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1.
Iron nutrition affects cadmium accumulation and toxicity in rice plants 总被引:12,自引:0,他引:12
Guosheng Shao Mingxue Chen Weixia Wang Renxiang Mou Guoping Zhang 《Plant Growth Regulation》2007,53(1):33-42
The effect of iron (Fe) nutrition on cadmium (Cd) toxicity and accumulation in rice plants was studied using a hydroponic
system. The inhibitory effect of Cd on plant growth and chlorophyll content (SPAD value) was dependent on Fe level and the
genotype. Malondialdehyde (MDA) content in leaves and roots was not much affected by an increased Cd stress at 0.171 mg l−1 Fe, but it showed a rapid increase when the plants were exposed to moderate (1.89 mg l−1) and high (16.8 mg l−1) Fe levels. High Fe nutrition caused a marked reduction in Cd content in both leaves and roots. Fe content in plants was
lower at high Cd (5.0 μM) stress than at low Cd (<1.0 μM) stress. Cd stress increased both superoxide dismutase (SOD) and
peroxidase (POD) activities at low and moderate Fe levels. However, with high Fe level, it increased the POD activity, but
reduced the SOD activity. Our results substantiate the hypothesis that cell membrane-bound iron transporter (carrier) involved
in high-affinity iron transport systems can also transport Cd, and both these ions may compete for this common carrier. The
study further showed that there were significant correlations between MDA and Fe contents in leaves and roots of rice plants.
It is suggested that the occurrence of oxidative stress in plants exposed to Cd stress is mediated by Fe nutrition. The present
results also show that Cd stress affects the uptake of Cu and Zn. 相似文献
2.
《Environmental and Experimental Botany》2007,59(3):314-320
A hydroponics culture experiment was conducted to investigate the effect of iron plaque on Cd uptake by and translocation within rice seedlings grown under controlled growth chamber conditions. Rice seedlings were pre-cultivated for 43 days and then transferred to nutrient solution containing six levels of Fe (0, 10, 30, 50, 80 and 100 mg L−1) for 6 days to induce different amounts of iron plaque on the root surfaces. Seedlings were then exposed to solution containing three levels of Cd (0, 0.1 and 1.0 mg L−1) for 4 days. In order to differentiate the uptake capability of Cd by roots with or without iron plaque, root tips (white root part without iron plaque) and middle root parts (with iron plaque) of pre-cultivated seedlings treated with 0, 30 and 50 mg L−1 Fe were exposed to 109Cd for 24 h. Reddish iron plaque gradually became visible on the surface of rice roots but the visual symptoms of the iron plaque on the roots differed among treatments. In general, the reddish color of the iron plaque became darker with increasing Fe supply, and the iron plaque was more homogeneously distributed all along the roots. The Fe concentrations increased significantly with increasing Fe supply regardless of Cd additions. The Cd concentrations in dithionite–citrate–bicarbonate (DCB)-extracts and in shoots and roots were significantly affected by Cd and Fe supply in the nutrient solution. The Cd concentrations increased significantly with increasing Cd supply in the solution and were undetectable when no Cd was added. The Cd concentrations in DCB-extracts with Fe supplied tended to be higher than that at Fe0 at Cd0.1, and at Cd1.0, DCB-Cd with Fe supplied was significantly lower. Cd concentrations in roots and shoots decreased with increasing Fe supply at both Cd additions. The proportion of Cd in DCB-extracts was significantly lower than in roots or shoots. Compared to the control seedlings without Fe supply, the radioactivity of 109Cd in shoots of seedlings treated with Fe decreased when root tips were exposed to 109Cd and did not change significantly when middle parts of roots were exposed. Our results suggest that root tissue rather than iron plaque on the root surface is a barrier to Cd uptake and translocation within rice plants, and the uptake and translocation of Cd appear to be related to Fe nutritional levels in the plants. 相似文献
3.
Marta Medina Nieves Villalobos Pedro J. de la Cruz Ana Dorado Hilario Guerra 《Acta Physiologiae Plantarum》1999,21(2):141-147
The different acid invertase activity (total, soluble, wall-bound and extracellular) in calli induced on explants (cotyledon,
petiole, hypocotyl and leaf) originated from Medicago strasseri seedlings were evaluated. In cultures subjected to 16 h photoperiod, the highest total, soluble and extracellular activities
were found in calli from leaves cultured in medium 12 (MS with 0.01 mg·dm−3 (0.045 μM) of TDZ), elevated amounts of total and wall-bound invertase being found in calli induced on petioles in 12G medium
(MS with 0.01 mg·dm−3 (0.045 μM) TDZ and 3.104 mg·dm−3 glycerol). In cultures maintained in darkness, the activity detected was lower than that observed in cultures under light
conditions. The highest amounts of enzyme was bound in calli cultured on medium 12 (total and extracellular invertase) -leaves-
and medium 12D (MS with 0.001 mg·dm−3 (0.0045 μM) TDZ) (soluble invertase) -using hypocotyls. In general, the different forms of invertase activity studied seem
to appear in greatest amounts in calli induced under light conditions using leaves as explant and TDZ as growth regulator. 相似文献
4.
Effects of root and foliar applications of exogenous NO on alleviating cadmium toxicity in lettuce seedlings 总被引:3,自引:0,他引:3
The effects of sodium nitroprusside (SNP, a donor of NO) on cadmium (Cd) toxicity in lettuce seedlings were studied. SNP was added into hydroponic systems or sprayed directly on the leaves of plants grown with and without Cd. Excess supply of Cd (100 μM) caused growth inhibition, dramatically increased Cd accumulation in both leaves and roots, and inhibited the absorption of Ca, Mg, Fe and Cu. Excess Cd also decreased activities of superoxide dismutase peroxidase and catalase in leaves and roots, and increased the accumulation of superoxide anion (O 2 ·? ), hydrogen peroxide (H2O2) and malondialdehyde (MDA). Root or foliar applications of exogenous NO alleviated Cd-induced growth suppression, especially root application of 250 μM SNP and foliar addition of 500 μM SNP. Addition of SNP promoted the chlorophyll synthesis suggesting that the photosynthesis was up-regulated. Exogenous NO increased Cd-decreased activities of antioxidant enzymes and markedly diminished Cd-induced reactive oxygen species (ROS) and MDA accumulation. Moreover, the absorption of Ca, Mg, Fe and Cu was increased, indicating that exogenous NO stimulated H+-ATPase activity to promote sequestration or uptake of ions. In addition, exogenous NO also inhibited Cd transfer from roots to shoots, which may indicate that Cd retention in roots induced by NO plays a significant role in Cd tolerance in lettuce seedlings. These data suggest that under Cd stress, exogenous NO improves photosynthesis by increasing chlorophyll synthesis, protects lettuce seedlings against oxidative damage by scavenging ROS, helps to maintain the uptake of nutrient elements, and inhibits Cd transferred to shoots effectively. 相似文献
5.
Comparative study of alleviating effects of GSH, Se and Zn under combined contamination of cadmium and chromium in rice (Oryza sativa) 总被引:1,自引:0,他引:1
Fangbin Cao Nanbo Wang Mian Zhang Huaxin Dai Muhammad Dawood Guoping Zhang Feibo Wu 《Biometals》2013,26(2):297-308
A hydroponic experiment was conducted to study the ameliorative effects of separate or combined application of exogenous glutathione (GSH), selenium (Se) and zinc (Zn) upon 20 μM cadmium (Cd) plus 20 μM chromium (Cr) heavy metal stress (HM) in rice seedlings. The results showed that HM caused a marked reduction in seedling height, chlorophyll content (SPAD) and biomass, and activities of catalase (CAT) and ascorbate peroxidase (APX) in leaves and H+-ATPase in roots/leaves, but elevated superoxide dismutase (SOD) and guaiacol peroxidase (POD) activities in leaves with elevated malondialdehyde (MDA) accumulation both in leaves and roots over the control. The best mitigation effect was recorded in HM+GSH+Zn and HM+GSH (addition of GSH+Zn and GSH to HM solution), which greatly alleviated HM-induced growth inhibition and oxidative stress. Compared with HM alone, HM+GSH and HM+GSH+Zn markedly reduced Cr uptake and translocation but not affected Cd concentration; improved H+-ATPase activity and Fe, Zn, Mn uptake and translocation, and repressed MDA accumulation. Meanwhile exogenous GSH and GSH+Zn counteracted HM-induced response of antioxidant enzymes, via suppressing HM-induced dramatic increase of root/leaf SOD and leaf POD activities, and elevating stress-depressed leaf APX and leaf/root CAT activities. 相似文献
6.
7.
研究了添加外源褪黑素对水稻幼苗中Cd积累以及水稻体内Cd化学形态分布的影响.结果表明: Cd胁迫显著降低水稻幼苗地上部和根部的生物量,并且显著降低水稻叶片的叶绿素含量.适宜的外源褪黑素添加能明显提高Cd胁迫下水稻的地上部和根部生物量,降低水稻地上部和根部Cd含量.当Cd胁迫浓度为5 μmol·L-1时,添加20 μmol·L-1褪黑素使水稻地上部和根部Cd含量分别比对照处理降低48.4%和16.9%,添加100 μmol·L-1褪黑素水稻地上部和根部Cd含量分别降低67.5%和47.9%.添加外源褪黑素也显著降低了水稻体内Cd的转运效率.当Cd胁迫浓度为20 μmol·L-1时,添加20 和100 μmol·L-1褪黑素使水稻Cd的转运效率分别比对照降低24.4%和46.8%.通过逐步提取法对水稻幼苗Cd的化学结合形态进行分析发现,添加外源褪黑素使水稻体内氯化钠提取态Cd的比例提高,而水溶态Cd、乙醇提取态Cd的比例明显降低,说明添加褪黑素可促进水稻体内移动性较强的Cd形态向移动性较弱的Cd形态转移,从而降低水稻对Cd的吸收和转运. 相似文献
8.
Ascorbic acid (AsA) is the most abundant antioxidant in plants and plays a role in responding to oxidative stress. It has been shown that AsA plays a role in protecting against abiotic stresses. Rice seedlings stressed with 5 μM CdCl2 showed typical Cd toxicity (chlorosis and increase in malondialdehyde content). Rice seedlings pretreated with heat shock at 45°C (HS) or H2O2 under non-HS conditions resulted in the increase in ascorbic acid (AsA) content and the AsA/dehydroascorbate ratio in rice leaves. Exogenous application of AsA or L-galactonone-1, 4-lactone (GalL), a biosynthetic precursor of AsA, under non-HS conditions, which resulted in an increase in AsA content in leaves, enhanced subsequent Cd tolerance of rice seedlings. Pretreatment with imidazole, an inhibitor of NADPH oxidase, under HS conditions significantly decreased H2O2 and AsA contents in leaves and reduced subsequent Cd tolerance of rice seedlings. We also observed that pretreatment with lycorine, which is known to inhibit the conversion of GalL to AsA, significantly inhibited HS-induced AsA accumulation in leaves and reduced HS-induced protection against subsequent Cd stress of rice stress. It appears that HS- or H2O2-induced protection against subsequent Cd stress of rice seedlings is mediated through AsA. The time-course analyses of HS in rice seedlings demonstrated that the accumulation of H2O2 preceded the increase in AsA. Based on the data obtained in this study, it could be concluded that the early accumulation of H2O2 during HS signals the increase in AsA content, which in turn protects rice seedlings from oxidative damage caused by Cd. 相似文献
9.
We studied how the relationship between cadmium (Cd) toxicity and oxidative stress influenced the growth, photosynthetic efficiency,
lipid peroxidation, and activity of ntioxidative enzymes in the roots and leaves of rice(Oryza sativa L Dongjin). Plants were exposed to Cd for 21 d. Both seedling growth and photosynthetic efficiency decreased gradually with
increasing cadmium concentrations. Lipid peroxidation increased slowly in both roots and leaves, causing oxidative stress.
However, each tissue type responded differently to Cd concentrations with regard to the induction/ inhibition of antioxidative
enzymes. The activity of Superoxide dismutase (SOD) increased in both roots and leaves. Ascorbate peroxidase (APX) activity
increased in leaves treated with up to 0.25 μM Cd, then decreased gradually at higher concentrations. In contrast, APX activity
in roots increased and remained constant between 0.25 and 25 μM Cd. Enhanced peroxidase (POD) activity was recorded for treatments
with up to 25/M Cd, gradually decreasing at higher concentrations in the leaves but remaining unchanged in the roots. Catalase (CAT) activity
increased in the roots, but decreased in the leaves, whereas the activity of glutathione reductase (GR) was enhanced in both
roots and leaves, where it remained elevated at higher Cd concentrations. These results suggest that rice seedlings tend to
cope with free radicals generated by Cd through coordinated, enhanced activities of the antioxidative enzymes involved in
detoxification. 相似文献
10.
The effects of Cu, Cd, and Pb toxicity on photosynthesis in cucumber leaves (Cucumis sativus L.) were studied by the measurements of gas exchange characteristics, chlorophyll (Chl) fluorescence parameters, and Chl content. Concentrations of metals in sequence of 20 μM Cu, 20 and 50 μM Cd, and 1 000 μM Pb decreased the plant dry mass to 50–60 % after 10 d of treatment whereas 50 μM of Cu decreased it to 30 %. The content of Cd in leaves of plants treated with 50 μM Cd was three times higher than the contents of Cu and Pb after plant treatment with 50 μM Cu or 1 000 μM Pb. Hence Cd was transported to leaves much better than Cu and Pb. Nevertheless, the net photosynthetic rate and stomatal conductance in leaves treated with 50 μM Cu or Cd were similarly reduced. Thus, Cu was more toxic than Cd and Pb for photosynthesis in cucumber leaves. None of the investigated metals decreased internal CO2 concentrations. Also the effect of metals on potential efficiency of photosystem 2, PS2 (Fv/Fm) was negligible. The metal dependent reduction of PS2 quantum efficiency (ΦPS2) after plant adaptation in actinic irradiation was more noticeable. This could imply that reduced demand for ATP and NADPH in a dark phase of photosynthesis caused a down-regulation of PS2 photochemistry. Furthermore, in leaves of metal-treated plants the decrease in water percentage as well as lower contents of Chl and Fe were observed. Thus photosynthesis is not the main limiting factor for cucumber growth under Cu, Cd, or Pb stress. 相似文献
11.
Effects of silicon nutrition on cadmium uptake, growth and photosynthesis of rice plants exposed to low-level cadmium 总被引:3,自引:0,他引:3
The effect of silicon (Si) nutrition on low-level cadmium (Cd) toxicity symptoms was investigated in hydroponically-grown rice seedlings (Oryza sativa L.). Silicon (0.0, 0.2, or 0.6 mM) was added when seedlings were 6 or 20 days old representing early (SiE) or late (SiL) Si treatment, respectively. Cadmium (0.0 or 2.5 μM) was added when seedlings were 6 days old. Measurements included generation of CO2 and light response curves; chlorophyll fluorescence analysis; growth; and tissue-element content analysis. Our results showed that low-level Cd treatment generally inhibited growth and photosynthesis. However, the addition of 0.2 or 0.6 mM SiE or SiL significantly reduced root- and leaf-Cd content. Consequently, the addition of 0.6 mM SiL significantly alleviated low-level Cd-induced inhibition of growth. Furthermore, 0.2 mM Si treatment significantly reduced g s compared to 0.0 or 0.6 mM Si without inhibiting A, especially in +Cd plants, suggesting an increase in instantaneous water-use-efficiency (IWUE). Additionally, in +Cd plants, the addition of 0.6 mM SiE significantly reduced F o but increased F v/F m, while treatment with 0.2 mM SiL significantly increased qP, suggesting an increase in light-use-efficiency. We thus, propose that 0.6 mM SiL treatment is required for the alleviation of low-level Cd-mediated growth inhibition. Furthermore, we suggest that 0.2 mM Si concentration might be close to the optimum requirement for maximum Si-induced increase in IWUE in rice plants, especially when under low-level Cd-stress. Our results also suggest that Si alleviates low-level Cd toxicity by improving light-use-efficiency. 相似文献
12.
Rice (Oryza sativa L.) seedlings stressed with CdCl2 (0.5 mM or 50 μM) showed typical Cd toxicity (leaf chlorosis, decrease in chlorophyll content, or increase in H2O2 and malondialdehyde contents). Rice seedlings pretreated with heat shock at 45°C (HS) for 2 or 3 h were protected against
subsequent Cd stress. Rice seedlings pretreated with HS had similar Cd concentration in leaves caused by CdCl2 as those non-HS. The content of H2O2 increased in leaves 1 h after HS exposure. However, APX and GR activities were higher in HS-treated leaves than their respective
control, and it occurred after 2 h of HS treatment. Pretreatment of rice seedlings with H2O2 under non-HS conditions resulted in an increase in APX, GR, and CAT activities and protected rice seedlings from subsequent
Cd stress. HS-induced H2O2 production and protection against subsequent Cd stress can be counteracted by imidazole, an inhibitor of NADPH oxidase complex.
Results of the present study suggest that early accumulation of H2O2 during HS signals the increase in APX and GR activities, which in turn prevents rice seedlings from Cd-caused oxidative damage. 相似文献
13.
Cadmium (Cd) toxicity of rice (Oryza sativa L. cv. Taichung Native 1) seedlings was evaluated by the decrease in chlorophyll content and the increase in malondialdehyde (MDA) in the second leaves of rice seedlings. CdCl2 (5 μM) treatment was accompanied by a decrease in the contents of ascorbic acid (AsA) and AsA + dehydroascorbate (DHA) and in the ratios of AsA/DHA in leaves. However, CdCl2 treatment resulted in an increase in DHA content in leaves. Moreover, the decrease in AsA content was prior to the occurrence of chlorosis and associated with the increase in MDA content in the leaves of seedlings treated with Cd. Pretreatment with 0.5 mM AsA or l-galactono-1,4-lactone (GalL), the biosynthetic precursor of AsA, for 6 h resulted in an increase in the contents of AsA and reduced glutathione (GSH), the ratios of AsA/DHA and GSH/oxidized glutathione, and the activities of ascorbate peroxidase (APX) and glutathione reductase (GR) in the leaves of rice seedlings. Quantitative RT-PCR was applied to quantify the mRNA levels for OsAPX and OsGR genes from rice leaves to examine the effect of AsA or GalL pretreatment on the expression of OsAPX and OsGR genes in rice leaves. The expression of OsAPX2, OsAPX3, OsAPX4, OsAPX5, OsAPX6, OsAPX7, and OsGR1 was increased by AsA or GalL pretreatment. Rice seedlings pretreated with AsA or GalL were observed to reduce the subsequent Cd-induced toxicity. Our results suggest that AsA content may play a role in regulating Cd toxicity of rice seedlings. 相似文献
14.
Effect of nitrogen deficiency on antioxidant status and Cd toxicity in rice seedlings 总被引:1,自引:0,他引:1
Effect of nitrogen (N) deficiency on antioxidant status and Cd toxicity in rice seedlings was investigated. N deficiency resulted
in a reduction of shoot growth but not root growth. The contents of N-containing compounds such as nitrate, chlorophyll, and
protein decreased in leaves of rice seedlings grown under N deficiency. Accumulation of abscisic acid and H2O2 in leaves was induced by N deficiency. The content of ascorbate and the activities of ascorbate peroxidase, glutathione reductase,
and catalase in N-deficient leaves were lower than their respective control leaves. However, glutathione content was not affected
and superoxide dismutase activity was increased by N deficiency. Cd toxicity in N-deficient seedlings was more pronounced
than that in N-sufficient ones. Pretreatment with ascorbate or L-galactono-1,4-lactone, a biosynthetic precursor of ascorbate
resulted in a reduction of Cd toxicity enhanced by N deficiency. N deficiency also resulted in an enhancement of Cd uptake
in rice seedlings. The possible mechanism of Cd toxicity enhanced by N deficiency is discussed. 相似文献
15.
Toxicity in leaves of rice exposed to cadmium is due to hydrogen peroxide accumulation 总被引:4,自引:0,他引:4
The production of H2O2 in detached rice leaves of Taichung Native 1 (TN1) caused by CdCl2 was investigated. CdCl2 treatment resulted in H2O2 production in detached rice leaves. Diphenyleneiodonium chloride (DPI) and imidazole (IMD), inhibitors of NADPH oxidase (NOX),
prevented CdCl2-induced H2O2 production, suggesting that NOX is a H2O2-genearating enzyme in CdCl2-treated detached rice leaves. Phosphatidylinositol 3-kinase inhibitors wortmanin (WM) or LY294002 (LY) inhibited CdCl2-inducted H2O2 production in detached rice leaves. Exogenous H2O2 reversed the inhibitory effect of WM or LY, suggesting that phosphatidylinositol 3-phosphate is required for Cd-induced H2O2 production in detached rice leaves. Nitric oxide donor sodium nitroprusside (SNP) was also effective in reducing CdCl2-inducing accumulation of H2O2 in detached rice leaves. Cd toxicity was judged by the decrease in chlorophyll content. The results indicated that DPI, IMD,
WM, LY, and SNP were able to reduce Cd-induced toxicity of detached rice leaves. Twelve-day-old TN1 and Tainung 67 (TNG67)
rice seedlings were treated with or without CdCl2. In terms of Cd toxicity (leaf chlorosis), it was observed that rice seedlings of cultivar TN1 are Cd-sensitive and those
of cultivar TNG67 are Cd-tolerant. On treatment with CdCl2, H2O2 accumulated in the leaves of TN1 seedlings but not in the leaves of TNG67. Prior exposure of TN1 seedlings to 45oC for 3 h resulted in a reduction of H2O2 accumulation, as well as Cd tolerance of TN1 seedlings treated with CdCl2. The results strongly suggest that Cd toxicity of detached leaves and leaves attached to rice seedlings are due to H2O2 accumulation. 相似文献
16.
Accumulation of ammonium ion in cadmium tolerant and sensitive cultivars of Oryza sativa 总被引:1,自引:0,他引:1
Cd-tolerant and Cd-sensitive rice cultivars were used to study the role of NH4
+ accumulation in Cd-induced toxicity. NH4
+ accumulation seems to be involved in regulating the toxicity of rice seedlings caused by CdCl2. This conclusion was based on the observations that (a) on treatment with CdCl2, NH4
+ content increased rapidly in the leaves of the Cd-sensitive cultivar (cv. Taichung Native 1, TN1) but not in the Cd-tolerant cultivar (cv. Tainumg 67, TNG67), (b) pretreatment with abscisic acid (ABA) enhanced Cd tolerance and reduced Cd-induced NH4
+ accumulation in TN1 seedlings, (c) exogenous application of the ABA biosynthesis inhibitor, fluridone, decreased Cd tolerance and increased NH4
+ content in leaves of TNG67, (d) exogenous application of phosphinothricin, an inhibitor of glutamine synthetase (GS), which resulted in NH4
+ accumulation in the leaves, also induced toxicity similar to Cd in TN1 seedlings. Evidence is presented to show that Cd-induced NH4
+ accumulation in TN1 leaves is attributable to a decrease in GS activity. Since Cd-treated TN1 leaves had higher glutamine and glutamate contents than control leaves, it is unlikely that glutamine (or glutamate) depletion is the mechanism which regulates Cd-induced toxicity. 相似文献
17.
Iron plaque formation and its effect on arsenic uptake by different genotypes of paddy rice 总被引:2,自引:0,他引:2
Background and aims
Iron plaque on roots has been hypothesized to be an effective restraint on the uptake of arsenic (As) by rice plants. Evaluating the formation of iron plaque and its effect on As uptake by various rice cultivars is valuable because selecting low As uptake rice cultivars results in reduced risks associated with rice consumption. This study examines iron plaque formation and its effect on As uptake by different genotypes of rice cultivars.Methods
Hydroponic cultures were conducted in phytotron at day 25/night 20°C and the rice seedlings in fifth-leaf age were treated with Fe (II) at the levels of 0 and 100 mg L?1 in the Kimura B nutrient solutions for 14 days. The amount of iron plaque formation of 28 rice cultivars was determined by using the DCB extractable Fe of roots. Four cultivars representing high and low iron plaque formation capability, from indica and japonica respectively, were selected out of the 28 cultivars and processed for Fe and As treatments. After Fe treatments for 4 days, the seedlings were fed with As (III) at levels of 0, 0.5, and 1 mg L?1 for another 10 days. We were thus able to determine the amounts of iron plaque formation and the As content in iron plaque, roots, and shoots of the four tested cultivars.Results
Iron plaque formation capability differed among tested twenty-eight rice cultivars. Feeding As to four tested cultivars enhanced iron plaque formation on roots; the As uptake by roots and shoots was decreased by the addition of Fe. Both the retention of As on iron plaque and the decrease of As uptake by the addition of Fe varied among tested cultivars and were not correlated with the iron plaque formation capability.Conclusions
Iron plaque can sequestrate As on the roots and reduce rice’s As uptake. However, other factors also influence the As uptake, namely the differences in binding affinity of iron plaque to As, the existent As species in the rhizosphere, and the uptake capability of various As species by rice plants. These factors should also be considered when selecting low As uptake rice cultivars. 相似文献18.
R. V. Sreedhar L. Venkatachalam R. Thimmaraju N. Bhagyalakshmi M. S. Narayan G. A. Ravishankar 《Biologia Plantarum》2008,52(2):355-360
Shoot buds were induced directly on either side of midrib from adaxial surface of immature leaf explants in Stevia rebaudiana Bertoni five weeks after culturing in Murashige and Skoog’s nutrient medium supplemented with 8.88 μM of N
6-benzylaminopurine and kinetin ranging from 4.65 to 6.98 μM. Immature leaves of 0.6 to 1 cm were found to produce best response
(93 %) with a highest number of 4.93 shoot buds per explant. For elongation of regenerated shoot buds, MS medium supplemented
with 30 g dm−3 sucrose and indole-3-butyric acid (IBA) ranging from 4.92 to 7.38 μM were found most suitable. The medium was further modified
to suit bioreactor cultivation of regenerated shoots wherein the use of two-fold MS salts and 60 g dm−3 sucrose resulted in a high biomass yield of 50.68 g dm−3 (m/v) accounting for about 590 micro-cuttings in three weeks. Best rooting of micro-cuttings occurred in half strength MS
medium supplemented with IBA ranging from 4.92 to 7.38 μM, 15 g dm−3 sucrose and gelled with 0.8 % agar. Rooted plants were successfully established in substrate containing sand, Vermicompost and garden soil in equal proportions and grown in greenhouse. This is the first report on direct shoot regeneration from
Stevia leaves. 相似文献
19.
In the present study, in vitro regeneration system for a recalcitrant woody tree legume, Leucaena leucocephala (cvs. K-8, K-29, K-68 and K-850) from mature tree derived nodal explants as well as seedling derived cotyledonary node explants
was developed. Best shoot initiation and elongation was found on full-strength Murashige and Skoog (MS) medium supplemented
with 3 % (m/v) sucrose, 100 mg dm−3 myoinositol, 100 mg dm−3 glutamine, 20.9 μM N
6-benzylamino-purine (BAP) and 5.37 μM 1-naphthalene acetic acid (NAA). Rooting was induced in half-strength MS medium containing
2 % (m/v) sucrose, 100 mg dm−3 myoinositol, 14.76 μM indole-3-butyric acid (IBA) and 0.23 μM kinetin. The cultivar K-29 gave the best response under in vitro conditions. Rooted plantlets were subjected to hardening and successfully transferred to greenhouse. Further, somatic embryogenesis
from nodal explants of cv. K-29 via an intermittent callus phase was also established. Pronounced callusing was observed on full-strength MS medium containing
3 % (m/v) sucrose, 100 mg dm−3 myoinositol, 40.28 μM NAA and 12.24 μM BAP. These calli were transferred to induction medium and maximum number of globular
shaped somatic embryos was achieved in full-strength MS medium fortified with 3 % (m/v) sucrose, 100 mg dm−3 myoinositol, 15.0 μM 2,4-dichlorophenoxyacetic acid (2,4-D), 5.0 μM BAP and 1.0 mM proline. Moreover, an increase in endogenous
proline content up to 28th day of culture in induction medium was observed. These globular shaped somatic embryos matured in full-strength MS medium
with 3 % (m/v) sucrose, 100 mg dm−3 myoinositol, 10.0 μM BAP, 2.5 to 5.0 μM IBA and 0.5 mM spermidine. 相似文献
20.
Wen-Tao Yang Hang Zhou Jiao-Feng Gu Pei-Qin Peng Qin-Ru Zeng 《Soil & Sediment Contamination》2017,26(1):70-83
The objectives of the present study were to investigate the mitigation of lead (Pb), cadmium (Cd), and arsenic (As) in a multi-metal contaminated soil and their accumulation in rice plants (Oryza sativa L., cv II You 93) using a combined amendment (CMF, calcium carbonate + metakaolin + fused calcium–magnesium phosphate fertilizer). The results showed that application of CMF was effective in reducing the acid-extractable concentrations of soil Pb and Cd. The exchangeable concentrations of soil As showed an initial decrease followed by a gradual increase. The application of 0.2% CMF notably reduced the concentrations of Pb, Cd, and As in brown rice by 46.5%, 43.6%, and 32.0%, respectively. The concentration of As in brown rice was 0.179 mg kg?1 at 0.2% CMF, which met the maximum levels of contaminants in foods of China (MLs) (the ML of Pb, Cd, and As is 0.2 mg kg?1 according to the China national standard GB 2762-2012). At 1.6% CMF, the concentrations of Pb and Cd in brown rice were 0.002 and 0.185 mg kg?1, respectively, i.e., reductions of 99.6% and 74.1%, and these values also fell within the MLs. 相似文献