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1.
水稻突变体对镉的吸收及其亚细胞分布和化学形态特点   总被引：12，自引：0，他引：12  
Wild-type （Zhonghua 11） and mutant rice （Oryza sativa L.） plants were used to investigate the effect of cadmium （Cd） application on biomass production, to characterize the influx of Cd from roots to shoots, and to determine the form, content, and subcellular distribution of Cd in the roots, leaf sheaths, and leaves of the rice plants. Seedlings were cultivated in a nutrient solution and were treated with 0.5 mmol L^-1 of Cd^2＋ for 14 d. The sensitivity of rice plants to Cd toxicity was tested by studying the changes in biomass production and by observing the onset of toxicity symptoms in the plants. Both the wild-type and mutant rice plants developed symptoms of Cd stress. In addition, Cd application significantly （P ≤ 0.01） decreased dry matter production of roots, leaf sheaths, and leaves of both types, especially the mutant. The Cd content in roots of the mutant was significantly （P ≤0.05） higher than that of the wild-type rice. However, there was no significant difference in the Cd content of roots, leaf sheaths, and leaves between the wild-type and mutant rice. Most of the Cd was bound to the cell wall of the roots, leaf sheaths, and leaves, and the mutant had greater Cd content in cell organelles than the wild type. The uneven subcellular distribution could be responsible for the Cd sensitivity of the mutant rice. Furthermore, different chemical forms of Cd were found to occur in the roots, leaf sheaths, and leaves of both types of rice plants. Ethanol-, water-, and NaCl-extractable Cd had greater toxicity than the other forms of Cd and induced stunted growth and chlorosis in the plants. The high Cd content of the toxic forms of Cd in the cell organelles could seriously damage the cells and the metabolic processes in mutant rice plants.  相似文献   

2.
‘Lvbao-701’ is a cultivar of Chinese flowering cabbage(Brassica parachinensis) that exhibits low cadmium(Cd) accumulation and high Cd tolerance.In this study, this cultivar was compared with a high-Cd accumulating cultivar, ‘Chixin-4’, to characterize the mechanisms influencing Cd accumulation in B. parachinensis. Root cell walls were isolated by dissolving the cytoplasm with an organic solvent, and root Cd and phytochelatin(PC) contents were analyzed. In addition, a PC synthase gene fragment was cloned and expressed under Cd stress conditions. The proportions of Cd bound to root cell walls were higher in the ‘Lvbao-701’ plants(68.32%–76.80%) than in the ‘Chixin-4’ plants(35.36%–54.18%) after exposure to Cd stress. The proportions of Cd bound to root cell walls measured using cell walls isolated with a non-destructive method were higher than those obtained using a conventional method that required grinding and centrifugation. Exposure to Cd stress induced the PC production and resulted in higher PC contents in the ‘Lvbao-701’ plants than in the ‘Chixin-4’ plants. Cloning and expression analysis of a B. parachinensis PC synthase cDNA fragment indicated that PC synthase gene expression was induced by Cd and occurred mainly in the roots of both ‘Lvbao-701’ and ‘Chixin-4’ plants. However, the PC synthase gene expression level was higher in the‘Lvbao-701’ roots than in the ‘Chixin-4’ roots. Therefore, a higher abundance of Cd in the root cell walls of ‘Lvbao-701’ and up-regulated PC production in the roots are probably the main reasons why ‘Lvbao-701’ exhibits lower Cd translocation to the shoots and higher tolerance to Cd than ‘Chixin-4’.  相似文献   

3.
Corn and wheat plants were grown in a nutrient culture solution at four levels of phosphorus (0,0.12,0.60 and 3.0mmol L^-1) and two levels of cadmium(0 and 4.0umol L^-1) in greenhouse for a 18-day period.The concentrations of phosphorus and cadmium in cell wall,cytoplasm and vacuoles of roots and leaves were examined by cell fractionation techniques.With increasing phosphorus in medium,the contents of P in cell wall,cytoplasm and vacuoles of corn and wheat roots and leaves increased.The highest content of P was observed in cell wall,next in vacuoles,and the lowest in cytoplasm.The wheat subcellular fractions in both roots and leaves hab higher concentrations of phosphorus than those of corn.Increasing phosphorus in medium significantly inhibited the intracellular Cd accumulation in both species,However,at P concentration up to 3.0mmol L^-1,the Cd content in cell wall was increased.Increasing phosphorus resulted in reduction of the subcellular Cd content in cell wall was increased.Increasing phosphorus resulted in reduction of the subcellualr Cd content in corn and wheat leaves.Compared with corn,the wheat roots had a higher Cd content in the cell wall and vacuoles and a lower in cytoplasm,while in leaf subcellular fractions the wheat cell had a higher Cd content in its vacuoles and a lower one in its cytoplasm,The results indicate that phosphorus may be involved in sequestration of Cd ionic activity in both cell wall and vaculoes by forming insoluble Cd phosphate.  相似文献   

4.
To elucidate the mechanisms of tolerance to zinc (Zn) deficiency and Zn toxicity in the root of apple trees, the apple rootstock Malus hupehensis (Pamp.) Rehd seedlings were selected to study the responses of organic acids to Zn homeostasis in roots under low Zn (0 μmol L-1 ), adequate Zn (as control, 4 μmol L-1 ) and toxic Zn (100 μmol L-1 ) treatments. The differences of Zn concentrations and accumulations in the roots were highest, compared with those in the stems and leaves, when apple seedlings were subjected to low and toxic Zn treatments for 1 d. The concentrations and accumulations of oxalic and malic acids in the roots in the low and toxic Zn treatments increased by 20% to 60% compared with those of the control treatment. Significantly negative correlations were found between the total Zn concentrations and the concentrations of oxalic and malic acids in the roots under 1 d of low Zn treatment. However, contrary correlations were found for the toxic Zn treatment. Meanwhile, the maximum influx rates of Zn 2+ under low and toxic Zn treatments increased by 30% and 20%, respectively, compared with the rate of the control treatment. Both Zn deficiency and Zn toxicity increased the concentrations of organic acids in root after short-time Zn treatment, which could resist Zn stress through balanding Zn homeostasis in M. hupehensis Rehd.  相似文献   

5.
A experiment was carried to evaluate the effects of Al on growth,accumulations of free proline and amino acid in 2 wheat cultivars(Triticum aestivum L.),Yangmai No.5 and Jian 864,differing in Al Sensitivity.Plants grew initially in a nutrient solution without Al for 13 days before the addition of Al and finally in a nutrient solution containing 0.5mmol Al(L^-1)for 19 days,the results showed that there were marked deceases in dry weight,relative growth rate(RGR) and net assimilation rate (NAR)of Al-treated seedlings compared with control plants.The Al effects were more evident in Yangmai No.5 than Jian 864.Leaf area ratio(LAR) was little affected by Al.RGR was highly correlated with NAR rather than LAR.Aluminum increased the concentrations of free proline and total free amino acid in shoots of both the cultivars.The increases were greater in Yangmai No.5 than in Jian 864.The percentage of free proline in total amino acid in shoots was not affected by Al treatment.It was possible that accumulation of proline was merely a symptom of Al injury.The concentrations of total nitrogen in Al-treated plants did not significantly differ from those of control plants.Nitrate reductase activity(NRA),in leaves was severely decreased by Al,and a greater decrease was noted in Yangmai No.5 than in Jian 864,but NRA in roots of both the cultivars was not affected.The decreases in NRA might be and indirect(accumulation of amino acid) rather than a direct result of Al toxicity.  相似文献   

6.
A number of higher plants are able to hyperaccumulate cadmium(Cd). However, it is unknown whether cadmium(Cd) plays a biological functional role in the carbonic anhydrase(CA) of hyperaccumulators. A hydroponic experiment was conducted to explore the potentially physiological function of Cd in CA and the accumulation and tolerance of Cd in the Zn/Cd hyperaccumulator Picris divaricata Vant. P. divaricata was exposed to nutrient solutions with six Cd concentrations(0, 5, 10, 25, 50 and 75 μmol L~(-1)). After 12 d, plants were harvested for the analysis of plant biomass, Cd concentration and CA activity. The Cd concentrations in plant increased with the increasing Cd in nutrient solution, reaching 640 and 3 100 mg kg~(-1) in shoot and root, respectively, at the 75 μmol L~(-1) Cd treatment. Meanwhile, plant growth was enhanced by the Cd treatments at 5–25 μmol L~(-1), but it was significantly inhibited when the plants were exposed to solutions with higher Cd concerntrations(50 and 75 μmol L~(-1)). Exposure to Cd significantly increased the CA activity in P. divaricata, which reached a maximum value of 21.27 U mg~(-1) proteins at the 25 μmol L~(-1)Cd treatment, and the CA activity and shoot Cd concentration were positively correlated at solutions Cd of ≤ 25 μmol L~(-1). Moreover, two protein bands appeared on the denatured gel electrophoresis of purified CA, indicating that P. divaricata may have CA isomers with their respective molecular weights at around 60 and 55 k Da, at least one of which is Cd-bound. In addition, trace amounts of Cd in purified CA significantly increased with the supplied Cd concentration in nutrient solution(5–25 μmol L~(-1)). The results suggested that Cd may play a biological role by enhancing the activities and forming the active Cd-specific CA in the hyperaccumulator P. divaricata.  相似文献   

7.
Cadmium(Cd) is highly toxic to plants, animals, and humans. Limited information is available on the role of nitric oxide(NO)and/or 24-epibrassinolide(EBR) in response of plants to Cd stress. In this study, a hydroponic experiment was performed to investigate the effects of NO and/or EBR on peanut plants subjected to Cd stress(200 μmol L~(-1)) with sodium nitroprusside(SNP, an exogenous NO donor)(250 μmol L~(-1)) and/or EBR(0.1 μmol L~(-1)) addition. The results showed that Cd exposure inhibited plant growth, and this stress was alleviated by exogenous NO or EBR, and especially the combination of the two. Treatment with Cd inhibited the growth of peanut seedlings, decreased chlorophyll content, and significantly increased the Cd concentration in plants. Furthermore, the concentration of reactive oxygen species(ROS) markedly increased in peanut seedlings under Cd stress, resulting in the accumulation of malondialdehyde(MDA) and proline in leaves and roots. Under Cd stress, applications of SNP, EBR, and especially the two in combination significantly reduced the translocation of Cd from roots to leaves, increased the chlorophyll content, decreased the concentrations of ROS, MDA, and proline, and significantly enhanced the activities of superoxide dismutase(SOD), peroxidase(POD), and catalase(CAT) in peanut seedlings. Exogenous NO and/or EBR also stimulated the activities of nitrate reductase(NR)and nitric oxide synthase(NOS) and increased the contents of antioxidants, such as ascorbic acid(AsA) and reduced glutathione(GSH). Furthermore, exogenous NO and/or EBR enhanced Cd accumulation in the cell wall and thus decreased Cd distribution in the organelles in the roots. The concentrations of calcium(Ca), iron(Fe), magnesium(Mg), and zinc(Zn) were also regulated by exogenous NO or EBR, and especially by the two in combination. These results indicated that SNP and EBR, alone and particularly in combination, can mitigate the negative effects of Cd stress in peanut plants.  相似文献   

8.
盐胁迫下马蔺的生理反应研究   总被引：2，自引：0，他引：2  
Chinese iris （Iris lactea Pall. var. chinensis （Fisch） Koidz.）, a robust iridaceous plant, is widespread in arid and semiarid regions with high salinity. However, the mechanism of its salt tolerance is not well understood. In this study, plant growth, water status, content and distribution of inorganic ions, cell membrane permeability, and proline content of I. laetea under salt stress were investigated using nutrient solutions with six NaCl concentrations ranging from 0 to 350 mmol L^-1. The results indicated that the biomass, height, fresh weight, K^＋ content, and K^＋/Na^＋ and Ca^2＋/Na^＋ ratios decreased with increasing NaCl stress, whereas plant water deficit and contents of Na^＋ and Cl- increased with increasing NaCl stress. In all salt treatments, water deficit of shoots was found to be higher than that of roots and had a positive correlation with salt concentration. When the NaCl concentration was less than 280 mmol L^-1, the ion absorption selectivity ratio and the transportation selectivity ratio sharply increased with increasing NaCl stress. Under medium salt stress, I. lactea exhibited a strong K^＋ selective absorption and the transportation of K^＋ from roots to shoots increased, whereas Na^＋ was not transported and was mostly retained in roots. The plants were able to maintain osmotic adjustment through the accumulation of Na^＋, Cl-, and proline. On the basis of its biomass production under salt stress, I. lactea could be considered as a facultative halophyte.  相似文献   

9.
A experiment was carried to evaluate the effects of Al on growth, accumulations of free proline and amino acid in 2 wheat cultivars (Triticum aestivum L.), Yangmai No.5 and Jian 864, differing in Al sensitivity. Plants grew initially in a nutrient solution without Al for 13 days before the addition of Al and finally in a nutrient solution containing 0.5mmol Al (L-1) for 19 days. The results showed that there were marked decreases in dry weight, relative growth rate (RGR) and net assimilation rate (NAR) of Al-treated seedlings compared with control plants. The Al effects were more evident in Yangmai No.5 than Jian 864. Leaf area ratio(LAR) was little affected by Al. RGR was highly correlated with NAR rather than LAR. Aluminum increased the concentrations of free proline and total free amino acid in shoots of both the cultivars. The increases were greater in Yangmai No.5 than in Jian 864. The percentage of free proline in total amino acid in shoots was not affected by Al treatment. It was possible that accumulation of proline was merely a symptom of Al injury. The concentrations of total nitrogen in Al-treated plants did not significantly differ from those of control plants. Nitrate reductase activity (NRA) in leaves was severely decreased by Al, and a greater decrease was noted in Yangmai No.5 than in Jian 864, but NRA in roots of both the cultivars was not affected. The decreases in NRA might be an indirect (accumulation of amino acid) rather than a direct result of Al toxicity.  相似文献   

10.
Environmental pollution with chromium(Cr) is harmful to humans, animals and plants, while in plants it causes diminished growth,anatomical alterations and death. In the present study, the potential value of marigold(Tagetes erecta) in the phytoremediation of Cr has been investigated. The randomized experimental design involved the exposure of plants to nutrient solutions containing 0.00,0.04, 0.08, 0.12, 0.16 or 0.24 mmol L~(-1)Cr(Ⅲ). Chromium toxicity was observed at Cr(Ⅲ) concentrations ≥ 0.12 mmol L~(-1) as demonstrated by diminished growth of the aerial parts and reduced density of the root system. Increasing Cr(Ⅲ) concentrations in the nutrient solution resulted in a higher bioaccumulation of total Cr in the tissues, although translocation from roots to aerial parts was not efficient(maximum value of 25% at 0.12 mmol L~(-1)Cr(Ⅲ)). The Cr bioaccumulation was up to 11-fold greater in roots than in the aerial parts. Tagetes erecta exhibited leaf plasticity when exposed to Cr, indicating the existence of a tolerance mechanism to Cr in this species. Chromium caused a reduction in xilem vases, resulting in a plastic effect in T. erecta leaves that increased the metal tolerance in culture solution. Tagetes spp. are potential Cr hyperaccumulators; at Cr(Ⅲ) concentrations up to 0.12 mmol L~(-1), the plants accumulated levels above that proposed for hyperaccumulators and still maintained a considerable growth and even flourished. However, this study was conducted in nutrient solution, and studies on species confirmation as Cr hyperaccumulator should be conducted in soils for further clarification.  相似文献   

11.
Abstract

Seventeen soybean cultivars were screened to discern differences in aluminum (Al) sensitivity. The Sowon (Al-tolerant) and Poongsan (Al-sensitive) cultivars were selected for further study by simple growth measurement. Aluminum-induced root growth inhibition was significantly higher in the Poongsan cultivar than in the Sowon cultivar, although the differences depended on the Al concentration (0, 25, 50, 75 or 100?μmol?L–1) and the amount of exposure (0, 3, 6, 12 or 24?h). Damage occurred preferentially in the root apex. High-sensitivity growth measurements using India ink implicated the central elongation zone located 2–3?mm from the root apex. The Al content was lower 0–5?mm from the root apices in the Sowon cultivar than in the apices of the Poongsan cultivar when exposed to 50?μmol?L–1 Al for 12?h. Furthermore, the citric acid exudation rate was more than twofold higher in the Sowon cultivar. Protein production of plasma membrane (PM) H+-ATPase from the root apices (0–5?mm) was upregulated in the presence of Al for 24?h in both cultivars. This activity, however, decreased in both cultivars treated with Al and the Poongsan cultivar was more severely affected. We propose that Al-induced growth inhibition is correlated with changes in PM H+-ATPase activity, which is linked to the exudation of citric acid in the root apex.  相似文献   

12.
为探讨铝(Al)胁迫条件下脱落酸(ABA)调控植物根系有机酸分泌的机制,进行了ABA与Al诱导大豆根系柠檬酸分泌的关系试验。结果表明:1)外源ABA和ABA合成抑制剂fluridone分别提高和降低了Al诱导的大豆根尖ABA含量的增加,但对根系柠檬酸分泌量均无影响,ABA对根系内源柠檬酸含量和柠檬酸合成酶的活性也没有影响;2)分根试验表明,与Al直接接触的根部(Part A)内源ABA含量发生变化,且有柠檬酸的分泌,而不与Al直接接触的根部(Part B)内源ABA含量也发生变化,但没有柠檬酸分泌;3)Al胁迫下,大豆耐Al基因型柠檬酸分泌量远高于敏感基因型,但二者的内源ABA含量却没有差异;4)30μmol AlCl3处理,在0~12 h柠檬酸分泌速率和内源ABA含量随Al处理时间增加而增加,去除Al胁迫时(12~18 h),柠檬酸分泌速率继续增加,但内源ABA含量则迅速下降。综合以上结果,推测ABA不是通过提高Al诱导柠檬酸分泌来调控大豆耐Al性。  相似文献   

13.
《Journal of plant nutrition》2013,36(11):2047-2066
Abstract

Eighteen soybean genotypes differing in aluminum (Al) tolerance were used to investigate genotypic differences in Al-induced citrate exudation and its role in Al tolerance. Aluminum accumulation and localization in soybean roots were examined by analysis of total Al and hematoxylin staining. Soybean genotypes exhibited a wide range of Al tolerance. Based on relative root elongation, several Al-tolerant genotypes from Brazil such as B1, B10, and B15 were more tolerant than the Al-tolerant PI 416937 (PI) and Perry. All soybeans exuded citrate in response to Al stress, and some Al-sensitive genotypes secreted more citrate than tolerant ones, showing no correlation between the Al tolerance and Al-induced citrate exudation. Further study found that both copper (Cu) and cadmium (Cd) stimulated citrate and malate exudation in soybean, indicating that organic acid secretion is not specifically induced by Al. Aluminum concentrations were significantly higher in 2–3 and 3–4 cm of segments than that in 0–1 and 1–2 cm segments under 15 μM AlCl3. Both the root mature zone and apex were heavily stained by hematoxylin after exposure to 10, 15, or 20 μM AlCl3 (24 h), whereas root elongation zone was not stained. After exposure to 50 μM AlCl3 for 20 min, the Al-tolerant PI was less stained by hematoxylin than the Al-sensitive Young, suggesting that Al accumulation in root apices seem to be an immediate response to Al stress, and related to differential Al sensitivity. Present results suggest that citrate secretion induced by Al stress may not be a key mechanism responsible for the differential Al tolerance of some soybean genotypes and other mechanism(s) conferring Al exclusion should exist and operate immediately after exposure to Al stress.  相似文献   

14.
《Journal of plant nutrition》2013,36(7):1281-1293
Abstract

In order to investigate the combined effect of drought stress and aluminum (Al) toxicity on citrate exudation in soybean, hydroponic cultivation with addition of Al and PEG-6000 was conducted to simulate Al-toxic dry soil. Results showed that 2-day exposure of soybeans to 5.5% (w/v) PEG-6000 or 100 µM AlCl3 mainly hindered root growth, while combined exposure to PEG and Al (PEG/Al) reduced both root and shoot growth. Photosynthetic rate of first trifoliolate for the Al-tolerant genotype PI 416937 (PI) was not affected by imposition of 5.5% PEG/100 µM AlCl3 (38–40 h), whereas photosynthetic rate for the Al-sensitive genotype YC was significantly reduced. Based on root fresh weight, Al-induced citrate exudation in the roots of soybean genotypes recovered from pre-treatment with 5.5 or 9% PEG was not altered, but was increased in the plants pretreated with 7% PEG without recovery. After 2 days of recovery from 2-day combined exposure to 5.5% PEG/100 µM AlCl3, the Al-tolerant PI exuded more citrate than its control, but the Al-sensitive YC exuded significantly less citrate than its corresponding control. Split root experiment revealed that Al-induced citrate exudation in one half of the root system was significantly reduced by exposing the other half of the root system to 0.5 mM CaCl2 solution containing 9% PEG or 9% PEG/50 µM AlCl3. However, organic acid secretion was not observed in the half of the root system in the Ca solution when the other part of the root system was exposed to the Ca solution containing 50 µM AlCl3, 9% PEG or 9% PEG/50 µM AlCl3. This suggests that no Al- or drought-induced signals such as ABA are involved in the citrate secretion in soybean.  相似文献   

15.
Phytotoxicity of aluminum (Al) has become a serious problem in inhibiting plant growth on acid soils. Under Al stress, the changes of rhizosphere pH, root elongation, absorption of Al by wheat roots, organic acids exuded from roots, and some main factors related to Al-tolerant mechanisms have been studied using hydroponics, fluorescence spectrophotometry, and high performance liquid chromatography (HPLC). Two wheat cultivars, Brevor and Atlas66, differing in Al tolerance are chosen in the study. Accordingly, the rhizosphere pH has a positive effect on Al tolerance. Atlas66 (Al-tolerant) has higher capability to maintain high rhizosphere pH than Brevor (Al-sensitive) does. High pH can reduce Al3+ activity and toxicity, and increase the efficiency of exuding organic acids from the roots. More inhibition of root elongation has been found in Brevor because of the exposure of roots to Al3+ solution at low pH. Brevor accumulate more Al in roots than Atlas66 even at higher pH. Al-induced exudation of malic and citric acids has been found in Atlas66 roots, while no Al-induced organic acids have been found in Brevor. These results indicate that the Al-induced secretion of organic acids from Atlas66 roots has a positive correlation with Al tolerance. Comprehensive treatment of Al3+ and H+ indicates that wheat is adversely influenced by excess Al3+, rather than low pH.  相似文献   

16.
小麦的铝毒及耐性   总被引：11，自引：2，他引：11  
为探明Al的毒性和忍耐机理 ,比较了Scout 66和Atlas 66Al敏感和抗性的 2个小麦品种的根对Al的积累模式、根细胞壁对Al的吸附以及Al诱导的有机酸的分泌。结果表明 ,Al对Scout 6 6根伸长的抑制作用较Atlas 66明显。根系吸收的Al主要积累于 0至 5mm根尖处。Scout 6 6的根尖及Al处理后分离的根尖细胞壁对Al的积累量大于Atlas 6 6。但是 ,Al处理前分离根尖细胞壁 ,Al处理后细胞壁对Al的吸附量两品种间无显著差异。Al可诱导Atlas 6 6的根系分泌苹果酸 ,而Scout 6 6的分泌物中未发现Al诱导的有机酸。这些结果表明 ,Atlas 6 6的根尖及其细胞壁较Scout 66积累较少的Al,这种差异与Al诱导的有机酸分泌有关 ,而与根尖细胞壁固有的吸附Al的能力无关  相似文献   

17.
施用磷、钙对红壤上胡枝子生长和矿质元素含量的影响   总被引：3，自引：3，他引：3  
孙清斌  董晓英  沈仁芳 《土壤》2009,41(2):206-211
采用红壤土培试验,研究了施用P、Ca对耐Al性不同的两个胡枝子品种的生长和矿质元素含量的影响.结果表明,单独 +P处理显著增加了耐Al 品种根和地上部生物量,而对Al敏感品种无影响;单独 +Ca处理显著促进了Al敏感品种根部的生长,而对耐Al品种的生长无影响;+P+Ca处理显著增加了两个品种根和地上部生物量.耐性品种地上部Al含量显著低于敏感品种,而根部Al含量无显著差异.两个品种体内P含量在 +P处理时耐性品种显著高于敏感品种,其他处理品种间无显著差异.整体上,胡枝子体内Ca、K、Mn和Mg含量耐性品种大于敏感品种,Fe含量反之.结果表明,低P胁迫是酸性土壤上耐Al胡枝子品种生长的主要限制因子,增施P肥效果明显,而对于Al敏感品种,Al毒是其生长的首要限制因子,只有施用石灰后对其加P,生物量才能提高.耐性品种根部有阻碍Al 向地上部运输的机制,而这种机制与体内P含量较高有着直接或间接的关系.另外,推测耐Al胡枝子品种对其他养分的吸收利用能力也较强.  相似文献   

18.
以苗期表现为耐铝性具有明显差异的 10份大麦基因型为材料 (耐铝和铝敏感基因型各 5个 ) ,研究铝胁迫条件下生育后期植株生物量、铝和养分元素含量的差异。结果表明 ,铝胁迫抑制植株干物质积累 ,但抑制程度因基因型而异 ,上 70 119等铝敏感基因型受影响较大 ,且两类基因型之间的差异成熟期明显大于乳熟期。铝胁迫显著降低敏感基因型的子粒产量 ,但对耐性基因型的影响较小。铝胁迫增加所有基因型根系和地上部的Al含量 ,但增加幅度基因型之间存在着明显差异 ,耐铝基因型增加较少 ,而铝敏感基因型表现显著增加。酸性土壤上 ,根系和地上部N、P、K、Ca、Mg和Zn等养分含量 ,铝敏感基因型显著减少 ,耐铝基因型受影响较小。  相似文献   

19.
Cu, Zn, and Cd acquisition by two spinach cultivars depending on P nutrition and root exudation Within a spectrum of 11 spinach cultivars (cvs) differences in the Cu, Zn, and Cd contents of shoots had been noticed. The aim of this study was therefore to analyze in more detail the acquisition of Cu, Zn, and Cd by the most differing cultivars (Tabu and Monnopa) in dependence on P nutrition. The plants were grown in a low phosphorus Luvisol (pH 6.3; total contents Cu: 89, Zn: 297, Cd: 2.4 mg kg—1) with two phosphorus levels in pots under natural conditions. For the determination of inflow, root length/shoot weight ratio and of the Cu, Zn, and Cd concentration in the soil solution (rhizosphere) plants were harvested 26 and 40 days after sowing. Root exudation of organic acids of the two cvs was measured 35 days after growing in quartz sand with different P supply. Both cultivars responded to P fertilizer by doubling their shoot weight. With increased P supply (0.68—0.77% P in shoot‐DM) both cultivars showed similar heavy metal contents in the shoot resulting from similar root length/shoot weight ratios (RSR) and net uptake rates of the three elements as well as the same element concentrations in the rhizosphere soil solution. Under P deficiency, however, cv. Tabu (0.52% P in shoot‐DM) showed in comparison with cv. Monnopa (0.48% P) higher Cu, Zn, and Cd contents of shoots although its RSR was smaller than that of cv. Monnopa. However, the inflow for Cu was higher and for Zn and Cd significantly higher compared with cv. Monnopa. This result of cv. Tabu corresponded with higher concentrations of Cu, Zn, and Cd of its rhizosphere soil solution, and its higher exudation rates of oxalate, citrate, and malate (3.9; 1.0; 0.7 nmol cm—1 h—1). The corresponding values for cv. Monnopa were: 1.7; 0.3; 0.4 nmol cm—1 h—1. The mobilization of Cu, Zn, and Cd by the excreted organic acids seems to be responsible for the higher Cu, Zn, and Cd inflow of cv. Tabu.  相似文献   

20.
铝诱导大豆根系有机酸分泌是其解铝毒的一种重要机制,该过程需要消耗能量,然而有关能量消耗的定量研究还未见报道。本文比较了铝胁迫条件下,两个大豆品种根尖有机酸分泌、 腺苷酸、 无机磷、 细胞质pH值等指标的变化。结果表明,铝处理（25 mol/L）明显诱导大豆根系苹果酸和柠檬酸的分泌。与对照相比,铝胁迫条件下中豆32和本地2号的根尖ATP含量分别降低40.1%和13.2%,根系细胞质子跨膜电化学势差分别增加1711.8和570.6 J/mol,然而,根尖无机磷浓度变化差异不大。运用Nernst-Gibbs方程定量计算自由能变化,发现中豆32和本地2号根尖细胞自由能分别消耗16.13 kJ/mol和14.59 kJ/mol, 中豆32分泌单位苹果酸和柠檬酸的能量消耗分别为0.96 kJ/mol和3.15 kJ/mol,本地2号则为2.01 kJ/mol和5.68 kJ/mol。这表明不同耐铝性大豆品种分泌有机酸消耗的能量存在差异,该结果为筛选耐铝作物品种提供了新思路。  相似文献   

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