Arsenic Uptake and Translocation by Plants in Pot and Field Experiments

A work undertaken by pot and field experiments to assess the suitability of poplars and ferns for the in-situ, phytoextraction, of a dumping site with residues from the roasting process of arseno-pyrite is reported. The main characteristic of this site is the high content of both the As metalloid and heavy metals (e.g., Al, Fe, Cu, Co, Cr, Pb). Two poplar clones (Populus deltoides ‘Dvina’ and Populus x canadensis ‘Orion’) and Pteris vittata (Chinese brake fern) were planted in the contaminated soil both ex situ in pots and in situ. Plant survival, As accumulation in plant tissues, leaf content of pigments, soluble proteins, activity of catalase and SH-groups in both roots and leaves were evaluated during a 24-month study period. Both poplar and fern plants exhibited an increase in the activity of catalase and SH group contents when grown in the presence of pyrite ashes. The results showed that the co-planting system (arsenic-hyperaccumulator fern Pteris vittata and Populus clones) was suitable for phytoextraction of multi-contaminated dumping sites. Agronomic measures such as irrigation, soil tillage and amendments also seem to be necessary for the successful establishment of poplar trees and ferns in contaminated soils in order to enhance plant growth through the improvement of soil conditions.     

傅氏凤尾蕨配子体发育及其无配子生殖的研究

采用光学显微镜对傅氏凤尾蕨（Pteris fauriei Hieron.）的配子体发育进行了研究。傅氏凤尾蕨孢子深褐色,呈四面体形,三裂缝,极面观为钝三角形,赤道面观近半圆形。孢子自播种3～7 d左右开始萌发,萌发类型为书带蕨型。18 d左右发育为丝状体,大约为6～10个细胞长;25 d左右,丝状体可通过顶端细胞或中间细胞分裂产生片状体。播种40～50 d左右,在片状体的侧面产生分生组织,发育成原叶体,发育类型为水蕨型。雄配子体形状不规则,其上可产生精子器。大型原叶体形状较规则,顶端为心形,发育2～3个月左右,在生长点下方产生无性胚芽,进行无配子生殖。此后不久,在胚芽和生长点之间产生导管连接孢子体和配子体。经多次培养表明傅氏凤尾蕨不产生颈卵器,为专性无配子生殖。     

Biological and nutritional aspects involved in fern multiplication

Gametophytes of several species of ferns were mechanically triturated and the resulting homogenates cultured in vitro for propagation purposes. Differences in the time period from spore culture to sporophyte development were perceivable between species. For those species with a fast life cycle and high sporophyte production such as Woodwardia virginica and Dryopteris affinis sp. affinis, homogenization of gametophytes can be considered to be excellent method for propagation, yielding hundreds of sporophytes in a short period of time. Sporophyte formation was inhibited in O. regalis by the succesive application of homogenization to gametophytes regenerated by this technique. The effect of the culture medium composition on fern production was also studied in O. regalis and P. ensiformis gametophytes. In these species, sporophyte formation increased when the gametophytes were cultured in a medium containing water+0.7% agar. Addition of sucrose inhibited gametophyte development and induced their necrosis. The 1/2 dilution of Murashige and Skoog basal medium, without sucrose, favoured leaf expansion in P. ensiformis sporophytes. This revised version was published online in June 2006 with corrections to the Cover Date.     

Positional Shift Between the Vegetative Nucleus and the Generative Cell in Amaryllis Pollen Tube

A modified technique, FITC-tubulin immunofluorescence and DAPI localization to demonstrate simultaneously both the generative cell (GC) and the vegetative nucleus (VN) in the pollen tube under ultra-violet excitation, was developed sucessfully. During the germination of the pollen tube of Amaryllis vittata Ait. the GC and the VN, either being the first one, entered the tube within the first 1—2 h from the pollen grain. However, before the time of GC division, the VN was always positioned distally near the tip of the tube. In case when the GC entered the tube first, then the VN must have a positional shift in order to pass over the GC. The detail processes of positional shift between the GC and the VN were observed. Three basic processes were demonstrated: 1. The anterior end of the VN first reached the vicinity of the posterior attenuated extension of the GC about 2 h following germination forming a temporal physical association. Sometimes their both ends could be inserted into one another for certain extent. 2. The whole VN moved forward and contacted in parallel with the GC until they became twisted together and 3. The VN passed over the GC and greatly elongted lengthwise. Its posterior part became inserted into the anterior end of the GC. The behavior of positional shift between the VN and the GC in the pollen tube seems to be an adjustment of their diameters to fit the narrow tube. A conclusion may be drawn that the rate of movement between the VN and the GC was apparently different during the passage through the tube. Such difference may presumably be accompanied by the independent motive mechanism and structural difference between the VN and GC themselves, which provide their motive force for movement in the tube.     

Pteris multifida,Cortex phellodendri,and probiotics attenuated inflammatory status and immunity in mice with a Salmonella enterica serovar Typhimurium infection

Pteris multifida (PM) and Cortex phellodendri (CP) are medicinal foods used for gastrointestinal protection. Lactic-acid bacteria are probiotics. Salmonella Typhimurium strain ST21-infected mice were used to examine the alleviative effects of two lactic-acid bacteria (LAB) as well as aqueous extracts of PM and CP for a 4-day treatment. CP and LAB decreased fecal ST counts. CP and PM reduced the ST21 count in the blood, intestine, and liver. LAB lowered the ST21 count in the intestine and spleen. CP and LAB decreased the IFN-gamma level; PM lowered the TNF-alpha level; and both LAB and PM reduced the IL-1beta level in serum. PM and CP lowered the IgG level in serum. The data in a macrophage infection model indicate that TNF-alpha was partial involved in this alleviative effects, other mechanisms might be involved. In sum, these novel findings suggest that PM, CP, and LAB probiotics are potential anti-Salmonellae agents.     

Induced apogamous sporophytes inPteris dispar andP. semipinnata,and the meiotic behavior in their sporocytes

Spores ofPteris dispar andP. semipinnata were aseptically cultured in flasks for apogamous sporophyte induction. Calli or cell colonies similar to calli were induced in cultures supplemented with hormones. Sporophytic leaves subsequently developed from them in hormone-free medium and the young sporophytes were raised into plants with sporangia. Since the wild-type plants having 116 chromosomes are tetraploid, the sporophytic plants originating from spores would appear to be diploid (dihaploid). In induced sporophytes ofP. semipinnata, non-homologous chromosomes (58 univalents) were found during the meiotic process in sporocytes. InP. dispar, however, the meiotic cells showed many bivalent chromosomes (maximum 29ll). These results suggest thatP. semipinnata is allotetraploid, whereasP. dispar is autotetraploid.     

凤尾蕨内生真菌的研究Ⅰ——菌种分离及其分类鉴定

首次从凤尾蕨属井栏边草(Pteris multifida)根、茎和叶中分离获得内生真菌共20株,经形态观察,鉴定其中18株分别隶属于8个属。研究结果表明:凤尾蕨不同部位内生真菌的数量、分布、种群及其组成存在差异。     

越南、老挝蕨类植物新记载（3）——凤尾蕨属

通过野外调查和标本研究,报道越南、老挝两地凤尾蕨属Pteris 7个新记载的物种,它们分别是P.argyraea、四川凤尾蕨P.sichuanensis、两广凤尾蕨P.maclurei、 单叶凤尾蕨P.pseudopellucida、 有刺凤尾蕨P.setuloso-costulata、 琼南凤尾蕨P.morii、 栗轴凤尾蕨P.wangiana.     

Proteomic analysis of Pteris vittata fronds: two arbuscular mycorrhizal fungi differentially modulate protein expression under arsenic contamination

Arbuscular mycorrhizae (AM) are the most widespread mutualistic symbioses between the roots of most land plants and a phylum of soil fungi. AM are known to influence plant performance by improving mineral nutrition, protecting against pathogens and enhancing resistance or tolerance to biotic and abiotic stresses. The aim of this study was to investigate the frond proteome of the arsenic hyperaccumulator fern Pteris vittata in plants that had been inoculated with one of the two AM fungi (Glomus mosseae or Gigaspora margarita) with and without arsenic treatment. A protective role for AM fungi colonisation in the absence of arsenic was indicated by the down-regulation of oxidative damage-related proteins. Arsenic treatment of mycorrhizal ferns induced the differential expression of 130 leaf proteins with specific responses in G. mosseae- and Gi. margarita-colonised plants. Up-regulation of multiple forms of glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase, and enolase, primarily in G. mosseae-inoculated plants, suggests a central role for glycolytic enzymes in arsenic metabolism. Moreover, a putative arsenic transporter, PgPOR29, has been identified as an up-regulated protein by arsenic treatment.     

Arsenic uptake and accumulation in fern species growing at arsenic-contaminated sites of southern China: field surveys

Aiming at searching for new arsenic (As) hyperaccumulators, field surveys were conducted at 12 As-contaminated sites located in Guangxi and Guangdong Provinces of southern China. Samples of 24 fern species belonging to 16 genera and 11 families as well as their associated soils were collected and As concentrations in plant and soil samples were determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES). The results show that among 24 fern species, Pteris multifida and P. oshimensis can (hyper)accumulate As in their fronds with high concentrations in addition to P. vittata and P. cretica var. nervosa, which have been previously identified as As hyperaccumulators. Total As concentrations in soils associated with P. multifida and P. oshimensis varied from 1262 to 47,235 mg kg(-1), but the DTPA-extractable As concentrations were relatively low, with a maximum of 65 mg kg(-1). Forty-four of 49 samples of P. multifida collected from five sites and 3 of 13 samples of P. oshimensis collected from one site accumulated over 1000 mg As kg(-1) in their fronds and As concentrations in the fronds were higher than those in the petioles and rhizoids. Although As concentrations in the fronds of P. oshimensis (789 mg kg(-1) averaged, range 301-2142 mg kg(-1)) were comparatively lower than those of P. multifida (1977 mg kg9-1), 624-4056 mg kg(-1)), its high aboveground biomass makes it more suitable for phytoremediating As-contaminated soils. Among all the species in Pteris genus studied, Pteris semipinnata accumulated only very low As concentration in its fronds (8 mg kg(-1), 1-18 mg kg(-1)). Further research is needed to study the differences in As uptake and accumulation among fern species in the same or other genera.