葫芦藓（Funaria hygrometrica）配子体和孢子体重金属富集特性比较

通过对湘西茶田钒矿废弃冶炼厂矿渣上葫芦藓的野外生态调查和采集,利用原子吸收光谱仪、电感耦合等离子发射光谱仪和原子荧光光谱仪分析了葫芦藓配子体和孢子体及其基质重金属含量。结果表明葫芦藓配子体和孢子体富集了大量的重金属,各重金属元素在配子体和孢子体间的富集存在较大的差异,配子体比孢子体显著富集重金属元素（p<0.05）,Zn和Mn在葫芦藓植物体中比其他重金属元素更高。同时也讨论了重金属在苔藓植物中的富集及生物阻抗的作用。     

Gametophyte contribution to sporophyte growth on the basis of carbon gain in the fern <Emphasis Type="Italic">Thelypteris palustris</Emphasis>: effect of gametophyte organic-matter production on sporophytes

At an early stage of growth gametophytes support the sporophytes of ferns. Young sporophytes become independent of gametophytes when the first leaves develop. Although large fern gametophytes produce multiple archegonia simultaneously, only one sporophyte is typically established on one gametophyte. The number of sporophytes is believed to be controlled in two possible directions, from gametophyte to sporophyte or from preceding sporophyte to another sporophyte. To investigate the effects of gametophytes on their sporophytes, we studied the relationship between organic matter production by gametophytes and the growth of young sporophytes of Thelypteris palustris. We cut gametophytes in half (CGs) to reduce the gametophytes’ production of matter. There was no significant difference between the growth of sporophytes on intact gametophytes (IGs) and that on CGs. According to our estimates, based on the rate of organic matter production, the large gametophyte was able to produce two or more sporophytes. The resources required for CGs to make similar-sized sporophytes was twice that for IGs. In polyembryony each of the multiple sporophytes was similar in size to the single sporophytes. Resource limitation does not seem to explain why fern gametophytes establish single sporophytes.     

除草剂苄嘧磺隆对粗梗水蕨配子体生长和性器官分化的影响

 稻田施用的除草剂可能会污染邻近水域,对非靶标水生植物产生影响。国家二级重点保护野生植物粗梗水蕨(Ceratopteris pteridoides)主要分布于稻田及其周围水域,其有性繁殖敏感阶段与除草剂施用时间一致,配子体易暴露在除草剂污染中。为了评价除草剂污染对水生态环境特别是对非靶标国家重点保护野生水生植物的影响,保护生物多样性和水生生态环境,该文研究了除草剂苄嘧磺隆(Bensulfuron-methyl)对粗梗水蕨配子体生长和性器官分化的影响。结果表明,苄嘧磺隆对粗梗水蕨孢子萌发没有影响,但对其配子体生长有抑制作用。苄嘧磺隆浓度和粗梗水蕨配子体面积呈明显的剂量效应关系,苄嘧磺隆对粗梗水蕨配子体生长抑制的EC₅₀(半数效应浓度)为0.086μg&;#8226;L^-1,低于已报道的环境背景浓度。随着苄嘧磺隆浓度升高,粗梗水蕨的雌雄同体配子体逐渐减少,且配子体上颈卵器形成时间推迟。在苄嘧磺隆为10μg&;#8226;L^-1时,粗梗水蕨没有雌雄同体配子体形成。以上研究结果表明,低浓度苄嘧磺隆可抑制粗梗水蕨配子体的生长并影响其性器官的分化,使粗梗水蕨有性繁殖能力减弱。     

Distribution of Potassium, Calcium and Magnesium in the Gametophyte and Sporophyte Generations of Funaria hygrometrica Hedw

Analyses have been made of the K, Ca and Mg in separated sporophytes,spores and gametophytes of the moss Funaria hygrometrica duringsporophyte development. Degeneration of the gametophyte wasaccompanied by loss of K and a gain in Ca while the K contentof the developing sporophyte increased more rapidly than thatof Ca. The presence of an air–gap in the expanding capsulesignificantly influenced the observed cellular location of ions.Relative to the sporophyte the spores were shown to have a higherK and a lower Ca concentration. The behaviour of Mg was intermediatebetween K and Ca throughout. Funaria hygrometrica, potassium, calcium, magnesium, cation distribution, gametophyte, sporophyte     

A methodology for large-scale Athyrium sheareri gametophyte proliferation and sporophyte production using tissue culture

Tissue culture methods using gametophytes are considered the easiest ways to mass-produce fern sporophytes. The aim of this study was to develop a practical propagation method for the ornamental fern, Athyrium sheareri. The gametophytes obtained from in vitro spore germination were used as experimental materials. We used the chopping method to investigate the culturing conditions for proliferating gametophytes and the blending method for evaluating the mass production of sporophytes in mixed soil. Gametophyte proliferation was determined via Knop medium, various concentrations of Murashige and Skoog (MS) basal medium (1, 1/2, 1/4), and media components (sucrose, nitrogen source, and activated charcoal). The fresh weight of the gametophytes increased by more than 24-fold in 1/2 MS medium. In addition, 1 g of gametophyte could produce a maximum of 255.3 sporophytes in a mixed soil of 7.5 cm² area. Treating gametophytes with exogenous plant growth regulators promoted the formation and growth of sporophytes. The cultivated young sporophytes were acclimated and successfully grown in greenhouses. We developed a mass production protocol for A. sheareri sporophytes suitable for field application, which is expected to have commercial value.

     

Practical methodology for gametophyte proliferation and sporophyte production in green penny fern (Lemmaphyllum microphyllum C. Presl) using mechanical fragmentation

Propagation of gametophytes and sporophytes using mechanical fragmentation has been considered a suitable method for mass production of ferns. This study aimed to develop a practical propagation method for Lemmaphyllum microphyllum C. Presl, which is a fern of significant ornamental and medicinal value. Gametophytes were obtained through in vitro spore germination and used for propagation experiments. The gametophyte was mechanically fragmented using a scalpel into small fragments, which were then used to investigate gametophyte proliferation. In addition, the gametophyte was fragmented using a blender and then used to study sporophyte formation. Optimal proliferation conditions of the gametophyte were determined using Murashige and Skoog (MS) basal medium (double-, full-, half-, quarter-strength), Knop medium, and medium components (sucrose, nitrogen sources, activated charcoal), at various concentrations. The fresh weight of the gametophyte was 14-fold higher than that of gametophytes (300 mg) used as culture material, when cultured on double-strength MS. Moreover, 1 g of the gametophyte fragmented in 25 mL of distilled water formed more than 430 sporophytes in a soil mixture in an area of 7.5 cm². The sporophytes were successfully cultivated in the greenhouse after acclimation. A large-scale production method for L. microphyllum that can be easily implemented in a fern production farm is outlined.

     

Insight into the pattern of heavy-metal accumulation in lichen thalli

BackgroundHeavy metals that pass through the plasmalemma are expected to influence on lichen metabolic processes; however, lichens may tolerate high concentrations of metals by sequestrating them extracellularly. Heavy metal accumulation level fundamentally determine the success of lichens in the colonisation of polluted sites; however, the proportions between extra- and intracellular metal concentrations in lichen thalli are still poorly recognized. In this study metal accumulation patterns of selected toxic trace elements, i.e. Pb, Cd, and micronutrients, i.e. Zn, Cu and Ni, in Cladonia cariosa thalli were recognised in relation to extra- and intracellular fractions.MethodsThe intracellular and total concentrations of Zn, Pb, Cd, Cu and Ni in lichen thalli collected from eleven variously polluted sites were determined by means of atomic absorption spectrometry. Additionally, organic carbon and total nitrogen contents as well as pH of soil substrate were measured.ResultsThe accumulation patterns differed between studied metal elements; the major part of Zn, Pb and Cd loads was accumulated extracellularly, whereas Cu and Ni accumulation was mostly intracellular. Like toxic trace elements, Zn was accumulated mainly extracellularly at high polluted sites. The non-linear models most reliably reflect relationships between intracellular and extracellular metal contents in C. cariosa thalli. The intracellular contents of Zn, Pb, Cd and Cu increased slower at higher than at lower extracellular concentrations. Moreover, at higher total concentrations of elements in the thalli, their extracellular proportions were markedly increased.ConclusionThe results suggest that in the face of extreme Zn-enrichment, lichens demonstrate the ability to accumulate the excess of Zn outside the cells. Therefore, it can be concluded that metal accumulation depend not only on the element but also on its abundance in the environment and direct availability for lichens. The studied species showed a defence against excessive intracellular accumulation when a given element is in excess. Such capability may facilitate the colonization of extremely polluted sites by certain pioneer lichens.     

The evolution of root hairs and rhizoids

Background

Almost all land plants develop tip-growing filamentous cells at the interface between the plant and substrate (the soil). Root hairs form on the surface of roots of sporophytes (the multicellular diploid phase of the life cycle) in vascular plants. Rhizoids develop on the free-living gametophytes of vascular and non-vascular plants and on both gametophytes and sporophytes of the extinct rhyniophytes. Extant lycophytes (clubmosses and quillworts) and monilophytes (ferns and horsetails) develop both free-living gametophytes and free-living sporophytes. These gametophytes and sporophytes grow in close contact with the soil and develop rhizoids and root hairs, respectively.

Scope

Here we review the development and function of rhizoids and root hairs in extant groups of land plants. Root hairs are important for the uptake of nutrients with limited mobility in the soil such as phosphate. Rhizoids have a variety of functions including water transport and adhesion to surfaces in some mosses and liverworts.

Conclusions

A similar gene regulatory network controls the development of rhizoids in moss gametophytes and root hairs on the roots of vascular plant sporophytes. It is likely that this gene regulatory network first operated in the gametophyte of the earliest land plants. We propose that later it functioned in sporophytes as the diploid phase evolved a free-living habit and developed an interface with the soil. This transference of gene function from gametophyte to sporophyte could provide a mechanism that, at least in part, explains the increase in morphological diversity of sporophytes that occurred during the radiation of land plants in the Devonian Period.     

Regulation of a Sub-sexual Life Cycle in a Moss: Evidence for the Occurrence of a Factor for Apogamy in Physcomitrium

As demonstrated in our earlier studies, the differentiationof apogamous sporophytes on the secondary protonema of the mossPhyscomitrium pyriforme Brid. requires an exogenous supply ofsucrose in the medium. In the present work, similar differentiationwas observed in the leaf cells of aged gametophytes. The experimentsindicate an accumulation in the leaves of a sporophytic factorwhich initiates a de novo differentiation of sporophytes fromleaf cells without the intervention of sexual reproduction.In the absence of sucrose, the factor for apogamy was not present.Highlight intensity (5000–6000 lx) also inhibited itsproduction. There was no evidence that its presence interferedwith or inhibited production of gameto-phores. Growth regulatorssuch as IAA and kinetin altered only the effectiveness of thissporophytic factor, demonstrating that it was endogenous. Sporogenesisin the apogamous sporophytes took place without orthodox meiosis. Results obtained by using different exogenous environments forthe in vitro differentiation of callus into gametophytes orsporophytes are also reported. These support our contentionthat there is an accumulation of a sporophytic factor in thegametophytic callus cells, which is diluted during the processof differentiation. The morpho-regulatory influence of lightin the differentiation of apical cells with three cutting facesfrom unorganized callus is also considered.     

Zinc, Lead and Cadmium Tolerance, Uptake and Accumulation by the Common Reed,Phragmites australis(Cav.) Trin. ex Steudel

Zinc (Zn), lead (Pb) and cadmium (Cd) tolerance in populationsof seedlings ofPhragmites australisraised from seeds collectedfrom a mine site (Plombières, Belgium) contaminated withZn, Pb and Cd and three ‘clean’ sites (Felixstowe,UK; Wisbech, UK; and Mai Po, Hong Kong) were studied under glasshouseconditions. Small differences were found between the metal-contaminatedpopulation and the three ‘clean’ populations whenseedlings were grown in 1.0 µg  ml^-1Zn and 10.0 µgml^-1Pb treatment solutions. In general, however, different populationsof seedlings showed similar growth responses, metal uptake andindices of Zn, Pb and Cd tolerance when cultured in the samemetal-contaminated media for 89 d or in the same metal treatmentsolutions (ZnSO₄:1.0 and 4.0 µg ml^-1Zn; Pb(NO₃)₂: 10.0and 25.0 µg ml^-1Pb; CdSO₄: 0.5 and 1.0 µg ml^-1Cd)for 3 weeks. There was insufficient evidence to support thehypothesis that the metal-contaminated population has evolvedto a Zn-, Pb- or Cd-tolerant ecotype but the results indicatedsome differentiation between the populations with that fromHong Kong being the least productive under the experimentalconditions used. The implications of the findings on selectionof provenances for use in constructed wetlands for wastewatertreatment are discussed. Metal accumulation; heavy metal tolerance; Phragmites australis; population differentiation     

Plant regeneration of the arsenic hyperaccumulator <Emphasis Type="Italic">Pteris vittata</Emphasis> L<Emphasis Type="Italic">.</Emphasis> from spores and identification of its tolerance and accumulation of arsenic and copper

An in vitro plant regeneration system was established from the spores of Pteris vittata and identification of its tolerance, and accumulation of gametophytes and callous, to arsenic (As) and copper (Cu) was investigated. The highest frequency (100%) of callus formation was achieved from gametophyte explants treated with 0.5 mg l^?1 6-benzylaminopurine (6-BA) + 0.5 mg l^?1 gibberellin acid (GA). Furthermore, sporophytes were differentiated from the callus tissue derived from gametophyte explants on MS medium supplemented with 0.5 mg l^?1 6-BA, 0.5–1.0 mg l^?1 GA and additional 300 mg l^?1 lactalbumin hydrolysate (LH) for 4 weeks. The optimum combination of ½ MS + 1.0 mg l^?1 GA + 0.5 mg l^?1 6-BA + 300 mg l^?1 LH promoted sporophyte formation on 75 ± 10% of the callus. Every callus derived from gametophyte explants could achieve 3–4 sporophytes. The in vitro growth of gametophyte and callus was accelerated in the medium containing Na₃AsO₄ lower than 0.5 mM, but this growth was inhibited with 2 mM Na₃AsO₄. And with the increase of Na₃AsO₄ in the culture medium from 0 to 2 mM, the As accumulation in gametophytes and callus increased and achieved a level of 763.3 and 315.4 mg kg^?1, respectively. Gametophytes and calluses transplanted to culture medium, supplemented with different concentrations of CuSO₄, are similar to those in Na₃AsO₄, and the Cu accumulation in gametophytes could achieve 7,940 mg kg^?1 when gametophytes were subcultured in medium containing 3 mM CuSO₄. These results suggested that the high efficiency propagation system could be a useful and rapid means to identify other heavy metal tolerance and accumulation. Further, the regeneration ability of callus made it possible for genetic transformation of this fern.     

Characterization of Cu and Zn Resistant Nicotiana plumbaginifolia Suspension Cultures

The mechanisms of Cu and Zn resistance in cultured Nicotianaplumbaginifolia cells were investigated. When crude extractsof both the Cu and Zn resistant cells were passed through SephadexG-75 gel filtration columns, two metal containing peaks wereidentified. In each case the Cu or Zn was associated with ahigh molecular weight fraction (ca. 70,000) and a low molecularweight fraction (less than 3,000) with the majority being associatedwith the low molecular weight fraction. The low molecular weightfraction in particular increased upon exposure of the cellsto the metals. Both the Cu and Zn resistant cells accumulated higher levelsof citrate and malate than the wild type cells in the presenceof the metals. The addition of citrate or malate, but not fumarateor succinate to the culture medium prevented Cu or Zn toxicityto wild type cells. These results suggest that the N. plumbaginifoliacells selected as resistant to Cu or Zn are resistant, at leastin part, because of their ability to accumulate the chelators,citrate and malate, in the presence of the metals. ¹Present address: Plantech Research Institute, MCI ResearchCenter, 1000 Kamoshida-cho, Midoriku, Yokohama 227 Japan (Received June 30, 1986; Accepted December 1, 1986)     

Sporophyte formation in experimentally-induced unisexual female and bisexual gametophytes ofLygodium japonicum

Unisexual female and male and bisexual gametophytes were experimentally induced inLygodium japonicum. A single bisexual gametophyte was isolated in a dish and a female gametophyte was paired with a male one to allow intragametophytic selfing and intergametophytic mating, respectively. About 30% of the females formed sporophytes but no bisexual gametophytes formed them.     

GENETIC LOAD IN OSMUNDA REGALIS POPULATIONS

Osmunda regalis sporophytes form haploid spores which develop into functionally hermaphroditic gametophytes. The self-fertilization of such gametophytes results in zygotes which are completely homozygous. Spore samples collected from sporophytes in natural populations were used to establish gametophyte cultures. The majority of these gametophytes were unable to form viable embryos when only self-fertilization was possible. Controlled selfing and crossing experiments revealed that the inability of these homozygous embryos to develop normally is attributable to the presence of recessive lethals. To account for this genetic load, an hypothesis is proposed integrating the morphology and ecology of the gametophyte generation with the polyploid genetic system of the sporophyte generation.     

安徽大龙山国家森林公园东亚小金发藓配子体与孢子体个体性状及其相互关系

植物性状是植物对环境变化响应和适应的综合反映。目前对苔藓植物个体水平功能性状的研究较为匮乏。以安徽大龙山国家森林公园分布的东亚小金发藓（Pogonatum inflexum）雌株为例,在其孢子体成熟期测定地上部分孢子体和配子体的形态特征及生物量,系统分析了植株性状变异特征、异速生长关系及协变（整合）格局。结果表明,东亚小金发藓配子体形态性状变异性高于孢子体,且二者生物量变异系数最大。孢子体高度是配子体的2倍,但其生物量仅占地上部分的23%。孢子体和配子体功能性状之间有一定相关性;形态性状（Y）与生物量（X）之间多为指数<1.0异速生长关系,而孢子体和配子体生物量之间为等速生长关系（指数为1.135±0.158）。孢子体生物量分配比例随个体增大而显著减小,体现出显著的负的个体大小依赖。主成分分析表明,东亚小金发藓孢子体和配子体主要个体性状具有不同的协变方向（即两个不同的性状群）,其中孢子体生物量是两类性状群的关键结点。综合来看,东亚小金发藓个体性状间具有与维管植物相似的协变关系。     

NORTHERN AND SOUTHERN HEMISPHERE HYBRIDS OF MACROCYSTIS (PHAEOPHYCEAE)1

All combinations of individuals of Macrocystis pyrifera (L.) C. Agardh, M. integrifolia Bory, and M. angustifolia Bory hybridized. Gametophyte isolates obtained from 18 individuals were used, including M. pyrifera and M. integrifolia from the extremes of their Northern Hemisphere ranges along the Pacific Coast of North America and M. pyrifera and M. angustifolia from Tasmania, Australia. All combinations of gametophytes produced sporophytes of normal morphology, with the exception of crosses involving three gametophyte isolates. One female (M. integrifolia) and two male (M. pyrifera and M. angustifolia)gametophyte isolates were unable to produce normal sporophytes in combination with gametophytes of the opposite sex. Some cultures of female gametophytes produced abnormally shaped parthenogenetic sporophytes. Gametophytes and sporangia of M. pyrifera had n= 16 chromosomes. The M. integrifolia female gametophyte that was unable to produce normal sporophytes had n = ca. 32 chromosomes. These results show that these species of Macrocystis have not become reproductively isolated. Although these species may be considered conspecific according to the biological species concept, we recommend that they continue to be recognized as separate species based on morphological differences.     

Effects of temperature and nutrients on microscopic stages of the bull kelp (Nereocystis luetkeana,Phaeophyceae)

Warming ocean temperatures have been linked to kelp forest declines worldwide, and elevated temperatures can act synergistically with other local stressors to exacerbate kelp loss. The bull kelp Nereocystis luetkeana is the primary canopy-forming kelp species in the Salish Sea, where it is declining in areas with elevated summer water temperatures and low nutrient concentrations. To determine the interactive effects of these two stressors on microscopic stages of N. luetkeana, we cultured gametophytes and microscopic sporophytes from seven different Salish Sea populations across seven different temperatures (10–22°C) and two nitrogen concentrations. The thermal tolerance of microscopic gametophytes and sporophytes was similar across populations, and high temperatures were more stressful than low nitrogen levels. Additional nitrogen did not improve gametophyte or sporophyte survival at high temperatures. Gametophyte densities were highest between 10 and 16°C and declined sharply at 18°C, and temperatures of 20 and 22°C were lethal. The window for successful sporophyte production was narrower, peaking at 10–14°C. Across all populations, the warmest temperature at which sporophytes were produced was 16 or 18°C, but sporophyte densities were 78% lower at 16°C and 95% lower at 18°C compared to cooler temperatures. In the field, bottom temperatures revealed that the thermal limits of gametophyte growth (18°C) and sporophyte production (16–18°C) were reached during the summer at multiple sites. Prolonged exposure of bull kelp gametophytes to temperatures of 16°C and above could limit reproduction, and therefore recruitment, of adult kelp sporophytes.     

Effects of Dimethyl Sulphoxide on the Gametophytic and Sporophytic phases of Pteridium aquilinum (L.) Kuhn

Dimethyl sulphoxide (DMSO) at concentrations of up to 10 mlper litre of growth medium was found to have no significantinfluence upon Pteridium gametophyte growth or morphology However,significant effects upon embryo development and sporophyte morphologywere shown The most striking of these was that more than oneembryo developed from each fertilized gametophyte grown on DMSOmedium Two to five embryos regularly developed on each gametophytecultured on media containing this solvent, control gametophytesbore single sporophytes The significance of these findings inrelation to theories concerning polyembryony are discussed Pteridium, dimethyl sulphoxide, polyembryony     

Effect of temperature and photon fluence rate on gametophytes and young sporophytes of Laminaria ochroleuca Pylaie

We analysed the effects of temperature and photon fluence rate on meiospore germination, growth and fertility of gametophytes, and growth of young sporophytes of Laminaria ochroleuca. Maximum percentages of germination (91–98%) were obtained at 15°C and 18°C, independent of photon fluence rate. Optimal development of female gametophyte and maximum fecundity and reproductive success of gametophytes occurred at 15°C and 18°C and at 20 and 40 μmol m^–2 s^–1. Maximum relative growth rate of young sporophytes after 2 weeks of culture was achieved under the same conditions. L. ochroleuca gametophytes cannot reproduce and growth of its sporophytes is not competitive at temperatures close to 10°C. Received in revised form: 31 August 2001 Electronic Publication     

Comparative study of the bioaccumulation and elimination of trace metals (Cd,Pb, Zn,Mn and Fe) in the digestive gland,gills and muscle of bivalve Pinna nobilis during a field transplant experiment

The purpose of this study was to investigate the long-term bioaccumulation and elimination of Cd, Pb, Mn, Zn and Fe by Pinna nobilis tissues after their 90 day-transplantation period at Téboulba fishing harbor. During the transplantation period, the Cd, Pb, Mn, Zn and Fe concentrations in the different tissues of the mussels were measured before and after exposure period. Metal (Cd, Pb, Mn, Zn and Fe) accumulation in P. nobilis mussels varied depending on the analyzed tissue and the caging times. Notable differences in Cd, Pb, Mn, Zn and Fe accumulation patterns within the digestive gland, gills and muscle were found and may be due to the ability of each tissue to accumulate metals. During the depuration phase, the elimination of Cd, Pb, Mn, Zn and Fe depended on the target tissue and the metal speciation. Cd, Pb, Mn and Fe were eliminated rapidly from one organ and increased in other when compared to those of 90 day transplanted mussels. The increase of metal loads during the elimination phase is not clear and particularly what kind of processes is responsible for such response. However, it is reasonable to assume that metals increase is related to the existence of an accumulation/detoxification mechanism, which involves the transport of metals from an organ to another. The data obtained indicate that because of the significantly high quantities of Cd, Pb, Mn, Zn and Fe accumulated during the exposure phase, the transplanted mussels are suitable bioindicators for monitoring trace metals in marine ecosystem.