草类对重金属胁迫的生理生化响应机制

随着我国工业化进程不断加快,作为工业化基本生产资料的重金属不断被释放到生物圈中,并通过食物链传递给动物或人,给人类健康带来严重危害。草类分布广泛,有一定的抵抗能力,一些草类甚至还具有重金属超富集能力,在生物修复中发挥重要作用。本文就重金属胁迫对草类种子萌发、根系活力和生物量方面的影响以及草类的抗性机制(脯氨酸、抗氧化酶系统、谷胱甘肽、隔离、菌根和水杨酸)等研究现状进行论述,并阐明草类对重金属镉、锌、铜、铬、铅和汞的富集效应及其耐性机制,以期为今后草类耐重金属胁迫品种的选育和耐重金属胁迫分子机制的研究,提供现实依据和理论基础。     

Effects of Zinc on Root Morphology and Antioxidant Adaptations of Cadmium-Treated Sedum alfredii H.

ABSTRACT

The study demonstrated S. alfredii is an excellent cadmium (Cd)/zinc (Zn) hyperaccumulator as Cd and Zn concentrations in leaves reached 2,183 and 13,799 mg kg^?1 DW, respectively. There was a significant increase in root morphological parameters induced by 50 and 500 μM Zn supplement; however, a sharp decrease in these parameters occurred when treated with 100 μM Cd +1000 μM Zn. The inhibited root dehydrogenase activity in 100 μM Cd treated plants was restored to control levels when supplemented with 500 μM Zn. Moderate Zn supplement did not produce significant changes in (malondialdehyde) MDA concentrations as compared with those treated with Cd alone. Variations of the antioxidative enzymes proved an ineffective role in coping with metal-stress in S. alfredii. Combined Cd and Zn treatment significantly enhanced ascorbic acid (AsA) and glutathione (GSH) contents in leaves of S. alfredii, as compared with those treated with Cd alone. Thus, Zn may rely on the involvement of GSH in detoxification and tolerance.     

试论超附吸室内空气污染物观赏植物的绿化模式

对超附吸室内空气污染物观赏植物的种类进行了归纳总结。主要探讨了当前超附吸室内空气污染物观赏植物的室内绿化模式和造景方法,并结合室内不同位置空间的应用进行了实例分析。     

Root morphology of Thlaspi goesingense Hálácsy grown on a serpentine soil

The contribution of root morphology to enhanced uptake of heavy metals by hyperaccumulating plants is not well understood. The objective of this study was to describe root‐morphological characteristics of the natural nickel (Ni) hyperaccumulator Thlaspi goesingense Hálácsy. Plant samples were collected from a serpentine site near Redlschlag (East Austria), characterized by large soil Ni concentrations. Roots were evaluated for mass, length, surface area, diameter, and related ratios using an image‐analysis approach. Results showed that on the indigenous site, T. goesingense Hálácsy developed a fine‐branched root system, confined within a shallow soil depth. Coarse roots (>1 mm) accounted for about 60% of the total root mass (fresh and dry), while their contribution to the surface area and especially to the length of the system was small. Conversely, fine roots (<1 mm) represented 99% of the total root length and 88% of the surface area. The largest proportion of root length and area was found in the smallest diameter class of 0.0 to 0.5 mm. Shoot‐biomass production per unit root was high, in spite of the adverse soil conditions. Roots accounted for 8% of the total plant mass and about 4% of the total Ni accumulation. We conclude that the root system of natively grown T. goesingense Hálácsy exhibits a potential for enhanced Ni extraction from soil, since it mainly consists of very fine roots with extended absorptive area.     

Chemical changes in the rhizosphere of metal hyperaccumulator and excluder Thlaspi species

Rhizosphere processes involved in hyperaccumulation and exclusion of metals are still largely unknown. Therefore, we conducted a rhizobag experiment on contaminated and non‐contaminated soils to investigate the chemical changes in the rhizosphere of the hyperaccumulators Thlaspi goesingense and T. caerulescens, and the metal‐excluder T. arvense. Root growth was restricted to the rhizobags separated by a nylon membrane (7 μm \x 25 μm mesh size) from surrounding bulk soil. Depletion of labile Zn in rhizosphere could not explain the amount of metals accumulated in T. caerulescens, whereas the difference in EDTA‐extractable Zn even exceeded total plant uptake. Substantially increased DOC in T. arvense rhizosphere indicates alleviation of phytotoxicity by formation of metal‐organic complexes. Hyperaccumulation and depletion of labile Zn in the rhizosphere was observed for T. goesingense grown on contaminated soil. On non‐contaminated soil, Zn was accumulated but labile Zn in rhizosphere was not changed. Nickel present in background concentrations in both soils was accumulated by T. goesingense only when grown on non‐contaminated soil. In contrast, labile Ni in the rhizosphere was increased in both soils, suggesting a general tendency of Ni mobilization by T. goesingense.     

Comparison of Root‐System Efficiency and Arsenic Uptake of Two Fern Species

Abstract

This greenhouse study examined the root characteristics (biomass, length, area, and diameter) and root uptake efficiency of Pteris vittata, an arsenic (As) hyperaccumulator and Nephrolepis exaltata, not an As hyperaccumulator, in relation to plant uptake of As and nutrients in an As‐contaminated and a control soil. After 8 weeks of growth, on a per plant basis, P. vittata accumulated 7.3–8.8 g of biomass and removed 2.51 mg of As from the As‐contaminated soil compared to 2.4–2.7 g of biomass and 0.09 mg of As for N. exaltata. This was partially because P. vittata developed a more extensive root system, 2.4–3.8 times greater (biomass, length, and area), and possessed a greater proportion of fine roots than N. exaltata. In addition, the As root‐uptake efficiency (defined as As concentrations in plant tissue per unit root) for fronds of P. vittata was 15–23 times greater than that of N. exaltata in both soils. Whereas N. exaltata removed phosphorus (P) more efficiently from the soils, P. vittata removed As more efficiently. The larger root biomass coupled with more efficient root‐uptake systems for As may have contributed to As hyperaccumulation by P. vittata.     

不同氮形态对东南景天镉积累的影响

    通过水培试验,研究不同氮形态对2种生态型东南景天生长和镉吸收积累的影响.结果表明,外加(NH4)2SO4、Ca(NO3)2或NH4NO3均能显著提高超积累生态型东南景天地上部生物量及叶绿素含量.且无论在低镉(10 μmol·L-1)还是高镉(100 μmol·L-1)条件下,以(NH4)2Sv处理的增幅最大.不同氮形态对2种生态型东南景天地上部镉含量没有显著影响,而在一定程度上提高了根系镉的含量.3种氮形态显著提高了2种生态型东南景天地上部和根系的镉积累量,对超积累生态型东南景天,无论在何种镉水平下,(NH4)2SO4处理效果明显好于Ca(NO3)2或NH4NO3处理.本研究结果表明不同氮形态对东南景天Cd积累的促进顺序为:NH4+-NNO3--N,因此从植物修复角度考虑,在Cd污染土壤中施用适量的(NH4)2SO4提高超积累植物东南景天的生物量和地上部镉积累量具有重要的应用价值.     

Screening of Amaranth Cultivars （Amaranthus mangostanus L.） for Cadmium Hyperaccumulation

The potential harm of soil cadmium pollution to ecological environment and human health has been increasingly widely concerned. Phytoremediation, as a kind of new and effective technology, has become an important method for cleaning up cadmium in contaminated sites. The amaranth （Amaranthus mangostanus L.） is widely distributed and has abundant varieties in China, its rapid growth and large biomass can be served as candidate for cadmium hyperaccumulators for phytoremediation. To obtain cadmium hyper-accumulator, Cd uptake in 23 amaranth cultivars from different ecological region was investigated under hydroponic culture condition. Meanwhile, pot experiment was established to probe phytoremediation potentiality of Cd contaminated soil by amaranth. Three treatment （Cd 5, 10, and 25 mg kg^-1） were imposed to red soil, yellow brown soil, and vegetable soil. The results showed that under hydroponic culture with Cd 3 mg L^-1, the cadmium concentration in the shoots of the cultivar Tianxingmi reached 260 mg kg^-1, and its total cadmium uptake was the highest among various cultivars. In the treatment Cd 25 mg kg^-1, the cadmium concentration in the shoots of the cultivar Tianxingmi reached 212 mg kg^-1, while bioaccumulation factor and shoot purification rate reached 8.50 and 3.8%, respectively. Further, the total biomass and shoot biomass were not decreased significantly under Cd exposure. These results suggested that cultivar Tianxingmi is a typical Cd hyperaccumulator, and can be expected to be used in phytoremediation of Cd contaminated soil.     

有机和无机氮对东南景天生长和镉积累的影响比较

通过水培试验,研究了有机和无机形态氮对两种生态型东南景天生长和镉积累的影响.结果表明,无论在低镉(10μmol·L-1)还是高镉(100 μmol·-1)条件下,与对照(T1)相比,外加无机形态氮(尿素)均能显著提高两种生态型东南景天地上部的生物量和叶绿素含量(P＜0.05);在低镉条件下,外加无机形态氮只能显著提高超积累生态型东南景天地上部镉积累量和非超积累生态型东南景天根部镉积累量(P＜0.05),在高镉条件下,外加无机形态氮对两种生态型东南景天体内镉积累量没有显著影响(P＞0.05).而无论在低镉还是高镉条件下,与对照(T1)相比,外加有机形态氮(精氨酸)能显著降低超积累生态型东南景天根系的生物量和叶绿素含量(P＜0.05);在低镉条件下,外加有机形态氮能显著提高两种生态型东南景天体内镉含量(P＜0.05),在高镉条件下,外加有机形态氮对两种生态型东南景天体内镉含量没有显著影响(P＞0.05).     

Phytoextraction of Cd and Zn with Thlaspi caerulescens in field trials

Abstract. Phytoextraction is the remediation of heavy metal contaminated soils using plants that take up metals. Hyperaccumulating plants such as Thlaspi caerulescens are often studied for their possible use for decontamination of Cd and Zn rich soils, but few field trials have been reported, although they are necessary to validate the results of hydroponic and pot studies. This article reports field data for T . caerulescens grown on a calcareous and an acidic soil, both contaminated 20 years ago by either atmospheric depositions or septic-tank wastes. Accelerated cropping using transplants grown three times in eight months was compared to Thlaspi sown twice during the same period. Both were followed by one crop of sown Thlaspi . High Cd and Zn concentrations in the plant shoots compensated for the low biomass production. Annual metal exports with transplanted Thlaspi were 130 g Cd ha⁻¹ and 3.7 kg Zn ha⁻¹ on the calcareous soil and 540 g Cd ha⁻¹ and 20 kg Zn ha⁻¹ on the acidic soil. We concluded that within the framework of the Swiss legislation, remediation of Cd-contaminated soils could be achieved within less than 10 years with one crop of Thlaspi per year, but differences in soil properties could affect the rate of phytoextraction significantly. Total Zn content in both soils was too high to be remediated by T . caerulescens in a realistic time span. Thlaspi did not decrease the NaNO₃-extractable fraction of Cd or Zn in either of the soils.