate the spatiotemporal changes and role of H2O2 in AR initiation and development. Application of 5?C100 mM H2O2 to Mung bean (Phaseolus radiatus L.) hypocotyl cuttings induced AR formation in a dose-dependent manner. The effect was blocked by ascorbic acid (AA), an important reducing substrate for H2O2 reduction. Depletion of endogenous H2O2 by AA resulted in the significant reduction of AR emergence, suggesting a physiological role for H2O2 in the regulation of AR formation. Determination of H2O2 content showed that the level of H2O2 increased gradually and reached the highest value 60 h after induction of AR. Further detection of endogenous H2O2 by the specific fluorescent probe dichlorofluorescein diacetate (H2DCF-DA) and 3,3??-diaminobenzidine (DAB) staining in transverse sections of the basal region of cuttings revealed that obvious H2O2 signals were observed in the pericycle cells between the vascular bundles 24 h after the primary roots were removed. With the development of root primordia, H2O2 signals increased gradually and were mainly distributed in the root meristem. AA significant inhibited the H2O2-dependent fluorescence and the formation of AR, suggesting an essential role of H2O2 generation during AR initiation and development. Furthermore, the involvement of Ca2+ during H2O2-mediated AR formation was evaluated. Ca2+ channel inhibitors LaCl3 and ruthenium red (RR) and Ca2+ chelator ethylene glycol-bis(2-aminoethylether)-N,N,N??,N??-tetraacetic acid (EGTA) prevent H2O2-induced AR formation, which indicate that the hypocotyl cuttings response to H2O2 depends on the availability of both intracellular and extracellular Ca2+ pools, and Ca2+ is a downstream messenger in the signaling pathway triggered by H2O2 to promote adventitious root formation.  相似文献   

17.
Periploca sepium adventitious roots were cultured on 0.5 Murashige and Skoog solid media supplemented with exogenous hormones of different types and various concentrations, and with sucrose of different concentrations. Auxins (indole butyric acid (IBA) and naphthalene acetic acid (NAA)) and cytokinins (6-benzylaminopurine (BA) and kinetin (KT)) were selected as exogenous hormones for adventitious root proliferation. Compared with other hormones, IBA was the suitable auxin for adventitious root proliferation. Under this circumstance, every root explant generates 10?C15 adventitious roots (1- to 2-cm long) after 30?days. However, nothing but callus was induced on the root explants when NAA was added into the medium and the same result was achieved when auxins (IBA or NAA) were added into the media together with cytokinins (BA or KT). The suitable concentration of IBA for adventitious root proliferation was 1?C2?mg/l, when every root explant generated 10?C20 adventitious roots (1- to 2-cm long). The optimum concentration of IBA for periplocin accumulation was 1?mg/l, when the periplocin content reached 95.46???g/g. With regard to the investigation of sucrose concentration, 2?C3% (w/v) sucrose was favorable for adventitious root proliferation as every root explant in this concentration generated 10?C20 adventitious roots (1- to 2-cm long). The highest periplocin content (101.56???g/g) was achieved at 5% (w/v) sucrose, whereas the periplocin content at 5% (w/v) sucrose did not show significant difference from the periplocin content (95.38 and 98.47???g/g, respectively) at 3% (w/v) or 4% (w/v) sucrose.  相似文献   

18.
Arabidopsis thaliana (L.) Heynh. race Columbia plants were grown in red. blue, red + far-red, blue + far-red and various light mixtures of red + blue + far-red light under 14 h light/10 h dark photoperiods. Each single light source and light mixture maintained a constant irradiance (50 μmol m−2 s−1) and the mixtures of red + blue + far-red maintained a constant ratio of red/far-red light, but varied in the ratio of blue to red + far-red light. Depending on the method used for calculation, values of the fraction of phytochrome in the far-red absorbing form (Pfr/Ptot) for these light mixtures were either constant or decreased slightly with increasing percentage of blue light in the mixtures. Arabidopsis flowered early (20 days) in blue, blue + far-red and red + far-red light and late (55 days) in red light. In mixtures of red + blue + far-red light, each of which established a nearly constant Pfr/Ptot flowering was in direct relation to time and irradiance level of blue light. Leaf area and petiole length were also correlated with blue light irradiance levels.  相似文献   

19.
以荷兰进口甜椒的子叶和下胚轴为外植体,接种到附加不同植物生长调节剂的培养基上,筛选出MS+6-BA 4.0 mg/L+NAA 0.1 mg/L为子叶和下胚轴最佳不定芽分化培养基;MS+IBA 0.2 mg/L和MS+IBA 0.5 mg/L为最佳不定根分化培养基。  相似文献   

20.
An attempt was made to induce rooting from single node cuttings of Camellia sinensis var. TV-20 under controlled conditions and study its biochemical changes during rooting. The nodal cuttings were pretreated with different concentrations of IAA, NAA and IBA and kept in a growth chamber (25 ±2 °C, 16 h photoperiod (55 μ mol m−2 s−1) with cool, white fluorescent lamps and 65% relative humidity) for 12 h. Among the three auxins used for pretreatment, IBA showed more positive response on rooting as compared to IAA and NAA within 2 weeks of transfer to potting medium. Among four concentrations of IBA tested, 75 ppm gave maximum percentage of rooting, number of roots and root length. Therefore, IBA was used further in experiments for biochemical investigation. The adventitious rooting was obtained in three distinct phases i.e. induction (0–12 days), initiation (12–14 days) and expression (14–18 days). IAA-oxidase activity of IBA-treated cuttings increased slightly as compared to control. The activity was found to decrease during induction and initiation phases and increase during expression phase. The peroxidase activity in IBA-treated cuttings increased up to initiation phase and declined at the expression phase. Polyphenoloxidase activity increased both in IBA-treated and control cuttings during induction and initiation phase but declined slowly during expression phase. Total phenolic content was higher in IBA-treated cuttings, particularly in initiation and expression phases and it also correlated with peroxidase activity. Phenolics might be playing key role for induction of adventitious rooting, and phenolic compounds can be used as rooting enhancer in tea plant.  相似文献   

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