Systematics and evolutionary history of heavy metal tolerant Thlaspi caerulescens in Western Europe: evidence from genetic studies based on isozyme analysis

Thlaspi caerulescens is distributed in Europe on metalliferous and not metalliferous soils. Individuals from populations growing on heavy metal contaminated soils are well known as hyperaccumulators of zinc and cadmium. The taxonomical treatment of subspecies of Thlaspi caerulescens is unsettled. We investigated the degree of genetic variation among 28 populations of Thlaspi caerulescens from Europe with isozyme analysis to compare inter- and intrapopulational diversity. British material from heavy metal contaminated environments recognized as Thlaspi sylvestre and T. occitanicum are quite similar to each other on the level of isozyme polymophisms, but they are more closely related to populations from non-contaminated stands from Scandinavia and Middle Europe than to metallophytes distributed in Continental Europe. Our findings indicate that a taxonomical subdivision of T. caerulescens is not possible and, furthermore, heavy metal tolerance might have evolved twice in populations of Thlaspi caerulescens from different areas. The trait of zinc tolerance and hyperaccumulation is frequently found in numerous relatives of Thlaspi caerulescens, and it is suggested that this trait has been established and manifested in populations from metalliferous sites during postglacial colonization. From Scandinavia only non-metallophytes are known. These populations are very similar to each other on the isozyme level. This fits to the hypothesis that Thlaspi caerulescens was introduced to Scandinavia in recent times by human activity. Despite full self-compatibility we estimated varying outcrossing rates up to 0.88 in the metallophytes and 0.658 in the non-metallophytes depending on population size and structure.     

A comparative study of metal levels in plants from two contrasting lead-mine sites

Summary An investigation into the levels of metals in plants growing on metalliferous soils was carried out. The exchangeable metal concentration of soils from Tyndrum and Trelogan was found to be extremely variable from sample to sample and the influence of soil pH on the exchangeable lead and zinc concentration is discussed. Large differences in heavy metal levels were found between species and may be indicative of different mechanisms of tolerance to lead and zinc excess. Large differences in calcium levels between plant tissues were also found. These may result from the use of calcium in ameliorating lead and zinc toxicity in some species.     

Phylogenetic analysis of the endemic New Caledonian cockroach Lauraesilpha. Testing competing hypotheses of diversification

New Caledonia is a tropical hotspot of biodiversity with high rates of regional and local endemism. Despite offering an ideal setting to study the evolution of endemism, New Caledonia has received little attention compared with the other nearby hotspots, particularly New Zealand. Most studies of the Neocaledonian endemism have been carried out at the regional level, comparing the various groups and species present in New Caledonia but absent in neighboring territories. In addition, remarkably high short‐range endemism has been documented among plants, lizard and invertebrates, although these have usually been done, lacking a phylogenetic perspective. Most studies of Neocaledonian endemism have referred to the geological Gondwanan antiquity of the island and its metalliferous soils derived from ultramafic rocks. Very old clades are thought to have been maintained in refugia and diversified on the metalliferous soils. The present study documents the pattern of diversification and establishment of short‐range endemism in a phylogenetic context using the Neocaledonian cockroach genus Lauraesilpha. Mitochondrial and nuclear genes were sequenced to reconstruct phylogenetic relationships among the species of this genus. These relationships, in the light of the species distribution, do not support the hypothesis that species diversified via an adaptive radiation on metalliferous soils and are not consistent with areas of highest rainfall. Species of Lauraesilpha have similar altitudinal ranges and ecological habits and are short‐range endemics on mountains. What our analysis did reveal was that closely related species are found on nearby or contiguous mountains, and thus these formations probably played the key role establishing short‐range endemism (in association with recent climatic changes). © The Willi Hennig Society 2008.     

The flora and biogeochemistry of the ultramafic soils of Goiás state, Brazil

Major collections of the ultramafic flora of Goiás, central Brazil, were made by Brooks and co-workers in 1988 and 1990. At the time of reports on this material in 1990–1992 much of it had been identified only tentatively and incompletely, but the area was clearly interesting for taxonomic and biogeochemical reasons. Further progress has been made but still only two-thirds of the specimens are identified at the species level. Following a third collection in early 2005, we now have 800 specimens from this area, with chemical analyses of all the plants and of more than 120 representative soil samples. New species have been found, e.g., in Paspalum (Poaceae) and Pterolepis (Melastomataceae). There is a need for more taxonomic work in genera such as Cnidoscolus (Euphorbiaceae), Lippia (Verbenaceae), Turnera and Piriqueta (Turneraceae), and Vellozia (Velloziaceae). Ni hyperaccumulation (>1,000 mg/kg in dry plant matter) has now been found in a total of 79 specimens, representing more than 30 different species. Notable Ni hyperaccumulators include Pfaffia sarcophylla (Amaranthaceae), species of Justicia, Lophostachys and Ruellia (Acanthaceae), Porophyllum (Asteraceae), several species of Lippia (Verbenaceae), Turnera and Piriqueta (Turneraceae), and a possibly new Cnidoscolus (Euphorbiaceae). Ni hyperaccumulation has not been found in plants of the outcrops of Morro Feio or Crominia-Mairipotaba; it seems to be confined to the extensive layered ultramafics of Barro Alto and the Macedo-Niquelandia areas. The distribution of Ni-values in the Brazilian plant collection is different from that found in the Mediterranean and California, where there is a clear distinction between accumulator and non-accumulator plants: in Brazil the distribution is more continuous, and median Ni concentrations are much greater. An ultramafic hill just north of Niquelandia deserves to be protected because of the presence there of many of the hyperaccumulators and species probably endemic to the Goiás ultramafics.     

镍污染土壤植物采矿技术关键过程及其研究进展

植物采矿是利用超积累植物高量吸收土壤中的重金属,并从中提取、冶炼金属产品,在修复污染土壤的同时实现金属的资源化。全世界广泛分布着自然风化的镍污染土壤,植物采矿因其重要的环境、生态及资源价值,被作为一种环境友好且具备经济效益的土壤修复技术,在此类地区具有广阔的应用前景。该植物采矿技术关键过程主要包括超积累植物镍高选择性根际环境响应、植物镍高效吸收转运以及生物质中镍高附加值资源化等过程。近30年,污染土壤中镍的植物采矿已经在美国、阿尔巴尼亚、马来西亚等多个国家进行了野外实践,取得了良好效果。然而,相关技术在我国的研究与应用仍然处于起步阶段。文中通过综述植物采矿技术的关键过程的研究进展,发现其中的瓶颈,为接下来植物采矿的科学研究和技术在全世界推广提供理论基础和技术指导。     

花卉植物应用于污染土壤修复的可行性研究

植物修复是解决污染土壤问题的有效途径之一,而已报道的超积累植物的种类非常有限.如果能从物种繁多的花卉植物中筛选出修复植物,不但能够弥补这一不足,而且还能在美化环境的同时,产生一定的经济效益.从植物修复的重要性和修复植物的筛选出发,概括了修复植物的判断标准及基本特征.通过描述花卉植物资源及其在环境保护中的作用,列举花卉植物与其它植物相比的优势,分析花卉植物的耐性、积累性和修复类型,探讨花卉植物应用于污染土壤修复实践的可行性.从花卉中筛选超积累植物,将为污染土壤的修复工作提供的生物材料.     

Do metal-rich plants deter herbivores? A field test of the defence hypothesis

Some plant species growing on metalliferous soils are able to accumulate heavy metals in their shoots up to very high concentrations, but the selective advantage of this behaviour is still unknown. The most popular hypothesis, that metals protect plants against herbivores, has been tested several times in laboratory conditions, with contradictory results. We carried out the first large-scale test of the defence hypothesis in eight natural populations of the model Zn hyperaccumulator Thlaspi caerulescens J. and C. Presl (Brassicaceae). In two climatic regions (temperate, Belgium–Luxembourg, and Mediterranean, southern France), we worked in metalliferous and in normal, uncontaminated environments, with plants spanning a wide range of Zn concentrations. We also examined the importance of glucosinolates (main secondary metabolites of Brassicaceae) as antiherbivore defences. When exposed to natural herbivore populations, T. caerulescens suffered lower herbivory pressures in metal-enriched soils than in normal soils, both in Belgium–Luxembourg and in southern France. The trapping of gastropods shows an overall lower population density in metalliferous compared to normal environments, which suggests that herbivory pressure from gastropods is lower on metalliferous soils. In addition, foliar concentration of glucosinolates was constitutively lower in all populations from metal-enriched soils, suggesting that these have evolved towards lower investment in organic defences in response to lower herbivory pressure. The Zn concentration of plants had a protective role only for Belgian metallicolous plants when transplanted in normal soils of Luxembourg. These results do not support the hypothesis that Zn plays a key role in the protection of T. caerulescens against enemies. In contrast, glucosinolates appear to be directly involved in the defence of this hyperaccumulator against herbivores.     

Plasmodesmata and plant viruses. A centenary story.

The passage of plant viruses from a cell to adjacent ones remained for a long time an unexplained event. Only during the thirties did Samuel and other plant virologists put forward the hypothesis that the passage occurred through plasmodesmata, i.e. those protoplasmic connections between plant cells described since the late 19th century. A direct relation between viruses and plasmodesmata was first demonstrated by electron microscopy during the late 1960s by Esau and co-workers, and then widely confirmed. The mechanism of the passage was investigated in depth starting from the 1970s, and research received a remarkable impulse after that a well-defined model of plasmodesmata had been obtained thank, in particular, to work of the Robards' and Gunning's groups. In this context, the discovery of the polycystronic functionality of the viral genomes was fundamental. A protein coded by tobacco mosaic virus, discovered in 1982 independently by the Soviet group of Atabekov and the American group of Zaitlin, was demonstrated to be indispensable for the transport of virus infection from cell to cell through plasmodesmata. Elegant investigations on this 'movement protein' demonstrated that it actually increases the permeability of plasmodesmata. The relation between viruses and plasmodesmata is one of the most interesting and investigated theme of research, which is receiving much attention from plant virologists, physiologists and molecular biologists. The current status of knowledge still presents unsolved questions, and the story is far from over.     

The influence of cadmium,copper, lead,and zinc on the distribution and evolution of metallophytes in the British Isles

Mine spoils and other soils contaminated with cadmium, copper, lead and zinc show natural colonization by species which have strategies of avoidance or tolerance of metal toxicities. The distribution of plants on such substrata in the British Isles is examined in the light of present knowledge of such strategies. Evolutionary processes mediating the selection of tolerant individuals and ecotypic differentiation of adapted populations on metalliferous soils are considered. Other factors determining which species can and which cannot evolve tolerance include constitutional differences in species sensitivity to toxic metals, and phenotypic (environmentally-induced) tolerances. The importance of constitutional properties and phenotypic responses in providing explanations for plant distribution on metalliferous soils is assessed.     

A comparative study on population development patterns of Sogatella furcifera between tropical and subtropical areas

The White-backed Planthopper (WBPH), Sogatella furcifera (Horváth (Hemiptera: Delphacidae)) has been the most serious pest threatening rice production in Asia since the late 1970s. A series of field experiments using the same research protocol was carried out to compare the effects of main environmental factors on population development of WBPH in tropical (Philippines) and subtropical (China) areas in 2010–2012 and to provide further evidences of ecological mechanisms involved that cause frequent outbreak in subtropical rice. Outcomes showed that WBPH population in subtropical area could be characterized as the higher population growth rates and higher peak densities. The average growth rate (116.60 ± 46.16) in subtropical area was significantly higher than that in tropical area (24.02 ± 11.25). The higher realized fecundity in subtropical area indicated that the higher growth rates and higher peak densities were mainly related to the poor natural regulating forces in subtropical area. Our results showed that resistant variety could significantly reduce the peak density in subtropical areas, but not in tropical areas. We inferred that the reason for not detecting the effect of resistant variety in tropical area was due to the dominant controlling effects provided by natural enemies, which means that the natural regulating effect in tropical area was strong enough to disguise the effects of resistant variety. The significant interactions between plant resistance and location demonstrated that integration of natural enemies and use of plant resistance could play important roles for reducing outbreak frequency of WBPH effectively in subtropical rice.     

Vegetation and soil and plant chemistry on ultramafic rocks in the tropical Far East

The tropical Far East has many outcrops of ultramafic rock including very large areas in Sulawesi (c. 8000 km²) and New Caledonia (c. 5500 km²). The outcrops occur under several different climates, and give rise to a range of soils, the characteristics of which are reviewed. The vegetation on them is very varied. Under the same climate one can find grassland, scrub, and both short and tall rain forests. The variation in species richness on the ultramafics is difficult to explain. The degree of endemism varies too; it is probably less dependent on soil characteristics than on historical factors. The causes of the various unusual types of vegetation on ultramafic outcrops are discussed. It is possible that the somewhat dwarfed forests result from a shortage of one or more major nutrients or from very high soil Mg/Ca quotients or high Ni concentrations. The distinct ‘maquis’ vegetation of New Caledonia, and probably ultramafic scrub elsewhere, has evolved in relation to not only the soil chemical factors just listed but also periodic fire and varying degrees of drought. Fires are certainly more important than was once thought and the adverse soil factors may have a role in delaying recolonisation. The plant chemistry is notable for the presence of species which hyperaccumulate certain elements, notably Ni. This phenomenon is discussed in relation to its ecological importance, which may be protection of the hyperaccumulators against herbivores. The need for a conservation policy for the ultramafic areas is stressed, and mention is made of the restoration work on sites damaged by nickel mining in New Caledonia.     

Effects of selenium hyperaccumulation on plant-plant interactions: evidence for elemental allelopathy?

? Few studies have investigated plant-plant interactions involving hyperaccumulator plants. Here, we investigated the effect of selenium (Se) hyperaccumulation on neighboring plants. ? Soil and litter Se concentrations were determined around the hyperaccumulators Astragalus bisulcatus and Stanleya pinnata and around the nonhyperaccumulators Medicago sativa and Helianthus pumilus. We also compared surrounding vegetative cover, species composition and Se concentration in two plant species (Artemisia ludoviciana and Symphyotrichum ericoides) growing either close to or far from Se hyperaccumulators. Then, Arabidopsis thaliana germination and growth were compared on soils collected next to the hyperaccumulators and the nonhyperaccumulators. ? Soil collected around hyperaccumulators contained more Se (up to 266 mg Se kg(-1) ) than soil collected around nonhyperaccumulators. Vegetative ground cover was 10% lower around Se hyperaccumulators compared with nonhyperaccumulators. The Se concentration was higher in neighboring species A. ludoviciana and S. ericoides when growing close to, compared with far from, Se hyperaccumulators. A. thaliana showed reduced germination and growth, and higher Se accumulation, when grown on soil collected around Se hyperaccumulators compared with soil collected around nonaccumulators. ? In conclusion, Se hyperaccumulators may increase the surrounding soil Se concentration (phytoenrichment). The enhanced soil Se contents around hyperaccumulators can impair the growth of Se-sensitive plant species, pointing to a possible role of Se hyperaccumulation in elemental allelopathy.     

Local Adaptation of Metallicolous and Non‐Metallicolous Anthyllis vulneraria Populations: Their Utilization in Soil Restoration

Restoration of metalliferous mine soils requires using plant species tolerant to high metal concentrations and adapted to nutrient‐poor soil. Legumes can increase plant productivity through N₂‐fixation, but they are often scarce in metalliferous sites. We examined survival, growth, and tolerance of four populations of a legume, Anthyllis vulneraria, from two metalliferous (MET) Zn‐Pb mine sites, Avinières (AV) ([Zn‐EDTA] = 26,000 mg/kg) and Eylie (EY) ([Zn‐EDTA] = 4,632 mg/kg), and two non‐metalliferous (NMET) sites located in the south of France with the aim to select the most appropriate populations for restoration of mined soils. In a common garden experiment, plants from each population were reciprocally grown in soil from the provenance of each population. The two NMET populations exhibited high mortality and low growth rates in soil from the mined sites. The AV MET exhibited a high growth rate in metalliferous soils, but showed high mortality in non‐metalliferous soils. The growth of the EY MET was very low in the AV‐contaminated soil, but was the highest of all populations in moderately and non‐metalliferous soils. Plants from the AV MET population showed a high growth and survival in metalliferous soil and would be appropriate in the restoration of metal‐contaminated sites (>30,000 mg Zn kg^?1). The EY MET population would be adapted to the restoration of moderate metal‐contaminated soils (<30,000 mg Zn kg^?1). Taking into account the broad distribution of A. vulneraria, these two populations could be suitable for the restoration of derelict mine sites in mediterranean and temperate regions of Europe and North America.     

Determinants of scientific output: an in-depth view of the productivity of tropical botanist and conservationist, Luis Diego Gómez Pignataro

Bibliometric studies have found that male researchers have their greatest productivity around the age of 40, that female researchers produce less than their male colleagues, that incentives for collaboration are slow to affect productivity and that, just like humans, research institutes become larger, less productive, more expensive to maintain and less able to raise money as they grow old. Almost invariably, these conclusions come from statistical studies of large numbers of European and American scientists, and there are practically no studies about tropical researchers. We present an in-depth analysis of the productivity of an internationally recognized tropical botanist and conservationist, Luis Diego Gómez Pignataro, based on the totality of his published work and on our own knowledge, as co-workers and friends, of the life frame in which that scientific output was produced. His life output departs from the expected pattern in that he had the highest productivity before reaching the expected peak productivity age, and that when he reached it his productivity fell and never recovered. Furthermore, marriage did not produce the expected fall in productivity. A close analysis of his life indicates that in the middle of his career he switched to intense teaching and conservation activities, and this better explains why his output of scientific research articles was low afterwards. This switch may occur in other tropical scientists.     

Tropical forest communities in southeastern Mexico

A phytosociological study was carried out along a 450 kmtransect in tropical southeastern Mexico in order to identify plantcommunities.Five major plant communities were distinguished and described:Those communities reflect preference of different environmentalfactorssuch as soils, precipitation and local relief. Further, the major threats(hurricanes, fires, agriculture) to the vegetation of the study areaare discussed.     

我国土壤重金属污染植物吸取修复研究进展

我国从上世纪90年代中后期开始土壤重金属（含类金属砷）污染的植物吸取修复研究及技术探索,先后发现了一批具有较高研究价值和应用前景的铜、砷、镉、锰等重金属的积累或超积累植物,并从重金属耐性和超积累生理机制、植物吸取修复的根际过程与机制、吸取修复强化措施和修复植物处置与资源化利用等方面进行了研究,同时开展了植物吸取修复技术的示范与应用,已有一些较成功的植物修复工程应用案例,使我国重金属污染土壤植物修复技术,尤其是植物吸取修复技术在国际上产生了较强的影响力。本文就近年来我国土壤重金属污染植物吸取修复研究进展进行了综述,并对今后的发展趋势进行了展望。     

Aluminum hyperaccumulation in angiosperms: A review of its phylogenetic significance

Aluminum phytotoxicity and genetically based aluminum resistance has been studied intensively during recent decades because aluminum toxicity is often the primary factor limiting crop productivity on acid soils. Plants that grow on soils with high aluminum concentrations employ three basic strategies to deal with aluminum stress. While excluders effectively prevent aluminum from entering their aerial parts over a broad range of aluminum concentration in the soil, hyperaccumulators take up aluminum in their aboveground tissues in quantities above 1000 ppm; that is, far exceeding those present in the soil or in the nonaccumulating species growing nearby. In between these two extremes are indicator species, representing intermediate responses. A list of aluminum hyperaccumulators in angiosperms is compiled on the basis of data in the literature. Aluminum hyperaccumulators include mainly woody, perennial taxa from tropical regions. Recent molecular phylogenies are used to evaluate the systematic and phylogenetic implications of the character. As was hypothesized earlier, our preliminary conclusions support the primitive status of aluminum hyperaccumulation. According to the APG classification system, this phytochemical character is found in approximately 45 families, which belong largely to the eudicots. Aluminum hyperaccumulators are particularly common in basal branches of fairly advanced groups such as rosids (Myrtales, Malpighiales, Oxalidales) and asterids (Cornales, Ericales, Gentianales, Aquifoliales), but the character has probably been lost in the most derived taxa. The feature is suggested to characterize approximately 18 families (e.g., Anisophylleaceae, Cunoniaceae, Diapensiaceae, Memecylaceae, Monimiaceae, Rapateaceae, Siparunaceae, Vochysiaceae, and several monogeneric families). In 27 other families, aluminum hyperaccumulation is restricted to subfamilies, tribes, or genera. Further analyses of a broader range of taxa are needed to examine the origin and taxonomic significance of aluminum hyperaccumulation in several clades. Aluminum hyperaccumulation provides an evolutionary model system for the integration of different biological disciplines, such as systematics, ecology, biogeography, physiology, and biochemistry. Therefore, multidisciplinary approaches are needed to make further progress in understanding the biology of aluminum hyperaccumulators.     

重金属污染土壤植物修复基本原理及强化措施探讨

阐述了植物修复的基本概念及主要作用方式 ,并从土壤中重金属存在形态 ,植物对重金属吸收、排泄和积累以及植物生物学特性与植物修复的关系等方面讨论了重金属污染土壤植物修复的基本原理及局限性和限制性因素 ,从超富集植物性能强化和技术强化两方面探讨了植物修复的强化措施 ,并指出与现代化农业技术相结合是植物修复重金属污染土壤大规模商业应用的一条捷径     

Phytoremediation efficiency OF CD by Eucalyptus globulus transplanted from polluted and unpolluted sites

The capacity of plants to uptake heavy metals from contaminated soils has shown great phytoremediation potential. The development, resistibility and Cd extraction of Eucalyptus globulus individuals from metalliferous and clean sites in different years were analyzed under a specific environment. Eucalyptus globulus planted in Guiyu for phytoremediation or cultivated in an uncontaminated, natural environment for economic purposes were transplanted to Yuecheng town, which, in recent years, has been involved in the e-waste dismantling and recycling business, to compare the phytoremediation efficiency of Eucalyptus globulus trees grown in different environments. Trees cultivated in polluted areas can remove far more Cd and Hg from the contaminated soil than the individuals from clean soils because metalliferous Eucalyptus globulus can produce more biomass and uptake more heavy metals than nonmetalliferous plants per year. As polluted environments negatively affect the growth of plants, we speculated that the phytoremediation efficiency of metalliferous Eucalyptus globulus should decrease over time and that nonmetalliferous trees should adapt to the local environment.