喀斯特天坑内孔雀藓属蒴齿亚显微结构研究

喀斯特天坑微环境对植物结构特征有显著的影响。采用扫描电子显微镜，探究孔雀藓属蒴齿在喀斯特天坑内的亚显微结构，旨在为微环境下藓类植物蒴齿结构特征研究提供参考。研究结果表明：①基于蒴齿的亚显微形态研究，孔雀藓属两个种，即黄边孔雀藓（Hypopterygium flavo-limbatum C.Muell）、东亚孔雀藓（Hypopterygium japonicum Mitt）蒴齿双齿层，内外齿层数均为16枚，外齿层背面均具"Z"字形的中脊，齿片形态、曲向、外齿层背侧脊纹、齿条腹侧横纹以及是否具节瘤具有明显的差异，属于稳定性特征，可作为系统分类的依据；而齿片长度、宽度、节片数、横脊数、中脊数，属于可变性特征，受环境因子的影响，在运用藓类植物蒴齿作为系统分类依据时应作性状的筛选。②光照度、空气温度、空气湿度以及海拔是影响天坑内黄边孔雀藓（H.flavo-limbatum）蒴齿形态结构发育生长的主要环境因子，空气湿度、光照度以及人为干扰度是影响天坑内东亚孔雀藓（H.japonicum）蒴齿形态结构发育生长的主要环境因子。两种孔雀藓属植物蒴齿结构受湿度的影响最大，其生境多为湿度大、土壤含水量丰富的环境。     

帕米尔木灵藓和细齿木灵藓（木灵藓科）的形态特征及其在中国的新分布

该文报道了采自新疆的木灵藓属中国2个新记录种——帕米尔木灵藓(Orthotrichum pamiricum)和细齿木灵藓(O.scanicum)。帕米尔木灵藓的识别特征为:叶尖钝,气孔隐型,多着生于孢蒴下部,外齿层齿片8对,干燥时蒴齿背曲,内齿层蒴条16,上部内曲;细齿木灵藓的识别特征为:叶尖部具细齿,气孔半隐型,蒴帽具分散的透明毛,内齿层和外齿层均16片,具8条黄色细沟,干燥时中部以上具沟。对这2种藓类的形态特征、生境和地理分布及与其相似种的形态学进行了比较分析,并绘制了每种的形态结构墨线图。木灵藓属植物在中国的新分布记录进一步表明,新疆地区富含生物多样性,并与中亚植物区系存在密切关系。     

苔藓植物孢子形态的研究(一)——几种泥炭藓(Sphagnum)孢子的光学研究和电子显微镜观察

泥炭藓(Sphagnum)是水湿或沼泽地区丛生藓类。其植物体形态和构造分化简单,孢子体仅具由配子体组织发育的假蒴柄;孢蒴球形,盖裂,无蒴轴及蒴齿分化,因而为鲜纲中一个独立的亚纲,在苔藓系统排列中,列为原始的类型之一。     

贵州喀斯特高原金发藓原变种(Polytrichum commune Hedw.var.commune)蒴齿水湿运动研究

为探究线齿藓类植物在水湿运动中蒴齿结构的变化及对孢子散发的影响,选取贵州喀斯特高原金发藓原变种(Polytrichum commune Hedw.var.commune)为研究对象,通过观察湿度变化下蒴齿结构差异及孢子释放规律,拟揭示水湿运动对孢子释放的影响和功能。结果显示:①湿度增加引起蒴齿间距及盖膜面积的显著增大,并在干燥时恢复。其中齿间距从8.33μm显著增加到11.53μm,同时盖膜面积扩大20%。②在连续风吹试验中,水湿运动初期孢子释放量显著提高,随蒴齿结构的恢复呈下降趋势,并最终保持在极低的孢子释放数量。同时发现,湿度增加导致孢子释放中簇孢占比的提高,并随孢子释放量的减少呈上升趋势,并在蒴齿结构恢复时达到显著差异。③通过单独对干燥期、水湿运动初期及蒴齿结构恢复期进行风吹试验发现,水湿运动初期孢子释放量显著高于干燥期和蒴齿结构再恢复期。当蒴齿结构恢复时,由于簇孢占比的提高,孢子的释放数量仍能显著高于干燥期。本研究表明在水湿运动中金发藓原变种蒴齿结构发生改变,进而显著提高孢子的释放量,并在蒴齿结构恢复时仍能保持高于干燥时的孢子释放能力,这对该物种的传播及繁衍具有积极的意义。     

基于形态学特征和分子数据的中国缺齿藓科初步研究

为探讨缺齿藓类与真藓科、提灯藓科的系统关系,理清缺齿藓科的系统位置和中国缺齿藓科分类问题,该研究以中国分布的缺齿藓科植物和相关类群4 000余份标本为材料,进行详细的形态学研究,并选用其中35种、40份样品的4个DNA片段(rps4、trnG、trnL-trnF、atpB-rbcL)联合数据用于分子系统分析,采用邻接法(NJ)和最大似然法(ML)构建分子树。结果表明:(1)在分子树中,缺齿藓类与真藓科植物分别聚在具有高支持率的不同分支上,叶形、叶细胞等形态学特征也有较大差异,缺齿藓类应从广义的真藓科分出。(2)在分子树中,虽然缺齿藓类与提灯藓科植物聚在同一分支中,但无形态学的共源性状,二者不应视为一个单系类群。(3)缺齿藓科是一个自然类群,缺齿藓科内属间存在着密切的系统关系,缺齿藓科的主要识别特征为:植物体小型,茎常分枝;叶形和叶细胞为丝瓜藓型(Pohlia-like),披针形至长椭圆形,中上部细胞狭长,线状菱形或蠕虫形;生殖苞多生于新生枝顶;蒴齿为互生双齿层,常有不同程度的退化或一层蒴齿缺失,稀双层蒴齿缺失。(4)中国缺齿藓科包含有5属,即缺齿藓属(Mielichhoferia)、丝瓜藓属(Pohlia)、拟丝瓜藓属(Pseudopohlia)、合齿藓属(Synthetodontium)和小叶藓属(Epipterygium),目前为止共计34种(含种下分类单位)。     

真藓属（Bryum Hedw.）蒴齿形态特征及其分类学意义

通过光学显微镜和扫描电子显微镜观察了中国产真藓属（Bryum Hedw.）12种植物蒴齿的形态特征。结果显示,根据真藓属齿片的曲向可以分为近直立、齿片伸入齿条间和齿片向外反曲等3种类型。根据齿毛的有无,也可分为3个类群。同时利用STATISTICA 6.0统计软件对12种真藓属植物进行聚类分析及主成分分析。研究结果显示,齿片的曲向类型、齿毛是否发育等形态特征可作为真藓属植物种间的分类依据,为藓类植物蒴齿形态特征与分类和系统进化关系的研究提供了新的资料。     

苔藓植物适应孢子传播的结构

本文论述了苔藓植物的真蒴柄、假蒴柄、生殖托柄、孢蒴、孢蒴表皮、蒴齿和弹丝等适应孢子传播的形态、结构和功能。     

苔癣植物适应孢子传播的结构

本文论述了苔癣植物的真蒴柄、假蒴柄、生殖托柄、孢蒴表皮、蒴齿和弹丝等适应孢子传播的形态、结构和功能。     

角苔孢蒴发育的显微观察

对角苔科(Anthocerotaceae)角苔(Anthoceros punctatus)孢蒴的形态和发育进行显微观察。通过观察发现,角苔孢蒴在开裂带处有2列特殊的表皮细胞分布,开裂带下方的细胞扁小且排列紧密,蒴壁最内层细胞在孢蒴发育后期其内切向壁和径向壁强烈加厚,弹丝细胞具明显加厚的壁,角苔孢蒴的上述结构特征都有利于孢子的散发。同时,在角苔孢子体上观察到了与苔类和藓类不同的独特特征。     

四种藓类植物叶片解剖结构观察

使用石蜡切片法对四川壤塘的 4种藓类植物叶片的结构进行解剖学观察和比较分析 ,结果表明扭口红叶藓Bryoerythrophylluminaequalifolium (Tayl.)Zand .、台湾拟金发藓Polytrichas trumformosum (Hedw .)G .Sm .和梨蒴珠藓BartramiapomiformisHedw .的中肋由多层细胞构成 ,并有明显的细胞分化 ,而长蒴紫萼藓GrimmiamacrothecaMitt.的中肋结构较简单 ,无明显的细胞分化。 4种藓类植物的叶片细胞都只有 1层 ,但台湾拟金发藓的叶片上有栉片 ,扭口红叶藓叶片细胞表面有细疣 ,长蒴紫萼藓的叶片细胞壁明显加厚。此外 ,4种植物的叶片厚度和中肋厚度 ,及其细胞密度之间差异都比较明显     

Invasive moss alters patterns in life-history traits and functional diversity of spiders and carabids

Invasive plants can modify terrestrial habitats and affect the natural faunal composition. In acidic coastal dunes the invasive moss Campylopus introflexus can form dense carpets that largely replace native vegetation. As shown in a previous study, moss invasion affects habitat structure and ground-dwelling arthropod diversity. We suggested that including the functional diversity concept in the analysis of moss invasion impacts may offer further insights. We used pitfall trap data to compare trait composition and functional diversity of spiders and carabids in (a) invaded, moss-rich (C. introflexus) and (b) native, lichen-rich (Cladonia spp.) acidic coastal dunes. Moss invasion induced shifts in the trait values body size and feeding preference (carabids) and hunting mode (spiders): Species were smaller in native sites, and the percentages of web-building spiders and phytophagous beetles were reduced in invaded sites. Furthermore, moss invasion led to a more heterogeneous trait composition for spiders, and changed functional diversity of both arthropod groups, although with the opposite effects: While spiders were functionally more diverse in invaded sites, moss invasion reduced carabid beetles’ functional diversity. We also observed changes in the relationship between species richness and functional diversity that indicate a high functional similarity for spiders but a lower one for carabid beetles in native grey dunes. C. introflexus invasion not only alters the arthropod diversity and assemblage structure of endangered acidic coastal dunes but also interferes at a functional level. These results provide further insight into the way plant invasions might alter the structure and function of ecosystems.     

Organellar genomes of the four-toothed moss,Tetraphis pellucida

Background

Mosses are the largest of the three extant clades of gametophyte-dominant land plants and remain poorly studied using comparative genomic methods. Major monophyletic moss lineages are characterised by different types of a spore dehiscence apparatus called the peristome, and the most important unsolved problem in higher-level moss systematics is the branching order of these peristomate clades. Organellar genome sequencing offers the potential to resolve this issue through the provision of both genomic structural characters and a greatly increased quantity of nucleotide substitution characters, as well as to elucidate organellar evolution in mosses. We publish and describe the chloroplast and mitochondrial genomes of Tetraphis pellucida, representative of the most phylogenetically intractable and morphologically isolated peristomate lineage.

Results

Assembly of reads from Illumina SBS and Pacific Biosciences RS sequencing reveals that the Tetraphis chloroplast genome comprises 127,489 bp and the mitochondrial genome 107,730 bp. Although genomic structures are similar to those of the small number of other known moss organellar genomes, the chloroplast lacks the petN gene (in common with Tortula ruralis) and the mitochondrion has only a non-functional pseudogenised remnant of nad7 (uniquely amongst known moss chondromes).

Conclusions

Structural genomic features exist with the potential to be informative for phylogenetic relationships amongst the peristomate moss lineages, and thus organellar genome sequences are urgently required for exemplars from other clades. The unique genomic and morphological features of Tetraphis confirm its importance for resolving one of the major questions in land plant phylogeny and for understanding the evolution of the peristome, a likely key innovation underlying the diversity of mosses. The functional loss of nad7 from the chondrome is now shown to have occurred independently in all three bryophyte clades as well as in the early-diverging tracheophyte Huperzia squarrosa.     

Monograph of the moss genus Macrodictyum (Broth.) E.H.Hegew. (Dicranaceae)

Abstract

Macrodictyum is a small acrocarpous moss genus of three species (M. latifolium (E.B.Bartram) M.J.Price, M. proliferum (Mitt.) E.H.Hegew., M. wrightii (Sull.) E.H.Hegew.). It grows in tufts and mats on trees or rocks at 450–1500 m in the Neotropics. The genus has a restricted distribution within the Neotropics and is currently known from only a few localities in Cuba, the Dominican Republic, and southeastern Brazil. Macrodictyum is characterized by four main features: 1) appressed, non-crispate, ovate–oblong, lingulate to ligulate or linear leaves; 2) large, rhomboidal, thin-walled cells in the upper leaf; 3) large, irregular, multicellular apical teeth; and 4) guide cells that are ventral at and above mid-leaf. These features are atypical of the Dicranaceae. However, Macrodictyum shares pseudautoicous sexuality, sheathing perichaetial leaves, and peristome structure with the large pantropical Dicranaceous genus Holomitrium Brid. In these two genera the peristome consists of 16 single, triangular, entire or weakly divided, fenestrate, striate teeth that are papillose throughout on both the inner and outer surfaces. Macrodictyum is retained in the Dicranoideae (Dicranaceae), close to Holomitrium, based on its pseudautoicous sexuality, sheathing perichaetial leaves, and peristome structure.     

A study in the light and electron microscope of the extruded peristome and related structures of the rumen ciliate entodinium caudatum

A study in the light and electron microscope of sections of the rumen ciliate Entodinium caudatum was undertaken in an attempt to elucidate the structure of the peristome when in the extruded state The conformation of the ciliary band on the peristome and the structure of the lining of the buccal cavity are described. The structure and position of a tuft of specialized sheet like extensions of the cell surface is also described.     

Higher taxa vs. functional guilds vs. trophic groups as indicators of soil nematode diversity and community structure

Biodiversity surrogates are often used in ecology to save money and time. One such widely used surrogacy method is the higher taxon approach, also known in the literature as taxonomic sufficiency. This approach has rarely been applied to microscopic organisms like soil microfauna, although there is a lack of detailed taxonomic knowledge regarding the latter. We tested taxonomic sufficiency for genus alpha and beta diversity, as well as for community structure of soil nematodes. We also tested whether the functional classifications of nematodes into functional guilds and trophic groups can serve as efficient indicators of nematode diversity and community structure. We used data from soil nematode communities from five different microhabitats (soil, soil moss, rock moss, low tree trunk moss and high tree trunk moss) in forested and non forested areas at five different stations (differing in elevation and aspect). Our results showed that both the higher taxon approach and the functional surrogacy approach could serve as reliable indicators of alpha and beta diversity. Furthermore, our community analysis of both taxonomic and functional composition identified that the variability at the finer scales, and namely the habitat structure, played the leading role in shaping nematode communities.     

秦岭石生苔藓结皮的微生物群落组成和多样性特征北大核心CSCD

苔藓结皮是地表重要的活性覆盖物,具有改善土壤性状、固土持水、固碳固氮等多种生态功能,微生物群落是苔藓结皮发挥生态功能的主要成分。为了探究湿润区石生苔藓结皮的微生物群落组成及其多样性特征,揭示其发育形成机制以及功能机理,该研究以秦岭北麓的泥峪、车峪、骆峪5个样地的石生苔藓结皮为研究对象,利用高通量测序技术,分析了石生苔藓结皮层的微生物群落组成、丰度、多样性,并测定分析养分与微生物群落的关系,为裸露岩石创面的生态修复提供理论依据。结果表明:(1)秦岭石生苔藓结皮层的全氮和有机质含量在4.16~8.26 g/kg、89.44~131.05 g/kg之间,且样点间均差异显著;全磷和全钾含量较低,分别为0.88~1.21 g/kg和13.50~18.10 g/kg。(2)秦岭石生苔藓结皮层中细菌占微生物群落组成的80%以上,且细菌的多样性也远高于真菌;其中细菌优势菌群为变形菌门(Proteobateria)、拟杆菌门(Bateroidetes)、放线菌门(Actinobacteria)和酸杆菌门(Acidobacteria),真菌优势菌群为子囊菌门(Ascomycota)和被孢霉菌门(Mortierellomycota)。(3)冗余分析(RDA)显示,全钾和有机质对优势细菌群落结构影响显著,变形菌和拟杆菌适宜生活在湿度大、营养状况良好的基质中;全磷和有机质对优势真菌群落结构影响显著,被孢霉菌门在低磷基质中更具生长优势。研究发现,细菌是秦岭石生苔藓结皮层的优势菌群,与旱区土生状况相比,秦岭石生苔藓结皮层的放线菌和酸杆菌的含量有所下降,而拟杆菌含量显著增加;对于真菌而言,子囊菌门和担子菌门的相对丰度明显减少,被孢菌门丰度显著增加;有机质是影响结皮层微生物群落组成最主要的养分因子,丰富的养分使湿润区石生苔藓结皮层的微生物群落结构更加复杂多样、物种组成更加丰富。     

Harmless nectar source or deadly trap: Nepenthes pitchers are activated by rain, condensation and nectar

The leaves of Nepenthes pitcher plants are specialized pitfall traps which capture and digest arthropod prey. In many species, insects become trapped by 'aquaplaning' on the wet pitcher rim (peristome). Here we investigate the ecological implications of this capture mechanism in Nepenthes rafflesiana var. typica. We combine meteorological data and continuous field measurements of peristome wetness using electrical conductance with experimental assessments of the pitchers' capture efficiency. Our results demonstrate that pitchers can be highly effective traps with capture rates as high as 80% but completely ineffective at other times. These dramatic changes are due to the wetting condition of the peristome. Variation of peristome wetness and capture efficiency was perfectly synchronous, and caused by rain, condensation and nectar secreted from peristome nectaries. The presence of nectar on the peristome increased surface wetness mainly indirectly by its hygroscopic properties. Experiments confirmed that pitchers with removed peristome nectaries remained generally drier and captured prey less efficiently than untreated controls. This role of nectar in prey capture represents a novel function of plant nectar. We propose that the intermittent and unpredictable activation of Nepenthes pitcher traps facilitates ant recruitment and constitutes a strategy to maximize prey capture.     

Structure,function, and development of the peristome of the moss,Rhacopilum tomentosum,with special reference to the problem of microfibril orientation by microtubules

Summary The movement of the outer peristome teeth of the sporangium of the moss,Rhacopilum tomentosum, is driven by different swelling velocities of the outer (plates) and inner (ridges) wall thickenings due to suberin-like substances and wax-lamellae which enclose the ridges. The plates do not contain suberin-like material. The hydrophobic materials are secreted with the participation of smooth tubular ER.—When the local wall thickenings of the peristome teeth are formed, microtubules are concentrated along the plasmalemma in the thickening regions. They run along the crest of the developing plates (i.e., normal to the long axis of the tooth) and parallel to the long axis in the ridge cells. The wall thickenings are composed of layers of parallel microfibrils and of matrix substances. With a few exceptions microtubules and microfibrils have different directions. Golgi vesicles, subsurface ER and coated regions in the plasmalemma also are involved in cell wall formation. The function of the microtubules is discussed.