丛枝菌根对喜树幼苗生长和氮、磷吸收的影响

喜树(Camptotheca acuminata)是我国特有的多年生亚热带落叶阔叶树种,因其次生代谢产物喜树碱具有良好的抗肿瘤活性而受到人们的广泛关注。该文通过温室盆栽接种试验,观察了2属6种丛枝菌根真菌即蜜色无梗囊霉(Acaulospora mellea)、光壁无梗囊霉(A. laevis)、木薯球囊霉(Glomus manihot)、地表球囊霉(G. versiforme)、幼套球囊霉(G. etunicatum)和透光球囊霉(G. diaphanum)对喜树幼苗生长和氮、磷养分吸收的影响。结果表明,丛枝菌根的形成对喜树幼苗的生长以及氮、磷营养的吸收均有影响。从生物量看,除幼套球囊霉和光壁无梗囊霉侵染形成的丛枝菌根喜树幼苗与无菌根幼苗(CK)差异不显著外,其余菌根幼苗的生物量均明显大于无菌根幼苗,透光球囊霉和蜜色无梗囊霉菌根幼苗尤为突出,分别达到无菌根幼苗的1.9和1.4倍。丛枝菌根的形成似乎不利于喜树幼苗的氮素营养吸收,并且主要体现在叶片的氮含量上。相反,丛枝菌根形成总体上促进喜树幼苗对磷素营养的吸收,并且主要体现在根的磷含量上。与无菌根幼苗比,所有菌根幼苗根的氮、磷分配比例增加,而叶片的氮、磷分配比例减少。     

接种后共培养时间对丛枝菌根喜树幼苗喜树碱含量的影响

在前期工作中利用蜜色无梗囊霉(Acaulospora mellea)和根内球囊霉(Glomus intraradices)从接种时期角度分析了喜树碱含量与菌根形成过程对应关系的基础上,通过温室盆栽接种试验,继续观察了这两种丛枝菌根真菌接种后与喜树(Camptothecaacuminata)幼苗的共培养时间对喜树幼苗喜树碱积累的影响。分别用两种菌根真菌每隔7d接种一批喜树幼苗,第5批接种7 d后采样,获得菌根真菌与喜树幼苗共培养时间分别为35、28、21、14、7 d的喜树幼苗样品,测定了菌根浸染状况和喜树碱含量。结果表明:(1)接种两种丛枝菌根真菌均促进了喜树幼苗喜树碱的积累,表现为喜树碱含量和产量(单株幼苗所含的喜树碱量,喜树碱含量与幼苗生物量的乘积)的显著提高。(2)从接种后共培养时间的效果看,两种菌根幼苗各器官(根、茎、叶)及全株喜树碱含量和产量均呈现随着丛枝菌根真菌与喜树幼苗共培养时间的增加而增加的趋势。两种菌根幼苗的根和茎、根内球囊霉菌根幼苗的叶片和全株的的喜树碱含量和产量,在共培养时间增加至21 d时趋于稳定,而蜜色无梗囊霉菌根幼苗的叶片和全株的喜树碱含量和产量在共培养时间增加至28 d时达到最高,其后略有降低。(3)两种丛枝菌根真菌的侵染率和侵染强度同样随共培养时间的增加而增加,至共培养28 d后无显著变化。在一定共培养时间范围内,喜树碱含量和产量的变化与丛枝菌根真菌的侵染及菌根形成之间具有对应性。     

接种时期对丛枝菌根喜树幼苗喜树碱含量的影响

喜树(Camptotheca acuminata)是我国特有的多年生亚热带落叶阔叶树种, 因其次生代谢产物喜树碱具有良好的抗肿瘤活性而受到人们的广泛关注。通过温室盆栽接种试验, 观察了喜树幼苗不同生长时期接种蜜色无梗囊霉(Acaulospora mellea)和根内球囊霉(Glomus intraradices)对喜树幼苗喜树碱积累的影响。结果表明接种两种丛枝菌根真菌均促进了喜树幼苗喜树碱的积累, 表现为喜树碱产量(单株幼苗所含的喜树碱量, 喜树碱含量与幼苗生物量的乘积)的显著提高。进一步分析发现, 接种丛枝菌根真菌导致幼喜树苗喜树碱产量的提高, 早期(幼苗出土20天)接种主要是源于喜树碱含量的提高, 特别是叶片喜树碱含量的提高, 而晚期(幼苗出土60天)接种则主要是源于幼苗生物量的增加。     

接种AM真菌对喜树幼苗生长及光合特性的影响

 喜树(Camptotheca acuminata)是我国特有的多年生亚热带落叶阔叶树种, 因其次生代谢产物喜树碱具有良好的抗肿瘤活性而备受关注。通过温室盆栽接种试验, 观察了3属6种丛枝菌根(AM)真菌木薯球囊霉(Glomus manihot)、地表球囊霉(G. versiforme)、透光球囊霉(G. diaphanum)、蜜色无梗囊霉(Acaulospora mellea)、光壁无梗囊霉(A. laevis)和弯丝硬囊霉(Sclerocystis sinuosa)对喜树幼苗生长及光合特性的影响。结果表明, 除地表球囊霉外, 其余菌根幼苗生物量显著高于无菌根幼苗, 蜜色无梗囊霉、弯丝硬囊霉和透光球囊霉的菌根幼苗生物量分别达到无菌根幼苗的1.6倍、1.4倍和1.3倍。与无菌根幼苗相比, 蜜色无梗囊霉菌根幼苗叶片的净光合速率(P_n)、气孔导度(G_s)和蒸腾速率(T_r)均有显著提高, 而胞间CO₂浓度(C_i)与气孔限制值(L_s)则变化不明显。接种透光球囊霉、蜜色无梗囊霉、光壁无梗囊霉和弯丝硬囊霉的喜树幼苗叶片叶绿素a含量、总叶绿素含量、叶绿素a/b和类胡萝卜素含量均显著高于无菌根幼苗, 而叶绿素b含量只有木薯球囊霉和弯丝硬囊霉菌根幼苗显著高于无菌根幼苗。接种AM真菌对喜树幼苗叶片叶绿素荧光参数影响较小, 只有透光球囊霉菌根幼苗叶片的最大光能转换效率(F_v/F_m)显著高于无菌根幼苗, 接种木薯球囊霉和弯丝硬囊霉的喜树幼苗的PSⅡ有效光化学量子产量(EQY)显著高于无菌根幼苗, 弯丝硬囊霉菌根幼苗的光化学淬灭(qP)显著高于无菌根幼苗, 非光化学淬灭(NPQ)则显著低于无菌根幼苗。     

金沙江干热河谷(元谋段)丛枝菌根真菌多样性研究*

从金沙江干热河谷(元谋段)75种植物的根际土壤中分离鉴定了44种丛枝菌根真菌, 分属无梗囊霉属Acaulospora、古孢霉属Archaeospora、内养囊霉属Entrophospora、巨孢囊霉属Gigaspora、球囊霉属Glomus和盾巨孢囊霉属Scutellospora, 其中,球囊霉属和无梗囊霉属为金沙江干热河谷中丛枝菌根真菌的优势属。齿状无梗囊霉A. denticulata、刺状无梗囊霉A. spinosa、瘤状无梗囊A. tuberculata,近明球囊霉Glomus claroideum、明球囊霉G. clarum、根内球囊霉G. intraradices、单孢球囊霉G. monosporum、弯丝球囊霉G. sinuosa是金沙江干热河谷(元谋段)的优势种。金沙江干热河谷土壤中丛枝菌根真菌的孢子密度为5~6400个/100g土壤,平均1504;每个根际土壤中丛枝菌根真菌的物种丰富度1~18种,平均9种。     

金沙江干热河谷(元谋段)丛枝菌根真菌多样性研究

从金沙江干热河谷(元谋段)75种植物的根际土壤中分离鉴定了44种丛枝菌根真菌, 分属无梗囊霉属Acaulospora、古孢霉属Archaeospora、内养囊霉属Entrophospora、巨孢囊霉属Gigaspora、球囊霉属Glomus和盾巨孢囊霉属Scutellospora, 其中,球囊霉属和无梗囊霉属为金沙江干热河谷中丛枝菌根真菌的优势属。齿状无梗囊霉A. denticulata、刺状无梗囊霉A. spinosa、瘤状无梗囊A. tuberculata,近明球囊霉Glomus claroideum、明球囊霉G. clarum、根内球囊霉G. intraradices、单孢球囊霉G. monosporum、弯丝球囊霉G. sinuosa是金沙江干热河谷(元谋段)的优势种。金沙江干热河谷土壤中丛枝菌根真菌的孢子密度为5~6400个/100g土壤,平均1504;每个根际土壤中丛枝菌根真菌的物种丰富度1~18种,平均9种。     

金沙江干热河谷（元谋段）丛枝菌根真菌多样性研究

从金沙江干热河谷(元谋段)75种植物的根际土壤中分离鉴定了44种丛枝菌根真菌,分属无梗囊霉属Acaulospora、古孢霉属Archaeospora、内养囊霉属Entrophospora、巨孢囊霉属Gigaspora、球囊霉属Glomus和盾巨孢囊霉属Scutellospora,其中,球囊霉属和无梗囊霉属为金沙江干热河谷中丛枝菌根真菌的优势属。齿状无梗囊霉A．denticulata、刺状无梗囊霉A．spinosa、瘤状无梗囊A．tuberculata,近明球囊霉Glomus claroideum、明球囊霉G．clarum、根内球囊霉G．intraradices、单孢球囊霉Gmonosporum、弯丝球囊霉G．sinuosa是金沙江干热河谷(元谋段)的优势种。金沙江干热河谷土壤中丛枝菌根真菌的孢子密度为5-6400个／100g土壤,平均1504;每个根际土壤中丛枝菌根真菌的物种丰富度1～18种,平均9种。     

都江堰地区丛枝菌根真菌多样性与生态研究

 调查了都江堰地区3个不同生境样地（般若寺、馒头山、龙池）中85种优势及常见植物的丛枝菌根真菌侵染率,其中78种植物（91.8%）被丛枝菌根真菌侵染。同时对其中58种植物根围土壤中丛枝菌根真菌的多样性进行分析,共分离到5属47种丛枝菌根真菌,其中球囊霉属（Glomus）35种,无梗囊霉属（Acaulospora）7种,原囊霉属（Archaeospora）1种,内养囊霉属（Entrophospora）2种,巨孢囊霉属（Gigaspora）2种。无梗囊霉属和球囊霉属是3个样地共有的优势属。光壁无梗囊霉（Acaulospora laevis）是龙池的优势种,而地表球囊霉（Glomus versiforme）是般若寺和馒头山的优势种。丛枝菌根真菌的孢子密度和种的丰度显著受到海拔相关因子影响,同时丛枝菌根真菌的种类组成也受较大影响。乔木砍伐没有显著影响丛枝菌根真菌的孢子密度和种的丰度,同时对种类组成影响也较小。根围土壤中丛枝菌根真菌的孢子密度与根系侵染率之间没有显著相关性（R2=0.024 8）。     

西双版纳地区龙脑香科植物AM真菌的初步研究

 对云南省西双版纳地区17种龙脑香科树种根系丛枝菌根（Arbuscular mycorrhiza, AM）真菌的定居情况进行了调查,并对根围土壤中AM真菌进行了分离和鉴定。结果表明,调查根样均有不同程度的菌根感染,感染率最高可达40%,调查揭示了西双版纳地区龙脑香科植物在自然条件下可形成丛枝菌根。初步从龙脑香科植物根际土壤中分离、鉴定出32种AM真菌,隶属于无梗囊霉属（Acaulospora）、球囊霉属（Glomus）、原囊霉属（Achaeospora）、拟球囊霉属（Paraglomus）和盾巨孢囊霉属（Scutellospora）,其中,无梗囊霉属和球囊霉属真菌为西双版纳地区龙脑香科植物AM真菌优势类群。     

云南金顶铅锌矿区丛枝菌根真菌多样性的研究

对云南金顶铅锌矿区丛枝菌根真菌(Arbuscular mycorrhizal fungi,AMF)资源进行了调查,从32种植物的83个根际土壤样本中分离鉴定出5属36种丛枝菌根真菌,其中无梗囊霉属Acaulospora 5种、内养囊霉属Entrophospora 2种、巨孢囊霉属Gigaspora 1种、球囊霉属Glomus 24种及盾巨孢囊霉属Scutellospora 4种。球囊霉属和无梗囊霉属为金顶铅锌矿区中丛枝菌根真菌的优势属,沃克球囊霉Glomus walkeri是我国的新记录种。近明球囊霉Glomus claroideum、明球囊霉G.clarum、缩球囊霉G.constrictium、地球囊霉G.geosporum、摩西球囊霉G.mossaea、膨胀球囊霉G.pansihalos和疣突球囊霉G.verruculosum是金顶铅锌矿区的优势种;金顶铅锌矿区土壤中丛枝菌根真菌的孢子密度为495-11175个/100g土,平均3368±291(SE,标准误差)个/100g土,每种植物根际土壤中丛枝菌根真菌的物种丰富度为2-20种,平均11.5种;金顶铅锌矿区植物根际土壤中较高的AMF孢子密度和物种丰富度说明AMF对重金属污染具有较强的抗(耐受)性。     

Tuning of electronic properties of one-dimensional cyano-bridged Cu-Ni, Cu-Pd, and Cu-Pt bimetallic assemblies by stereochemistry of ligands

Preparations, XPS and electronic spectroscopy, and magnetism of seven new one-dimensional cyano-bridged coordination polymers, chiral [Cu(RR-chxn)₂][Pd(CN)₄] · 2H₂O (1), [Cu(trans-chxn)₂][M(CN)₄] · 2H₂O (2, 4, and 6 for M = Pd, Ni, and Pt), and [Cu(cis-chxn)₂][M(CN)₄] · 2H₂O (3, 5, and 7 for M = Pd, Ni, and Pt) (RR-chxn = cyclohexane-(1R,2R)-diamine, trans-chxn = racemic trans-cyclohexane-(1,2)-diamine, and cis-chxn = racemic cis-cyclohexane-(1,2)-diamine) have been reported in view of tuning of their electronic properties by stereochemistry of chxn ligands and metal-substitution. Comparison of Cu 2p_1/2 and 2p_3/2 peaks of XPS and broad d-d bands around 18 000 cm⁻¹ of electronic spectra are described systematically for 1-7. Variable-temperature magnetic measurement shows that complexes 1-7 indicate weak antiferromagnetic interactions via cyano-bridges. Because of semi-coordination coupled with pseudo Jahn-Teller elongation and electrostatic interaction for 1, the axial Cu-N coordination bond distances of 2.330(7) and 3.092(8) Å are considerably longer than those of equatorial ones in the range from 2.016(6) to 2.030(6) Å. The former bond distances of 1 are intermediate values among the related Ni (2.324(6) and 3.120(8) Å) and Pt (2.34(1) and 3.09(1) Å) complexes.     

Land,livestock, and livelihoods: Changing dynamics of gender,caste, and ethnicity in a Nepalese Village

Over the past 10 years, Ghusel VDC, Lalitpur District has moved from primarily subsistence agriculture into the wider cash economy aided by the Small Farmers' Development Program (SFDP), which provides credit to farmers mainly for the purchase of buffalo for milk production, and by the National Dairy Corporation, which supports local dairy cooperatives. Analysis reveals that buffalo-keeping and milk sales are increasing the well-being of many households, while at the same time creating new inequalities in gender roles and responsibilities, greater inequities between Brahmin and Tamang residents in Ghusel, and placing pressures on the ecosystem for increased supplies of fodder and fuelwood. Evidence suggests that there is critical, need for attention to the social, and particularly gender-based, implications of maintaining livestock for milk sales and to the ecological underpinnings of this livelihood system.     

Structure and function of S-adenosylhomocysteine hydrolase

In mammals, S-adenosylhomocysteine hydrolase (AdoHcyase) is the only known enzyme to catalyze the breakdown of S-adenosylhomocysteine (AdoHcy) to homocysteine and adenosine. AdoHcy is the product of all adenosylmethionine (AdoMet)-dependent biological transmethylations. These reactions have a wide range of products, and are common in all facets of biometabolism. As a product inhibitor, elevated levels of AdoHcy suppress AdoMet-dependent transmethylations. Thus, AdoHcyase is a regulator of biological transmethylation in general. The three-dimensional structure of AdoHcyase complexed with reduced nicotinamide adenine dinucleotide phosphate (NADH) and the inhibitor (1′R, 2′S, 3′R)-9-(2′,3′-dihyroxycyclopenten-1-yl)adenine (DHCeA) was solved by a combination of the crystallographic direct methods program, SnB, to determine the selenium atom substructure and by treating the multiwavelength anomalous diffraction data as a special case of multiple isomorphous replacement. The enzyme architecture resembles that observed for NAD-dependent dehydrogenases, with the catalytic domain and the cofactor binding domain each containing a modified Rossmann fold. The two domains form a deep active site cleft containing the cofactor and bound inhibitor molecule. A comparison of the inhibitor complex of the human enzyme and the structure of the rat enzyme, solved without inhibitor, suggests that a 17° rigid body movement of the catalytic domain occurs upon inhibitor/substrate binding.     

Chiral Separation of G‐type Chemical Warfare Nerve Agents via Analytical Supercritical Fluid Chromatography

Chemical warfare nerve agents (CWNAs) are extremely toxic organophosphorus compounds that contain a chiral phosphorus center. Undirected synthesis of G‐type CWNAs produces stereoisomers of tabun, sarin, soman, and cyclosarin (GA, GB, GD, and GF, respectively). Analytical‐scale methods were developed using a supercritical fluid chromatography (SFC) system in tandem with a mass spectrometer for the separation, quantitation, and isolation of individual stereoisomers of GA, GB, GD, and GF. Screening various chiral stationary phases (CSPs) for the capacity to provide full baseline separation of the CWNAs revealed that a Regis WhelkO1 (SS) column was capable of separating the enantiomers of GA, GB, and GF, with elution of the P(+) enantiomer preceding elution of the corresponding P(–) enantiomer; two WhelkO1 (SS) columns had to be connected in series to achieve complete baseline resolution. The four diastereomers of GD were also resolved using two tandem WhelkO1 (SS) columns, with complete baseline separation of the two P(+) epimers. A single WhelkO1 (RR) column with inverse stereochemistry resulted in baseline separation of the GD P(–) epimers. The analytical methods described can be scaled to allow isolation of individual stereoisomers to assist in screening and development of countermeasures to organophosphorus nerve agents. Chirality 26:817–824, 2014. © 2014 The Authors. Chirality published by John Wiley Periodicals, Inc.     

Influence of Fluoride on Rat Kidney Antioxidant System: Effects of Methionine and Vitamin E

The aim of the study has been to determine and compare the influence upon the kidney antioxidative system, exercised by administration of vitamin E, and vitamin E in combination with methionine, under conditions of oxidative stress induced by sodium fluoride. The experiment was carried out on Wistar FL rats (adult males) that, for 35 days, were administered water, NaF, NaF with vitamin E, or vitamin E with methionine (doses: 10 mg NaF/kg of body mass/24 h, 3 mg vitamin E per 10 μl per rat for 24 h, 2 mg methionine per rat for 24 h). The influence of administered sodium fluoride and antioxidants upon the antioxidative system in kidney was examined by analyzing the concentration of malondialdehyde (MDA) and the activity of the most important antioxidative enzymes (SOD, total and both its isoenzymes, GPX, GST, GR, and CAT). The studies carried out confirmed the disadvantageous effect of the administered dose of NaF upon the antixodiative system in rats (increase in the concentration MDA, decrease activity of all antioxidative enzymes). The administration of vitamin E increased the activity of studied enzymes with the exception of glutathione reductase GR; it also reduced the procesess of lipid peroxidation. It has been found that combined doses of vitamin E and methionine were most effective in inhibiting lipid peroxidation processes. The results confirmed the antioxidative properties of methionine.     

Reorientation of Microfibrils and Microtubules at the Outer Epidermal Wall of Maize Coleoptiles During Auxin-Mediated Growth

Auxin-mediated elongation growth of isolated subapical coleoptile segments of maize (Zea mays L.) is controlled by the extensibility of the outer cell wall of the outer epidermis (Kutschera et al., 1987). Here we investigate the hypothesis that auxin controls the extensibility of this wall by changing the orientation of newly deposited microfibrils through a corresponding change in the orientation of cortical microtubules. On the basis of electron micrographs it is shown that cessation of growth after removal of the endogenous source of auxin is correlated with a relative increase of longitudinally orientated microfibrils and microtubules at the inner wall surface. Conversely, reinduction of growth by exogenous auxin is correlated with a relative increase of transversely orientated microfibrils and microtubules at the inner wall surface. These changes can be detected 30–60 min after the removal and addition of auxin, respectively. The functional significance of directional changes of newly desposited wall microfibrils for the control of elongation growth is discussed.     

Gamma-glutamylcysteine protects ergothioneine-deficient Mycobacterium tuberculosis mutants against oxidative and nitrosative stress

Mycobacterium tuberculosis (M.tb.), the causative agent of tuberculosis (TB), cannot synthesize GSH, but synthesizes two major low molecular weight thiols namely mycothiol (MSH) and ergothioneine (ERG). Gamma-glutamylcysteine (GGC), an intermediate in GSH synthesis, has been implicated in the protection of lactic acid bacteria from oxidative stress in the absence of GSH. In mycobacteria, GGC is an intermediate in ERG biosynthesis, and its formation is catalysed by EgtA (GshA). GGC is subsequently used by EgtB in the formation of hercynine-sulphoxide-GGC. In this study, M.tb. mutants harbouring unmarked, in-frame deletions in each of the fives genes involved in ERG biosynthesis (egtA, egtB, egtC, egtD and egtE) or a marked deletion of the mshA gene (required for MSH biosynthesis) were generated. Liquid chromatography tandem mass spectrometry analyses (LC-MS) revealed that the production of GGC was elevated in the MSH-deficient and the ERG-deficient mutants. The ERG-deficient ΔegtB mutant which accumulated GGC was more resistant to oxidative and nitrosative stress than the ERG-deficient, GGC-deficient ΔegtA mutant. This implicates GGC in the detoxification of reactive oxygen and nitrogen species in M.tb.     

In vitro studies of the rabbit immune system. IV. Differential mitogen responses of isolated T and B cells.

The mitogenic responses of separated rabbit lymphocyte populations functionally analogous to mouse T and B cells have been tested in vitro. Purified T cells were prepared by passage over nylon wool (NW) and purified B cells prepared by treatment with antithymocyte serum and complement (ATS + C). ATS + C kills 70% of peripheral blood lymphocytes (PBL's) and 50% of the spleen cells while passage over NW yields 40% of the applied PBL's and 5–23% of the applied spleen cells. NW-purified T cells from the spleen or PBL's respond fully to concanavalin A (Con A) but have a reduced response to phytohemaglutinin (PHA) and little or no response to goat anti-rabbit immunoglobulin (anti-Ig). PBL's that survive ATS + C (B cells) are stimulated by anti-Ig but not by Con A or PHA. B cells purified from spleen do not respond to Con A or PHA but will respond to anti-Ig under appropriate conditions. A full spleen B-cell response to anti-Ig required removal of Ig produced by the cultures that blocked anti-Ig stimulation. It is concluded that, for rabbit lymphocytes, Con A and PHA are primarily T-cell mitogens and that anti-Ig is primarily a B-cell mitogen. However, the mitogen response of unfractionated PBL or spleen cell populations indicates an overlap in reactivity. This could be due to cells sharing T and B properties, alteration of cell populations by the fractionation procedures used, or recruitment of one population in the presence of a mitogenic response of the other population.     

八种脑-肠肽侧脑室内注射对大鼠基础胃酸分泌的影响

用乌拉坦麻醉大鼠作急性实验,采用连续灌流胃并收集流出液的方法,观察向侧脑室内注射微量脑-肠肽对大鼠基础胃酸分泌的影响。实验结果如下:(1)雨蛙肽、八肽胆囊收缩素、促甲状腺素释放激素及四肽胃泌素均使总酸排出量增加;(2)生长抑素、胰多肽、P 物质、胰高血糖素则使总酸排出量减少;(3)上述肽类用侧脑室注射的剂量作肌肉注射,除四肽胃泌素也产生明显的刺激胃酸分泌作用外,对胃酸分泌均无明显影响。以上结果提示,脑内的一些肽类可能以神经递质或调制物的方式,参与中枢对胃酸分泌的调节。     

A chromium-tolerant plant growing in Cr-contaminated land

In this paper, a kind of Typhaceae plant species, Typha angustifolia L, with a high tolerance to Cr is described. Experiments were carried out to examine its ability to tolerant Cr and its physiological response. The results showed that there was no difference in growth, plant height, and biomass response to external Cr (VI) between the plants exposed to 100 microM Cr (VI) and control (0 microM), while increasing Cr levels to 200-800 microM induced a significant decrease in plant height and biomass, but no significant injury was detected, even for the plants exposed to 800 microM Cr. Chromium induced significant increases in superoxide dismutase (SOD) and peroxidase (POD) activities. Meanwhile, a significantly positive correlation was found between Cr and Mn or Cu in leaves and roots, respectively. The Cr tolerance of the plant appeared to be associated with the enhancement of SOD and POD activities and the improvement in uptake and translocation of the essential microelements.