Variations in Metal Tolerance and Accumulation in Three Hydroponically Cultivated Varieties of Salix integra Treated with Lead

Willow species have been suggested for use in the remediation of contaminated soils due to their high biomass production, fast growth, and high accumulation of heavy metals. The tolerance and accumulation of metals may vary among willow species and varieties, and the assessment of this variability is vital for selecting willow species/varieties for phytoremediation applications. Here, we examined the variations in lead (Pb) tolerance and accumulation of three cultivated varieties of Salix integra (Weishanhu, Yizhibi and Dahongtou), a shrub willow native to northeastern China, using hydroponic culture in a greenhouse. In general, the tolerance and accumulation of Pb varied among the three willow varieties depending on the Pb concentration. All three varieties had a high tolerance index (TI) and EC50 value (the effective concentration of Pb in the nutrient solution that caused a 50% inhibition on biomass production), but a low translocation factor (TF), indicating that Pb sequestration is mainly restricted in the roots of S. integra. Among the three varieties, Dahogntou was more sensitive to the increased Pb concentration than the other two varieties, with the lowest EC50 and TI for root and above-ground tissues. In this respect, Weishanhu and Yizhibi were more suitable for phytostabilization of Pb-contaminated soils. However, our findings also indicated the importance of considering the toxicity symptoms when selecting willow varieties for the use of phytoremediation, since we also found that the three varieties revealed various toxicity symptoms of leaf wilting, chlorosis and inhibition of shoot and root growth under the higher Pb concentrations. Such symptoms could be considered as a supplementary index in screening tests.     

Proteolytic activity in the genus ficus

The latices of only 13 of a total of 46 species of Ficus examined contained appreciable proteolytic activity. Therefore, high proteolytic activity in the latex is not a distinguishing feature of the genus. The latex of F. stenocarpa had the highest specific activity followed closely by the latices of F. carica and F. glabrata. Latices of 6 species of Ficus were examined by chromatography on CM-cellulose and compared with the results obtained for 9 varieties of F. carica. All of the latices were found to contain multiple proteolytic enzymes. Chromatographically, the multiple enzyme components of the several varieties of F. carica were more similar than those of the several species examined. The latices of 16 varieties of F. carica were all different as determined by free boundary electrophoresis although the specific proteolytic activity of the latices was reasonably constant.     

Sterols and triterpenols in latex and cultured tissues of Euphorbia pulcherrima

The sterol and triterpenol constituents of Euphorbia pulcherrima latex and cultured callus tissues were examined by GLC and mass spectrometry. Latex extracts from different varieties contained sitosterol, β-amyrin, germanicol, cycloartenol, β-amyrin acetate, and germanicol acetate. Capillary GC profiles of these varieties indicated that the triterpene content was essentially identical for examined latices. Cultured tissues derived from petioles and stem internodes synthesized only sitosterol in significant quantities, although trace amounts of several sterols that occur in latex were also detected in cultured tissues. This study supports the interpretation that the pattern of triterpene synthesis in the laticifer of the normal plant is a highly controlled and stable phenomenon among varieties of this species.     

Species delimitation and hybridization history of a hazel species complex

Background and AimsHybridization increases species adaptation and biodiversity but also obscures species boundaries. In this study, species delimitation and hybridization history were examined within one Chinese hazel species complex (Corylus chinensis–Corylus fargesii). Two species including four varieties have already been described for this complex, with overlapping distributions.MethodsA total of 322 trees from 44 populations of these four varieties across their ranges were sampled for morphological and molecular analyses. Climatic datasets based on 108 geographical locations were used to evaluate their niche differentiations. Flowering phenology was also observed for two co-occurring species or varieties.Key ResultsFour statistically different phenotypic clusters were revealed, but these clusters were highly inconsistent with the traditional taxonomic groups. All the clusters showed statistically distinct niches, with complete or partial geographical isolation. Only two clusters displayed a distributional overlap, but they had distinct flowering phenologies at the site where they co-occurred. Population-level evidence based on the genotypes of ten simple sequence repeat loci supported four phenotypic clusters. In addition, one cluster was shown to have an admixed genetic composition derived from the other three clusters through repeated historical hybridizations.ConclusionsBased on our new evidence, it is better to treat the four clusters identified here as four independent species. One of them was shown to have an admixed genetic composition derived from the other three through repeated historical hybridizations. This study highlights the importance of applying integrative and statistical methods to infer species delimitations and hybridization history. Such a protocol should be adopted widely for future taxonomic studies.     

Morphometric analysis of varieties of Acacia caven: (Leguminosae, Mimosoideae): Taxonomic inferences in the context of other Argentinean species

The aims of this study were to evaluate the degree of morphological differentiation between six varieties of Acacia caven and to examine their taxonomic validity in the context of other Argentinean species of the genus. To accomplish these purposes, morphological traits have been analyzed using multivariate methods (non parametric ANOVA, phenetic analysis and principal component analysis) on the varieties of A. caven and other six species of the genus, represented in Argentina. The phenogram obtained showed two principal clusters, one grouping all the species of subg. Acacia and the other grouping the species of subg. Aculeiferum. This result agreed with Vassal's infrageneric classification. However, the results of the principal PCA gathered the seven species here included in three groups, which were consistent with Bentham's infrageneric treatment. The ANOVA method indicated that most of the morphometric characters used were statistically sound for differentiation between varieties of A. caven. Further studies, including more species and characters, must be performed in order to clarify the position of Acacia boliviana and the relationships between A. caven and A. curvifructa.     

Thermophilic and thermotolerant fungi in the desert soils of Saudi Arabia

Forty-eight thermophilic and thermotolerant species in addition to 5 varieties which belong to 24 genera were collected from desert soils in Saudi Arabia on glucose-(22 genera and 38 species + 5 varieties), cellulose-(15 genera and 27 species + 4 varieties) and 40% sucrose-Czapek's agar plates (13 genera and 26 species + 4 varieties) at 45 °C. The most frequent species were as follows: Aspergillus fumigatus, A. terreus, Humicola grisea var. thermoidae and Chaetomium thermophile var. copropile on glucose-; A. fumigatus, C. thermophile var. copropile, A. terreus, A. nidulans and C. thermophile var. dissitum on cellulose-; and A. fumigatus and A. terreus on 40% sucrose-Czapek's agar plates. Sixteen species and 4 varieties were particularly thermophilic and these were A. fumigatus, H. grisea var. thermoidae, H. insolens, H. lanuginosa, C. thermophile var. copropile, C. thermophile var. dissitum, C. virginicum, M. pusillus, S. thermophila, S.? pulverulentum, T. thermophilus, T.? emersoni, T. aurantiacus, T. thermophila, M. pulchella var. sulfurea, M. albomyces, ?A. terrestris, C. pruinosum, T. thermophila and P. thermophila. The remaining species showed different degrees of thermotolerant (32 species + 1 variety).     

Recombination of mitochondrial DNAs following transmission of mitochondria among incompatible strains of black Aspergilli

Successful intra- and interspecific mitochondrial transfers were performed by polyethylene glycol (PEG)-induced protoplast fusion among incompatible strains belonging to the Aspergillus niger species aggregate. The mitochondrial DNAs (mtDNAs) of the strains examined were of three main types based on their restriction fragment length polymorphism (RFLP) profiles. mtDNA types 1 and 2 correspond to A. niger and A. tubingensis species, respectively, while type 3 is represented by some Brazilian wild-type isolates (possibly a distinct species or subspecies). mtDNA types 1 and 2 could be further divided into several subgroups (1a–1e and 2a–2f?). All these strains, representing different RFLP groups or subgroups, were fully incompatible with respect to nuclear complementation. The transfer experiments were carried out under selection pressure, using a mitochondrial oligomycin-resistant mutant of mtDNA type 1a as donor. Following fusion mitochondrial oligomycin-resistant progenies were recovered in the presence of oligomycin by selecting for the nuclear phenotypes of the oligomycin-sensitive recipient strains. All attempted transfers were successful, and resulted in different varieties of resistant recombinant mitochondrial progenies at various frequencies. Within the group of strains of mtDNA type 1, the transfer of oligomycin-resistant mitochondria resulted in the appearance of a single recombinant type of RFLP profile in each case. The recombination events were more complex when the transfer of oligomycin resistance occurred between strains representing different species (mtDNA groups 1a→2 and 1a→3). A great variety of recombinant mtDNA RFLP profiles appeared. Explanation for this phenomenon are discussed on the basis of preliminary physical mapping data.     

Molecular Diversity in Indian Tobacco Types as Revealed by Randomly Amplified DNA Polymorphism

During the past five decades, a large number of tobacco varieties have been developed for different end uses in India through pure line selection from local land races, mutation breeding, and hybridization involving local selections and exotic introductions followed by pedigree selection. No systematic effort has been made to understand the existing diversity pattern in these varieties, which is crucial to define future breeding strategy in this important commercial crop. We characterized 46 varieties belonging to 10 different manufacturing tobacco types cultivated under different agro-climatic conditions in India along with two wild species of Nicotiana using 40 arbitrary primers in RAPID. The level of polymorphism among the varieties of N. tabacum was 59.4%, which was more than double the level observed in the other cultivated species N. rustica (25.2%). A broader range (0.64 to 0.94) of pair wise similarity measures in N. tabacum than in N. rustica (0.83 to 0.92) reflected the more diversified breeding efforts in the major cultivated species. The two wild species namely, N. glutinosa and N. gossei clustered separately from the two cultivated species. Molecular classification of the varieties corresponded largely with their manufacturing trait and parentage. RAPID markers provided sufficient resolution to distinguish among closely related tobacco types. Nine RAPID markers were found conserved across all the varieties and species. The markers found specific to the varieties can be used in correct identification of the carrier genotypes in trade and commerce. This is the first report on the molecular diversity analysis of Indian tobacco.     

The mechanism of pollinator specificity between two sympatric fig varieties: a combination of olfactory signals and contact cues

Background and Aims

Pollinator specificity facilitates reproductive isolation among plants, and mechanisms that generate specificity influence species boundaries. Long-range volatile attractants, in combination with morphological co-adaptations, are generally regarded as being responsible for maintaining extreme host specificity among the fig wasps that pollinate fig trees, but increasing evidence for breakdowns in specificity is accumulating. The basis of host specificity was examined among two host-specific Ceratosolen fig wasps that pollinate two sympatric varieties of Ficus semicordata, together with the consequences for the plants when pollinators entered the alternative host variety.

Methods

The compositions of floral scents from receptive figs of the two varieties and responses of their pollinators to these volatiles were compared. The behaviour of the wasps once on the surface of the figs was also recorded, together with the reproductive success of figs entered by the two Ceratosolen species.

Key Results

The receptive-phase floral scents of the two varieties had different chemical compositions, but only one Ceratosolen species displayed a preference between them in Y-tube trials. Specificity was reinforced at a later stage, once pollinators were walking on the figs, because both species preferred to enter figs of their normal hosts. Both pollinators could enter figs of both varieties and pollinate them, but figs with extra-varietal pollen were more likely to abort and contained fewer seeds. Hybrid seeds germinated at normal rates.

Conclusions

Contact cues on the surface of figs have been largely ignored in previous studies of fig wasp host preferences, but together with floral scents they maintain host specificity among the pollinators of sympatric F. semicordata varieties. When pollinators enter atypical hosts, post-zygotic factors reduce but do not prevent the production of hybrid offspring, suggesting there may be gene flow between these varieties.     

Local Knowledge,Use and Management of Ethnovarieties of <Emphasis Type="Italic">Araucaria angustifolia</Emphasis> (Bert.) Ktze. in the Plateau of Santa Catarina,Brazil

This study examines the human use and management of Araucaria angustifolia ethnovarieties from Santa Catarina, Brazil, and contributes to what is known about the ethnobotany of Araucaria species. The available literature on varietal differences of A. angustifolia is somewhat divergent, and there are currently no ethnobotanical studies on the intraspecific variation and management of this species. The study examined local knowledge and sociocultural and economic values of A. angustifolia varieties to understand how the varieties are managed and how management practices are influencing the conservation of the species. Semi-structured interviews were conducted with 33 informants (identified using the snowball method) in the Painel and Urubici municipalities. Participants identified 12 local varieties, four of which were cited by more than one informant. Characteristic differences include size, color and flavor of the nut-like seeds (pinhão), and most importantly, season of maturation of the cone. The “Caiová” variety was preferred for its bigger, firmer, and sweeter seeds that are considered easier to peel and last longer in storage. Even though there is some interest in developing management practices that favor some varieties in order to guarantee year-round production, seedlings are commonly removed. This management practice is most likely a response to current regulations that prohibit cutting down adult trees. The results of this study have important implications for the relationship between the knowledge of A. angustifolia practices and the current legal framework that protects this species. A more detailed understanding of the relevant ethnobotanical knowledge is required in order to establish the best practices for sustainable use of A. angustifolia and its varietal diversity and to support the communities that depend on this species as a resource.     

Seed Storage Protein Profiles of Seven Indian Wheat (Triticum aestivum L.) Varieties

Seed storage protein profiles, Including triticin, gliadin and glutenin, of seven Indian wheat varieties were Investigated using sodium dodecyl sulfate-polyacrylamide gel eletrophoresis (50S-PAGE). A strategy was developed for half-seed analysis of the three seed storage protein classes. The results are presented In the form of a key for Identification of these varieties based on their seed protein composition. A minimum of 10 seeds of each variety were analysed to check for possible intravarietal heterogeneity, and all the varieties except HUW-12 were homogeneous. The HUW-12 was a mixture of two ‘biotypes’ with respect to the low molecular weight (LMW) glutenin subunits coded by the Glu-A3 locus. The varieties were also analysed for the presence of rye chromatin using a rye-specific repetitive DNA probe (pAW-161), and two of the recently released varieties HUW-206 and HUW-318 were found to possess rye chromatin. Based on the DNA dot-blot results, presence of rye secalins and the absence of chromosome 1 B-speclflc gliadlns It was concluded that these two varieties possess 1BL-1RS wheat-rye translocation. Both of these varieties also have high molecular weight (HMW) glutenin subunits 5 + 10 which may be necessary for compensating the loss of dough strength associated with the wheat-rye translocations.     

黑龙江省七星河湿地硅藻植物的初步研究

报道了2004年对黑龙江省七星河湿地国家级自然保护区的硅藻门植物研究的结果,共发现155个分类单位,包括113种39变种3变型,分别隶属于2纲6目9科26属,其中中国新记录2种2变种1变型共计5个分类单位,初步分析了七星河湿地硅藻植物群落的种类组成及生态类型,大部分的硅藻属于普生种类,同时出现了一些喜酸种类如：Eunotia pectinalis var. ventralis(Ehr.)Hust., Tabellaria flocculosa(Roth) Kütz.,Gomphonema augur Ehr.,Navicula subtilissima Cl.等,还有少量的嗜碱性种类出现。     

Tennessee plant species screened for renewable energy sources

The USDA Northern Regional Research Center (NRRC) has previously studied chemical and botanical characteristics of about 1,000 plant species in efforts to identify potential new plant sources for industrial raw materials. For this report, an additional 51 species were collected from Tennessee and studied. Above-ground plant samples were analyzed for yields of oils, polyphenols, hydrocarbons, protein, and ash. Oils were examined for the presence of seven classes of lipids and analyzed for yields of fatty acids and unsaponifiable matter. Hydrocarbons were examined for the presence of rubber, gutta, and waxes. Rubber and gutta were analyzed for average molecular weight (MW) and MW distribution. Chemical and botanical data are presented for eight of the 51 species. A checklist of the 43 other species is given; data on these are available from NRRC.Lapsana communis yielded the most oil (6.1%; dry, ash-free, plant sample basis).Ilex montana yielded the most polyphenol (21.5%) plus 4.5% oil.Agrimonia parviflora and Catalpa bignonioides gave substantial yields of polyphenol (20.0% and 17.9%, respectively), andPassiflora incarnata contained the most apparent protein (19.8%).Chrysopsis graminifolia, Solidago erecta, andVerbesina alternifolia were identified as rubber-producing species with 0.4-0.7% hydrocarbon.     

Selection and Characterization of Microorganisms Utilizing Thaxtomin A, a Phytotoxin Produced by Streptomyces scabies

Thaxtomin A is the main phytotoxin produced by Streptomyces scabies, a causal agent of potato scab. Thaxtomin A is a yellow compound composed of 4-nitroindol-3-yl-containing 2,5-dioxopiperazine. A collection of nonpathogenic streptomycetes isolated from potato tubers and microorganisms recovered from a thaxtomin A solution were examined for the ability to grow in the presence of thaxtomin A as a sole carbon or nitrogen source. Three bacterial isolates and two fungal isolates grew in thaxtomin A-containing media. Growth of these organisms resulted in decreases in the optical densities at 400 nm of culture supernatants and in 10% reductions in the thaxtomin A concentration. The fungal isolates were identified as a Penicillium sp. isolate and a Trichoderma sp. isolate. One bacterial isolate was associated with the species Ralstonia pickettii, and the two other bacterial isolates were identified as Streptomyces sp. strains. The sequences of the 16S rRNA genes were determined in order to compare thaxtomin A-utilizing actinomycetes to the pathogenic organism S. scabies and other Streptomyces species. The nucleotide sequences of the γ variable regions of the 16S ribosomal DNA of both thaxtomin A-utilizing actinomycetes were identical to the sequence of Streptomyces mirabilis ATCC 27447. When inoculated onto potato tubers, the three thaxtomin A-utilizing bacteria protected growing plants against common scab, but the fungal isolates did not have any protective effect.     

Geographical and seasonal patterns of epiphytic diatoms on a subtropical mangrove (Kandelia candel) in southern China

Geographical and seasonal patterns of epiphytic diatoms on a subtropical mangrove (Kandelia candel (L.) Druce) were examined at four sites in southern China. A total of one hundred and three epiphytic diatom species and varieties belonging to 40 genera were identified. Dominant species included Nitzschia fasciculata, Luticola mutica and Achnanthes javanica var. subcontricta. Further analysis using canonical correspondence analysis revealed three diatom associations which could be closely related to environmental variables such as salinity and nutrients resources of nitrogen and phosphate. Epiphytic diatom assemblages on roots would be a good indicator for the evaluation of water quality in mangroves.     

Variation within flax (Linum usitatissimum) and barley (Hordeum vulgare) in response to allelopathic chemicals

Summary A possible method of manipulating allelopathy would be to develop crop varieties showing an increased tolerance to allelopathic chemicals. We therefore examined four flax (Linum usitatissimum) varieties and two wild Linum species in the presence of p-coumaric acid and four barley (Hordeum vulgare) varieties in the presence of p-coumaric acid, scopoletin and wild oat (Avena fatua) extract. Analysis of variance indicates significant interaction between variety and treatment for shoot and root growth for seedling flax, shoot growth for older flax, and root growth for seedling barley. These differences in tolerance between varieties could be exploited to develop-varieties with greater tolerances to the allelochemicals produced by weeds or in crop residues and therefore potentially more tolerant of the presence of weeds.     

Photosynthetic efficiency and survival of Dactylis glomerata and Lolium perenne following low temperature stress

Resistance to low temperature is crucial for overwintering crops. In this work we compared the resistance to low temperature treatment of some varieties of two forage grass species Dactylis glomerata L. and Lolium perenne L. in order to elucidate the reason for the better resistance found in some species. The variety Amila of D. glomerata and Diament of L. perenne were more tolerant to low temperature stress during the emergence and tillering phases as compared to the varieties Amera and Gagat. The improved tolerance and ability for recovery after stress were associated with the better recovery of photosynthetic efficiency of these varieties and better survival of their shoots after low temperature stress.     

Anchored simple-sequence repeats as primers to generate species-specific DNA markers in Lolium and Festuca grasses

Simple-sequence repeats (SSRs) comprising three tetranucleotide repeat sequences with two-base ’anchors’, namely 5′-(AGAC)₄GC, 5′-AC(GACA)₄ and 5′-(GACA)₄GT, were used in PCR reactions as primers to develop inter-SSR DNA fingerprints of the outbreeding grass species Lolium multiflorum, L. perenne, Festuca pratensis and F. arundinacea. Each species was represented by DNA samples from 3 to 6 varieties. In all four species distinctive species-specific DNA profiles were produced that were common across a number of varieties despite their diverse origin. While the fingerprints of the two ryegrasses, L. multiflorum and L. perenne, were the most similar, a number of inter-SSR DNA markers were generated that enabled them to be distinguished from each other. Some slight variations were found between varieties, which provided putative variety-specific markers for cultivar identification. In addition, variations in the DNA profiles of the genotypes of L. multiflorum and F. pratensis were examined, and the results showed that variety-specific fingerprints are integrated patterns made up from the profiles of individual genotypes. Amongst the primers used, AC(GACA)₄ generated the best distinction between Lolium and Festuca individuals and provides an effective new tool for genome identification. A number of species-discriminating sequences, ranging in size between 550 bp and 1,600 bp, were cloned: three clones for F. pratensis, one clone for L. multiflorum and one clone for F. arundinacea. A F. pratensis fragment pFp 78H582 was sequenced. Southern hybridization confirmed the presence of this fragment in F. arundinacea (which contains one genome of F. pratensis), but no homology was found with L. multiflorum. However, a F. arundinacea clone amplified with (GACA)₄GT, pFa 104H1350, was found to be unique to the F. arundinacea genome. Received: 23 June 1999 / Accepted: 27 August 1999     

Relation of CO(2) Compensation Concentration to Apparent Photosynthesis in Maize

Significant differences in CO₂ compensation concentration measured in the field among varieties of the species Zea mays L. are reported for the first time. CO₂ compensation concentrations were significantly (P≤ 0.01) and negatively correlated with apparent photosynthesis at 300 μl CO₂/liter air. The Michaelis constant (as defined) for a leaf was significantly (P≤ 0.01) and positively correlated with apparent photosynthesis among varieties. While the first correlation is similar to behavior of CO₂ compensation among species of different photosynthetic efficiency, the latter correlation is the converse of the behavior of Km among species.     

Consequences of Seed Origin and Biological Invasion for Early Establishment in Restoration of a North American Grass Species

Local, wild-collected seeds of native plants are recommended for use in ecological restoration to maintain patterns of adaptive variation. However, some environments are so drastically altered by exotic, invasive weeds that original environmental conditions may no longer exist. Under these circumstances, cultivated varieties selected for improved germination and vigor may have a competitive advantage at highly disturbed sites. This study investigated differences in early establishment and seedling performance between wild and cultivated seed sources of the native grass, Poa secunda, both with and without competition from the invasive exotic grass, Bromus tectorum. We measured seedling survival and above-ground biomass at two experimental sites in western Montana, and found that the source of seeds selected for restoration can influence establishment at the restoration site. Cultivars had an overall advantage when compared with local genotypes, supporting evidence of greater vigor among cultivated varieties of native species. This advantage, however, declined rapidly in the presence of B. tectorum and most accessions were not significantly different for growth and survival in competition plots. Only one cultivar had a consistent advantage despite a strong decline in its performance when competing with invasive plants. As a result, cultivated varieties did not meet expectations for greater establishment and persistence relative to local genotypes in the presence of invasive, exotic species. We recommend the use of representative local or regional wild seed sources in restoration to minimize commercial selection, and a mix of individual accessions (wild, or cultivated when necessary) in highly invaded settings to capture vigorous genotypes and increase the odds native plants will establish at restoration sites.