A survey of trace elements in pteridophytes

Concentration of 11 trace elements (Ca, Sc, Cr, Fe, Co, Zn, Rb, Cs, Ba, La, and Ce) in 96 pteridophytes (fern and fern ally species) was determined by instrumental neutron activation analysis to evaluate a concentration range for each element and also to find species characteristic in the uptake of trace elements. Asplenium trichomanes was found to accumulate Sc, Cr, and Co to the highest concentrations among 96 pteridophytes. The highest concentration of Ca and Zn was observed for Asplenium obscurum. The other Pteridophytes exhibited only one element whose concentration was the highest. A positive correlation was found between the concentrations of Fe and Sc, and also between the concentrations of Cr and Co. The remarkable accumulation of lanthanides (La and Ce) was observed mainly in diversifying genera (Polystichum and Dryopteris in Dryopteridaceae, Diplazium in Woodsiaceae, and Asplenium in Aspleniaceae).     

Genetic diversity and phylogeography in two diploid ferns,Asplenium fontanum subsp. fontanum and A. petrarchae subsp. bivalens,in the western Mediterranean

Asplenium fontanum subsp. fontanum and A. petrarchae subsp. bivalens are diploid rock ferns of limestone outcrops of the western Mediterranean region. Asplenium fontanum subsp. fontanum occurs from Valencia through northeastern Spain to the Alpes‐Maritimes and Swiss Jura. Asplenium petrarchae subsp. bivalens occurs only on Majorca, in Valencia and possibly in southern Spain. We analysed allozyme and chloroplast genetic marker diversity in 75 populations of A. fontanum subsp. fontanum and 12 populations of A. petrarchae subsp. bivalens sampled from across their respective ranges. The two species show similar levels of species and population genetic diversity to one another and to other diploid European Asplenium taxa. Both are predominantly outbreeding, as indicated by F_IS = 0.108 and 0.167 respectively. Substantial between‐population differentiation results largely from differentiation between regions. Isolation by distance operates over limited geographic ranges, up to 50 km. In A. fontanum subsp. fontanum, the major geographical differentiation between Valencia and the rest of the taxon range probably represents an ancient range fragmentation. A less pronounced differentiation divides populations in the SW from those in the NE of the range, with evidence for a biogeographic link between the eastern Pyrenees and southeastern France. High diversity in the Pyrenees may either represent ancient population differentiation, or a suture zone. In A. petrarchae subsp. bivalens, populations on Majorca exhibit a subset of the genetic diversity present in Valencia, although the two regions are strongly differentiated by differing allele frequencies. Dispersal from the mainland may have founded Majorcan populations, although a role for in situ island survival cannot be excluded.     

The composition of lipids and fatty acids determined at various stages of haploid and diploid generations in the fern Adiantum capillus-veneris

The composition of lipids and fatty acids was determined at various developmental stages of gametophytes and sporophytes in the fern Adiantum capillus-veneris L. When the lipid content was expressed per g fresh weight, triacylglycerol was a major reserve lipid in spores and remained the dominant lipid in the gametophytes up to the 15th day after germination, but it was a minor one in the pinnae of sporophytes. In contrast, triterpenoids were abundant in sporophytes but not detected in gametophytes. When the content of fatty acids was expressed in percentage of the total fatty acids, the content of arachidonic acid in phosphatidylcholine and linolenic acid in diacyglyceryltrimethylhomoserine and phosphatidylcholine was significantly higher in both pinnae and petioles of sporophtes than in gametophytes. Significant differences in fatty acid composition of phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol and triacylglycerol were also noted between gametophytes and pinnae of sporophytes. All these differences were attributed to the difference of generation rather than tissue differences or age.
The content of monogalactosyldiacylglycerol, hexadecatrienoic acid in monogalactosyldiacylglycerol, and 3- trans hexadecenoic acid in phosphatidylglycerol was higher in the pinnae of sporophytes than in gametophytes or in young leaves of sporophytes. Electron microscopy of the ultrastructure of chloroplasts indicated that the high content of these components was consistent with the development of chloroplasts in pinnae.     

Negative phototropism in young gametophytes of the fern Schizaea pusilla

Schizaea pusilla is a rare fern that occurs in acidic bogs and is one of the few fern species that maintains a filamentous gametophyte throughout its development. To expand our knowledge of the physiology of this fern, phototropic responses were examined in young gametophytes. In contrast to germ filaments of other fern species, apical protonemata of young gametophytes are negatively phototropic in continuous white, red and blue light at all fluence rates tested. The expression of phototropic curvature is not limited by time since apical protonemata are also negatively phototropic when they are given brief exposures of light and then placed in the dark. In other lower plant groups such as mosses and some algae, the direction of phototropic curvature can change depending on light quality and intensity, but in young gametophytes of Schizaea, negative phototropic curvature was observed in all conditions studied. Blue light is the most effective in promoting the negative phototropic response in Schizaea.     

The purification and properties of a thiaminase I enzyme from nardoo (Marsilea drummondii)

Fronds of the fern nardoo (Marsilea drummondii) contain a thiaminase I enzyme at very high levels of activity. Highest levels of enzyme activity were found in vigorously growing plant material. The thiaminase I has been purified to a final sp act value of 2.07 μkat/mg protein at 30° and pH 6.5. It was shown to have similar properties to thiaminase I enzymes purified from bracken fern, rock fern and freshwater mussels. These enzymes have MW values in the range 93 000–115 000, energies of activation of 14 000 cal mol, pH optima of 8–9 and are quite stable in the pH range 3 to 12 and to extended incubation at 55°. The temperature for 50 % denaturation is 60–65°. p-CMB, mersalyl acid and HgCl₂ (10^t-6 M) are potent inhibitors, but monoiodacetic acid (10^?4 M) has no effect. A wide range of heterocyclic bases, sulphydryl compounds, and amines, including the non-aromatic amines 6-aminohexanoic acid and ethanolamine, act as co-substrates in the thiaminase I reaction; however, their effectiveness is dependent on both their degrees of basicity and to some extent, their stereochemistry. When the co-substrate activity of a range of substituted anilines were compared, no correlation was found between the degree to which the base activates the reaction and the pK_b (or Hammett's sigma constant) of the base.     

Anthurium roots for micropropagation and Agrobacterium tumefaciens-mediated gene transfer

Growth of Blechnum spicant gametophytes was optimal in MS liquid medium, a 16-h photoperiod, and it was unaffected by variation of the pH between 4.7 and 8.7. Antheridia were observed during all developmental stages of the gametophyte: filamentous, spatulate or cordate and their formation was induced by compounds excreted into the culture medium by mature gametophytes. This antheridiogen activity was found in the fractions corresponding to free and apolar esters of gibberellins. IBA at 5 μM and 50 μM, and BA at 50 μM inhibited antheridiogen. Exogenous application of GA₃ allowed spore germination but strongly inhibited gametophyte development; the two dimensional state was not reached. This revised version was published online in June 2006 with corrections to the Cover Date.     

早白垩世单缝孢真蕨植物新材料及其分类归属

在原位繁殖器官研究的基础上,描述了产于辽宁铁法盆地早白垩世地层中的单缝孢真蕨植物化石：Ａｔｈｙｒｉｕｍ ａｓｙｍｍｅｔｒｉｃｕｍ ｍｅｎｇ、Ｄｒｙｏｐｔｅｒｉｔｅｓ ｇｒａｃｉｌｉｓ ｓｐ．ｎｏｖ．Ｄ．ｌｉａｏｎｉｎｇｅｎｓｉｓ ｓｐ．ｎｏｖ．和Ａｓｐｌｎｉｕｍ ｐｏｐｏｖｉｉ Ｓａｍｙｌｉｎａ,并讨论了其分类归属.     

Influence of tissue culture conditions on apogamy in Dryopteris affinis sp. affinis

The naturally-occurring apogamy of some ferns can be modified by culture conditions and growth regulators. Gametophytes of the apogamic fern Dryopteris affinis sp. affinis L., were cultured on Murashige and Skoog (MS) basal medium. Changes in concentration of MS medium components, sucrose, agar and different pH values were tested. The addition of benzyladenine (4.43 M) and naphthalene acetic acid (0.53 M) enhanced sporophyte proliferation on the gametophytes. After one month in culture, the gametophytes formed callus with a high morphogenic capacity. Culture of calli on medium without growth regulators yielded about 10,000 sporophytes per 1 g fresh weight of callus. This pattern of differentiation slowed with time to a point where only gametophyte regeneration was observed.Abbreviations BA benzyladenine - 2,4-d 2,4-dichlorophenoxyacetic acid - F.W. fresh weight - MS Murashige & Skoog medium - NAA 1-naphthalene acetic acid - SE standard error     

山西蕨类植物新资料

报道了山西省新记录的蕨类植物6种1变种,隶属6科、7属,它们是井栏边草、东方狗脊、贵阳铁角蕨、雅致针毛蕨、沼泽蕨、毛轴假蹄盖蕨和高大耳蕨.     

Estimation of chronological age for sporophyte maturation in three semi-evergreen ferns in Hokkaido

To elucidate the life cycle time schedule of semi-evergreen ferns at natural sites in Sapporo, the chronological age for sporophyte maturation was estimated from the increase in the number of veins (NV, number of midrib branches) from overwintered to newly expanded leaves. The measurements were conducted on populations ofPolystichum braunii, Polystichum tripteron andDryopteris crassirhizoma at altitudes of 50–650 m on Mt. Teine to compare the interspecific maturation age of sporophytes. The mean age for sporophyte maturation was estimated to be 7.6 yr forP. braunii, 16.5 yr forP. tripteron and 12.6 yr forD. crassirhizoma. The minimum ages (1% fertility rate) for sporophyte maturation ofP. braunii, P. tripteron andD. crassirhizoma were 5.8, 11.0 and 7.9 yr, respectively. The maturation age was shortest forP. braunii and longest forP. tripteron. The maturation age of a species thus seems to differ according to altitude and habitat, and that of the present three species seems to be influenced by the geographical location of the species distribution. Contribution No. 3315 from the Institute of Low Temperature Science, Hokkaido University.     

蕨类植物配子体发育与生理生态研究进展

蕨类植物配子体为单倍体,结构简单,独立于孢子体生活,在研究其对环境的响应以及揭示其机理上都具有独特的优势。该研究从我国和国际两个分支出发,梳理了近年来全球范围内相关的文献资料,透视了蕨类配子体的发育和生理生态前沿科学和研究动态。在发育部分以研究进展为主要内容,国内研究以传统植物蕨类植物的配子体形态和发育的观察为主,而国外学者更关注于新技术和新方法在传统学科中的运用,如X光透射技术和流式细胞术。生理生态部分分为光合与呼吸作用、土壤逆境的响应、气候变化的响应以及对化感物质的响应4个板块。在光合作用的研究中,发现蕨类配子体会在光强的变化下产生自我保护机制,碳水化合物和脂质是配子体能量代谢中的重要指标。在土壤逆境的响应研究中,对砷有超富集作用的蜈蚣草配子体和耐高盐的铁角蕨配子体是配子体研究中较为突出的材料。荷兰地区广泛存在的耳蕨属蕨类,哥斯达黎加热带雨林的20种蕨类植物及水生蕨类槐叶萍,成为了证明配子体成活率和温度之间重要关系的实验例证。在化感作用研究中,主要通过紫茎泽兰根、茎和叶水提液对扇蕨等4种蕨类配子体的作用,证明了入侵植物对于蕨类植物配子体生长发育具有危害作用。在美国佛罗里达的一类爬树蕨也发现了同样的入侵植物现象。此外,还对几个新兴技术在配子体研究的前景进行了展望,并对已有技术进行了描述。该研究以多个角度介绍了国内外配子体的研究进展,希望有助于促进我国学者对该领域的深入研究。     

New Materials of the Early Cretaceous Monolete Spore Ferns and Their Taxonomic Study

Based upon the characters of the fertile segments and the reproductive structures, four early Cretaceous monolete spore ferns: Athyrium asymmetricum (Meng) comb. nov. of Athyriaceae, Asplenium popovii Samylina of Aspleniaceae, Dryopterites gracilis sp. nov. and D. liaoningensis sp. nov. of Dryopteriaceae have been described from Xiaoming′anbei Formation, Tiefa Basin, Liaoning Province, China.     

竹叶蕨配子体发育的培养观察

首次在光学显微镜下观察竹叶蕨孢子及其萌发、丝状体发育、片状体和生长点的形成及分化、原叶体细胞形态、假根及性器的发育等方面所表现出的显微特征。初步讨论竹叶蕨科从鳞始蕨科中分立出来的合理性,以及原叶体边缘细胞的形态、叶绿体对光的敏感性、假根的形态和精子器的形成及分化的系统学意义。     

福建中中新世紫萁属(紫萁科)的一个新种

丰富的化石记录显示中生代和新生代紫萁属在北半球广泛分布.本文描述了发现于福建中中新世佛昙群的紫萁属一新种:漳浦紫萁(Osmunda zhangpuensis Z.X.Wang and B.N.Sun,sp.nov.).化石小羽片保存完好,呈线状披针形,边缘具齿,羽状脉序.在该属现生种中,当前化石种与现生种Osmunda...     

The effects of the aggressive species Pteridium caudatum on the vegetation of Socorro Island: Restoration challenges and opportunities

Humans’ impacts on natural environments have become pervasive, and natural regeneration is often hampered by extreme soil degradation. This situation is exacerbated in insular habitats where introductions of non-native grazing mammals have left behind completely barren areas. Once mammals are removed, aggressive native or non-native plant species can grow vigorously. This leads to the question of whether biodiversity can return through native succession, or if other actions are needed to prevent invading pioneer species from causing successional arrest. This occurs on the remote Socorro Island, in the UNESCO World-Heritage Revillagigedo Archipelago, Mexico. To understand whether native plants are establishing at sites invaded by Pteridium caudatum, we evaluated natural regeneration in sites with different Pteridium cover in two contrasting zones of the island (dry and mesic). We also calculated plant stress indicators (midday leaf water potential, chlorophyl content and maximum quantum yield) for two native species—Dodonea viscosa and Psidium socorrense—growing in open areas and under Pteridium. Our results showed that Pteridium is a significant barrier to seedling establishment. Thus, restoration actions such as seeding and/or plantings should focus on areas without Pteridium cover. Certain local species can be used to restore degraded areas: P. socorrese and Waltheria americana could be used in dry zones, while D. viscosa could be sown in either dry or mesic zones. For adult plants of the two dominant shrubs, Pteridium cover neither imposes or ameliorates stress. Our results suggest that the restoration of plant diversity in the vast Pteridium-invaded areas of Socorro Island will require management actions, including progressive physical removal of Pteridium cover to activate natural regeneration. Pteridium removal can be accelerated by nucleation, planting adults of native shrubs to generate shading. This strategy could be viable if restoration programs involve conservation institutions and government agencies, who currently have critical human and technological resources on the Island.     

贵州蕨类植物新记录

报道了贵州省新记录的4种蕨类植物,分属3科,4属,它们是上毛凤丫蕨（Coniogramme suprapilosa）、具腺凸轴蕨（Metathelypteris glangdulosa）、光滑方秆蕨（Glaphyropteridopsis glabrata）和混淆鳞毛蕨（Dryopteris commixta）。     

FLEXURAL STIFFNESS ALLOMETRIES OF ANGIOSPERM AND FERN PETIOLES AND RACHISES: EVIDENCE FOR BIOMECHANICAL CONVERGENCE

Evidence for convergence in biomechanical and anatomical features of leaves (elastic modulus E, second moment of area I, taper of petioles, the longitudinal distribution of petiolar and laminar weight, and volumes of tissues) is presented based on a survey of 22 species (distributed among dicots, monocots, and ferns). In general, regardless of taxonomic affinity, petioles were found to be mechanically constructed in one of two ways: Type I petioles—as cantilevered, end-loaded beams with relatively uniform flexural stiffness (EI) (simple and palmate leaves); and Type II petioles—as tapered cantilevered beams whose static loadings (biomass) and EI increase basipetally (pinnate leaves). In general, collenchyma and sclerenchyma were found to be peripherally located in transections through Type I and II petioles, respectively. Statistical analyses within each species and among species with either type of petiole indicated that EI ≈ k₁Lp^2.98 and EI ≈ k₂Lp^2.05 for Type I and II petioles, respectively, where k₁ and k₂ are dimensional constants and Lp is petiolar length. The data are interpreted to indicate that Type I and II petioles mechanically operate to deal with static loadings in two distinct ways, such that Type II petioles function in an analogous manner to branches supporting separate leaves (leaflets). The convergence in mechanical “designs” among taxonomically distinct lineages (angiosperms and ferns) is interpreted as evidence for selection on mechanical attributes of load supporting structures (petioles).