Study of the tolerance of Hippochaete ramosissimum to Cu stress

We investigated the tolerance of Hippochaete ramosissimum and the changes in physiological metabolism following exposure to copper using pot experiments and analyzing plant physiology and biochemistry. The results showed that Cu tolerance in Hippochaete ramosissimum varied significantly between different populations; the tolerance of plants living in Cu polluted areas for extended periods of time exceeded that of plants living in unpolluted areas. SOD and POD activities in highly Cu tolerant plants increased noticeably following exposure to Cu. This indicates that maintaining and increasing the two kinds of protective enzyme activities are the primary foundations of plant tolerance. However, no change in CAT activity was demonstrated following Cu exposure. In summary, there existed considerable differences in physiological metabolism between different populations of Hippochaete ramosissimum following exposure to Cu.     

铜官山铜尾矿库植被及土壤酶活性研究

通过野外调查和实验分析,对铜官山铜尾矿库的植被状况和土壤酶活性进行了研究．结果表明,铜宫山铜尾矿库自然定居的高等植物有34种,隶属于16个科33个属,多为1—2年生草本植物,主要隶属于菊科、禾本科和豆科,蔗类植物节节草在尾矿库中也具有较大优势．尾矿库植被形成了节节草+白茅群落、狗牙根+白茅群落及芦苇群落等小群落,但仍以单种植物组成的斑块零散分布为主．对尾矿库土壤酶活性的研究表明,3种土壤酶活性和尾矿库的植被状况具有较强的相关性,且3种酶活性与其相关性表现为脲酶＞蔗糖酶＞过氧化氢酶．建议用脲酶活性作为废弃地复垦的一个指示指标。     

节节草生长对铜尾矿砂重金属形态转化和土壤酶活性的影响

通过盆栽模拟栽培试验,研究了节节草生长对铜尾矿砂重金属形态转化和土壤酶活性的影响。结果表明,节节草生长显著提高了尾矿砂中有机物结合态重金属比例(P0.01),降低了交换态和残渣态重金属比例(P0.05)。土壤过氧化氢酶、脲酶、多酚氧化酶和蔗糖酶活性均随着节节草的生长而不同程度的升高,其中过氧化氢酶和脲酶活性均与植物生长时间呈显著正相关(r过氧化氢酶=0.911,P0.05;r脲酶=0.957,P0.01),多酚氧化酶和蔗糖酶活性在植物生长旺盛期达到峰值,分别是对照组的2.40和2.02倍,随后迅速下降;而磷酸酶活性却显著下降(r磷酸酶=-0.923,P0.05)。土壤酶活性与节节草地下部分干重的相关性大于地上部分;且与土壤有机物结合态重金属的含量呈显著正相关,与交换态和残渣态重金属含量呈显著负相关。节节草生长不仅促进了铜尾矿砂重金属朝螯合态方面转化,有效降低重金属的生物有效性,同时还显著地改善了铜尾矿砂的基质环境和土壤肥力。因此,节节草在铜尾矿废弃地恢复实践中具有较大的应用潜力。     

Study of the tolerance ofHippochaete ramosissimum to Cu stress

Science China Life Sciences - We investigated the tolerance ofHippochaete ramosissimum and the changes in physiological metabolism following exposure to copper using pot experiments and analyzing...     

铜陵市狮子山铜尾矿废弃地生态恢复过程中植被演替规律

通过对铜陵市狮子山铜尾矿废弃地植被的实地调查,探讨了该废弃地的植被状况及其植被恢复过程中的植物群落形成与演替的一般规律与特征.结果表明:目前废弃地入侵、定居植物共49种,隶属于15科38属,主要包括菊科(12种)、禾本科(11种)、豆科(8种)等.极端贫瘠和过高的重金属含量(特别是Cu、Cd,平均超出对照土样的20～30倍)是限制植物在废弃地定居的主要因素.全部植物中,一、二年生草本植物26种,多年生草本植物20种.风播种子和果实是废弃地植物繁殖体的主要来源.尾矿废弃地植物群落形成具有先锋植物的入侵、定居、群聚和竞争等过程,共形成了14种相对稳定的小群落,包括单优势种群落、次优势种群落和共优势种群落三种类型.伴随着尾矿废弃地植物群落的形成与演替,群落中物种丰富度增大,多样性指数呈增加趋势,而群落内植物种综合优势比间的差值趋于减小.     

铜陵市狮子山铜尾矿废弃地生态恢复过程中植被演替规律

通过对铜陵市狮子山铜尾矿废弃地植被的实地调查,探讨了该废弃地的植被状况及其植被恢复过程中的植物群落形成与演替的一般规律与特征。结果表明目前废弃地入侵、定居植物共49种,隶属于15科38属,主要包括菊科(12种)、禾本科(11种)、豆科(8种)等。极端贫瘠和过高的重金属含量(特别是Cu、Cd,平均超出对照土样的20~30倍)是限制植物在废弃地定居的主要因素。全部植物中,一、二年生草本植物26种,多年生草本植物20种。风播种子和果实是废弃地植物繁殖体的主要来源。尾矿废弃地植物群落形成具有先锋植物的入侵、定居、群聚和竞争等过程,共形成了14种相对稳定的小群落,包括单优势种群落、次优势种群落和共优势种群落三种类型。伴随着尾矿废弃地植物群落的形成与演替,群落中物种丰富度增大,多样性指数呈增加趋势,而群落内植物种综合优势比间的差值趋于减小。     

铜处理下节节草耐性机制的探讨

通过盆栽试验研究了外源铜胁迫下节节草对铜的耐性机制。结果表明节节草具有较强的解毒功能,可通过多种途径提高植物对铜的耐受性。钝化根系土壤中Cu2＋的生物有效性,降低土壤中交换态铜含量,阻止过量Cu2＋进入体内;细胞壁及残渣、含核糖蛋白体的细胞溶质部分是结合铜的主要部位,进一步降低了进入体内的铜含量;进入体内的Cu2＋以沉淀或螯合蛋白的形式存在,显著降低铜离子的生物有效性和毒性;SOD和POD在铜处理下节节草细胞活性氧防御机制中起关键作用。     

Comparative morphology of the gametophytes of Equisetum subgenus Hippochaete and the sexual behaviour of E. ramosissimum subsp. debile, (Roxb.) Hauke, E. hyemale var. affine (Engelm.) A.A., and E. laevigatum A. Br.

Gametophytes of Equisetum , subgenus Hippochaete , species E. hyemale, E. ramosissimum, E. laevigatum, E. variegatum and E. scirpoides are morphologically distinct. Lamellae from female branches and the archegonial neck cells provide a range of diagnostic features but antheridia are uniform throughout this subgenus, unlike the subgenus Equisetum , in which antheridial morphology is the most reliable criterion for specific identification of gametophytes. The classification of Equisetum into two subgenera based on sporophytic features is supported by gametophyte morphology: column lamellae and sunken antheridia with two opercular cells occur in Hippochaete whereas plate lamellae and projecting antheridia prevail in subgenus Equisetum. The absence of well-marked discontinuities in gametophyte morphology in Hippochaete reinforces cytologica! and hybridization data indicating that the taxa are more closely interrelated man in the subgenus Equisetum. No differences in gametophyte morphology were detected at the intraspecific level. Neither gametophyte morphology nor sexuality provide any definitive data to support me theory that Hippochaete contains the most primitive extant horsetails.
Sexuality in E. ramosissimum subsp. debile, E. hyemale var. affine and E. laevigatum is far more labile than in other taxa of Equisetum. Both male and female secondary gametophytes may be derived from initially male or female individuals as a result of lamellar proliferation.     

Differential invertase activity and root growth between Cu-tolerant and non-tolerant populations in Kummerowia stipulacea under Cu stress and nutrient deficiency

There has been no study on key enzymes in sucrose cleavage in metallophyte plants so far, which may be crucial for the plants’ root growth and heavy-metal tolerance maintenance. Here, we tested the hypothesis that the roots of copper tolerant plants should manifest a higher activity of acid invertases that are rate-limiting in sucrose catabolism than non-tolerant plants both for supporting growth and for their maintaining tolerance under Cu stress. Two populations of Kummerowia stipulacea, one from an ancient waste heap at a Cu mine, and the other from a non-contaminated site, were used in the experiments. The plants were grown in 1/2-fold (control) or 1/20-fold (nutrient deficiency) Hoagland’ solution, with (Cu stress) or without (control) 10 μmol/L Cu²⁺. Plants from the mine proved to be of Cu tolerance. Cu exposure had a stronger inhibition on root growth and thus resulting in a lower root/shoot ratio in the plants of non-mine population compared to the mine population. Cu exposure showed a stronger inhibition of acid invertase activity of Cu non-tolerant plants than Cu-tolerant plants, while neutral/alkaline invertase was insensitive to Cu. A positive correlation between the activity of acid invertases and the root growth and root/shoot ratio was observed. The results indicated an important role of acid invertases in governing root growth and root/shoot biomass allocation in the plants of mine population. The results also suggested that the higher activities in acid invertases of mine population plants might at least partly associate with the plants’ Cu tolerance, and their higher activities in acid invertases in turn played an role in maintenance of the Cu tolerance by supplying carbon and energy for tolerance mechanisms. In addition, the results showed evidence that neutral/alkaline invertase might play a role in compensating for the depression in sucrose catabolism due to Cu-induced inhibition in acid invertases.     

An experimental study of the reproductive biology and hybridization in the European and North American species of Equisetum

Sporophytc production was investigated in the eleven North American and European species of Equisetum by means of fertilization experiments on both intact and subcultured gametophytes. Comparison of intra- and inter-gametophytic selfing with intergametophytic crossing failed to reveal any evidence of recessive sporophytic lethals, leaky lethals or deleterious recessive genes. Fertilization in Equisetum depends solely on the availability of ripe archegonia. Despite the absence of detectable genetic load in Equisetum , intergametophytic mating is ensured by gametophyte dioecism in the wild. All populations tested were freely interfcrtile indicating a high degree oi genetic con-specihcity, even between North America and Europe. Low sporophyte frequencies in European E. scirpoides are attributed to defective spermatozoids. Polyembryony occurs. Cessation in gametophyte development is mediated by allelopathic compounds liberated from the young sporophytes.
Reciprocal crosses resulted in the synthesis of 12 hybrids (six in subgenus Equisetum and six in subgenus Hippochaete plus abortive zygotes in the cross E. ramosissimum female x E. scirpoides male), 11 of which had previously been reported in nature. No intersubgeneric hybrids were produced, indicating that both subgenera are natural groups only distantly related to one another. The putative wild combinations E. pratense x E. atvense and E. variegatum x E. scirpoides were not synthesized, but a new hybrid from the allopatric E. ramosissimum and E. laevigatum arose. Reciprocal crosses within the subgenus Hippochaete usually yielded equal frequencies of hybrids, but in the subgenus Equisetum the majority of successful crosses were unidirectional. All taxa oi Hippochaete are linked by hybrids whereas in subgenus Equisetum, E. pratense and E. sylvatkum form an isolated pair, Hybridization studies, and evidence from gametophyte morphology support the traditional sectional classification of Equisetum.     

A systems biology approach for the analysis of carbohydrate dynamics during acclimation to low temperature in Arabidopsis thaliana

Low temperature is an important environmental factor affecting the performance and distribution of plants. During the so-called process of cold acclimation, many plants are able to develop low-temperature tolerance, associated with the reprogramming of a large part of their metabolism. In this study, we present a systems biology approach based on mathematical modelling to determine interactions between the reprogramming of central carbohydrate metabolism and the development of freezing tolerance in two accessions of Arabidopsis thaliana. Different regulation strategies were observed for (a) photosynthesis, (b) soluble carbohydrate metabolism and (c) enzyme activities of central metabolite interconversions. Metabolism of the storage compound starch was found to be independent of accession-specific reprogramming of soluble sugar metabolism in the cold. Mathematical modelling and simulation of cold-induced metabolic reprogramming indicated major differences in the rates of interconversion between the pools of hexoses and sucrose, as well as the rate of assimilate export to sink organs. A comprehensive overview of interconversion rates is presented, from which accession-specific regulation strategies during exposure to low temperature can be derived. We propose this concept as a tool for predicting metabolic engineering strategies to optimize plant freezing tolerance. We confirm that a significant improvement in freezing tolerance in plants involves multiple regulatory instances in sucrose metabolism, and provide evidence for a pivotal role of sucrose-hexose interconversion in increasing the cold acclimation output.     

昆虫对植物次生物质的代谢适应机制及其对昆虫抗药性的意义

植物次生物质(plant secondary metabolites)对昆虫的取食行为、生长发育及繁殖可以产生不利影响,甚至对昆虫可以产生毒杀作用。为了应对植物次生物质的不利影响,昆虫通过对植物次生物质忌避取食、解毒代谢等多种机制,而对寄主植物产生适应性。其中,昆虫的解毒代谢酶包括昆虫细胞色素P450酶系（P450s）及谷胱甘肽硫转移酶（GSTs）等,在昆虫对植物次生物质的解毒代谢及对寄主植物的适应性中发挥了重要作用。昆虫的解毒酶系统不仅可以代谢植物次生物质,还可能代谢化学杀虫剂,因而昆虫对寄主植物的适应性与其对杀虫剂的耐药性甚至抗药性密切相关。昆虫细胞色素P450s和GSTs等代谢解毒酶活性及相关基因的表达可以被植物次生物质影响,这不仅使昆虫对寄主植物的防御产生了适应性,还影响了昆虫对杀虫剂的解毒代谢,因而改变昆虫的耐药性或抗药性。掌握昆虫对植物次生物质的代谢适应机制及其在昆虫抗药性中的作用,对于明确昆虫的抗药性机制具有重要的参考意义。本文综述了植物次生物质对昆虫的影响、昆虫对寄主植物次生物质的代谢机制、昆虫对植物次生物质的代谢适应性对昆虫耐药性及抗药性的影响等方面的研究进展。     

铜对节节草生理代谢及抗氧化酶活性的影响

采用盆栽试验方法,研究了重金属Cu对节节草的生理代谢及抗氧化酶活性的影响.结果表明,低浓度Cu(500 mg·kg^-1)处理下节节草生理代谢变化不明显.高浓度Cu(1 000～3 000 mg·kg^-1)处理下,节节草体内叶绿素a和叶绿素b含量均显著下降,叶绿素b的含量仅为对照的43%;可溶性糖含量平均为对照的1/2,细胞膜透性平均高出对照1～2倍,MDA含量平均为对照的1～3倍,表明高浓度Cu胁迫对节节草细胞质膜系统及主要细胞器的结构与功能具有破坏作用.Cu胁迫下节节草抗氧化酶活性随Cu浓度增加而上升,POD和SOD酶活性平均分别增长34.73%和51.55%,且与Cu浓度呈显著正相关(r_POD＝0.978,r_SOD＝0.926,P<0.05).     

自然演替过程中铜尾矿土壤酶活性的变化

铜陵矿区堆放了大量不同时期的铜尾矿,形成大量铜尾矿废弃地,其中的大部分铜尾矿废弃地处于自然生态恢复状态。并形成典型的原生演替系列。为探讨废弃地自然生态恢复中不同演替阶段植物群落变化与土壤酶活性变化的关系,对铜陵3处不同时期弃置的尾矿废弃地进行了调查。随着自然生态系统演替的进行,尾矿中土壤酶活性逐步提高,维管植物群落下尾矿中土壤酶活性〉隐花植物结皮下尾矿中土壤酶活性〉裸地处土壤酶活性;位于植物群落下的尾矿废弃地中脲酶、碱性磷酸酶、过氧化氢酶的活性从表层至下层逐渐降低。不同植物群落对尾矿中土壤酶活性影响有很大差异,位于木贼群落下的尾矿中几种土壤酶的活性高于位于白茅群落和中华结缕草群落下的尾矿中酶的活性。相关分析表明,土壤酶活性与有机质、总N表现出显著的正相关。     

Hydrogen peroxide pre-treatment induces salt-stress acclimation in maize plants

The effect of exogenously applied H2O2 on salt stress acclimation was studied with regard to plant growth, lipid peroxidation, and activity of antioxidative enzymes in leaves and roots of a salt-sensitive maize genotype. Pre-treatment by addition of 1 microM H2O2 to the hydroponic solution for 2 days induced an increase in salt tolerance during subsequent exposure to salt stress. This was evidenced by plant growth, lipid peroxidation and antioxidative enzymes measurements. In both leaves and roots the variations in lipid peroxidation and antioxidative enzymes (superoxide dismutase, ascorbate peroxidase, guaiacol peroxidase, glutathione reductase, and catalase) activities of both acclimated and unacclimated plants, suggest that differences in the antioxidative enzyme activities may, at least in part, explain the increased tolerance of acclimated plants to salt stress, and that H2O2 metabolism is involved as signal in the processes of maize salt acclimation.     

Anatomy and genetic diversity of two populations of Schinus terebinthifolius (Anacardiaceae) from the Tibagi River basin in Paraná, Brazil

Knowledge of the effects of flooding on plant survival is relevant for the efficiency of management and conservation programs. Schinus terebinthifolius is a tree of economic and ecological importance that is common in northeast Brazil. Flooding tolerance and genetic variation were investigated in two riparian populations of S. terebinthifolius distributed along two different ecological regions of the Tibagi River basin. Flooding tolerance was evaluated through the investigation of young plants, submitted to different flooding intensities to examine the morphological and anatomical responses to this stress. The growth rate of S. terebinthifolius was not affected by flooding, but total submersion proved to be lethal for 100% of the plants. Morphological alterations such as hypertrophied lenticels were observed in both populations and lenticel openings were significantly higher in plants from one population. Genetic analysis using DNA samples obtained from both populations showed a moderate degree of genetic variation between populations (13.7%); most of the variation was found within populations (86.3%). These results show that for conservation purposes and management of degraded areas, both populations should be preserved and could be used in programs that intend to recompose riparian forests.     

Heavy metal stress and sulfate uptake in maize roots

ZmST1;1, a putative high-affinity sulfate transporter gene expressed in maize (Zea mays) roots, was functionally characterized and its expression patterns were analyzed in roots of plants exposed to different heavy metals (Cd, Zn, and Cu) interfering with thiol metabolism. The ZmST1;1 cDNA was expressed in the yeast (Saccharomyces cerevisiae) sulfate transporter mutant CP154-7A. Kinetic analysis of sulfate uptake isotherm, determined on complemented yeast cells, revealed that ZmST1;1 has a high affinity for sulfate (Km value of 14.6 +/- 0.4 microm). Cd, Zn, and Cu exposure increased both ZmST1;1 expression and root sulfate uptake capacity. The metal-induced sulfate uptakes were accompanied by deep alterations in both thiol metabolism and levels of compounds such as reduced glutathione (GSH), probably involved as signals in sulfate uptake modulation. Cd and Zn exposure strongly increased the level of nonprotein thiols of the roots, indicating the induction of additional sinks for reduced sulfur, but differently affected root GSH contents that decreased or increased following Cd or Zn stress, respectively. Moreover, during Cd stress a clear relation between the ZmST1;1 mRNA abundance increment and the entity of the GSH decrement was impossible to evince. Conversely, Cu stress did not affect nonprotein thiol levels, but resulted in a deep contraction of GSH pools. Our data suggest that during heavy metal stress sulfate uptake by roots may be controlled by both GSH-dependent or -independent signaling pathways. Finally, some evidence suggesting that root sulfate availability in Cd-stressed plants may limit GSH biosynthesis and thus Cd tolerance are discussed.     

解磷菌株B25的筛选、鉴定及其解磷能力

从安徽省铜陵市铜官山尾矿库木贼根际分离筛选出多株解磷细菌,经过多次筛选纯化获得一株解磷能力较好的菌株B25.采用透射电镜观察和DNA分子技术,确定此菌株属于芽孢杆菌属.研究了解磷菌株B25在培养168 h内的解磷能力、溶液pH值以及菌株生长量的变化情况,并比较了B25在不同条件下的解磷能力.结果表明：解磷菌株B25的解磷能力与溶液pH值之间存在微弱的相关性,在碳源为葡萄糖、初始pH值为7.0、培养温度为30 ℃时解磷效果较好.