中华缩叶藓孢子萌发与原丝体发育特征研究

通过室内人工培养中华缩叶藓的孢子,在光学显微镜下详细观察了其孢子萌发、原丝体发育及配子体发生的全过程.结果表明:中华缩叶藓的孢子在壁内萌发,随后分裂产生块状原丝体;块状原丝体上可产生两种丝状体,一种是具疣的棒状原丝体,另一种是由长圆柱状细胞组成的轴丝体;配子体原始细胞只产生于块状原丝体上.根据中华缩叶藓的孢子萌发和原丝体发育特征,并参照Nishida对藓类植物孢子萌发类型的划分,确定中华缩叶藓的萌发孢子型应属于缩叶藓型(Ptychomitrium-type).     

五种藓类植物的孢子萌发与原丝体发育

本文对中华缩叶藓(Ptychomitrium sinense)、狭叶缩叶藓(P.linearifolium)、威氏缩叶藓(P.wilsonii)、葫芦藓(Funaria hygrometrica)和立碗藓(Physcomitrium sphaericum)5种国产藓类植物的孢子萌发和原丝体发育进行研究,结果表明不同藓类孢子萌发和原丝体发育类型不同,孢子萌发和原丝体发育方式与藓类植物的生态环境有关.     

Conserved function of Rho-related Rop/RAC GTPase signaling in regulation of cell polarity in Physcomitrella patens

Cell polarity is fundamentally important to growth and development in higher plants, from pollen tubes to root hairs. Basal land plants (mosses and ferns) also have cell polarity, developing protonemal apical cells that show polar tip growth. Flowering plants have a distinct group of Rho GTPases that regulate polarity in polarized cell growth. Rop/RAC signaling module components have been identified in non-flowering plants, but their roles remain unclear. To understand the importance and evolution of Rop/RAC signaling in polarity regulation in land plants, we examined the functions of PpRop and PpRopGEF in protonemal apical cells of the moss Physcomitrella patens. Inducible overexpression of PpRop2 or PpRopGEF3 caused depolarized growth of tip-growing apical cells. PpRop2 overexpression also caused aberrant cross wall formation. Fluorescent protein-tagged PpRop2 localized to the plasma membrane, including the cross wall membrane, and fluorescent-tagged PpRopGEF3 showed polarized localization to the tip region in apical cells. Thus, our results suggest common functions of PpRop and PpRopGEF in the tip-growing apical cells and the importance of a conserved Rop/RAC signaling module in the control of cell polarity in land plants.     

羽枝青藓和瘤柄匐灯藓对入侵植物种子萌发和幼苗生长的影响

入侵植物会通过化感作用等手段抑制本地种的生存繁衍,但本土植物尤其是地被层的藓类植物对入侵植物有何影响尚不清楚。本文以本土羽枝青藓和瘤柄匐灯藓为供体材料,以恶性入侵杂草稗草和野胡萝卜为受试材料,从藓丛结构特征和化感作用角度探究藓类植物对入侵植物种子萌发和幼苗生长的影响。结果表明: 2种入侵植物种子落入藓丛后其发芽率、发芽势和发芽指数均受到显著抑制,抑制效果为藓丛上部>藓丛下部>无藓丛。稗草种子落入藓丛下部会显著影响其根长和根芽比。施加藓类浸提液均显著降低2种入侵植物的发芽率、发芽势及发芽指数,但呈现不同的浓度效应。施加浸提液在一定程度上增加了稗草幼苗芽长、根长和根芽比,但对野胡萝卜无明显的规律性影响。藓类植物对2种入侵植物种子萌发和幼苗生长的化感综合效应均表现为抑制作用,其中,野胡萝卜的敏感性大于稗草,且高浓度下更加明显。可见,藓类植物对入侵植物种子萌发和幼苗生长具有一定抑制作用。     

Influence of metabolic stress on the inheritance of cell determination in the moss, Pottia intermedia

Epigenetically-determined apogamy in aposporous regenerants of the moss Pottia intermedia persists during vegetative propagation, the capacity of apogamy being inherited by individual aposporous protonemal cells. To test Bauer-Lazarenko's proposal that stable apogamy in mosses may be due to some self-replicating cytoplasmic factor, the effects of different metabolic stress treatments on the expression of apogamy have been tested. Chronic metabolic stress caused by long-term growth of autotrophic aposporous protonema on mineral medium with 0.25% of casamino acids and on Murashiga-Skoog (MS) medium with sucrose and phytohormones, as well as by transitory action of high kinetin concentration, have a much stronger influence on the expression of apogamy, than short-term stress treatments with RNase and Pb(2+). Apogamy has been found to be lost stably, after prolonged growth on MS medium containing kinetin and ABA. The proposal that the capacity for apogamy is related to the release of aposporous protonemal cells from a putative factor for apogamy is discussed.     

北京小龙门自然保护区四种苔藓鸟巢的观察

2004年8月20～22日在北京小龙门自然保护区,分别对宝兴歌鸫（Turdus mupinensis）、黄眉姬鹪（Ficedula narcissina）、白腹蓝鸫（Cyanoptila cyanomelana）和北红尾鸲（Phoenicurusauroreus）4种鸟的鸟巢的结构和巢材进行了观察,发现他们均用藓类植物作为巢材。经过鉴定,这些藓类植物共7种,分属于4科,其中最多是小牛舌藓（Anomodon minor）。该文还对巢材中藓类植物的分布、生物学特性和鸟类取材的行为等进行了初步分析。     

Two new species of Distichophyllum from Malaya

Abstract

The germination and establishment abilities of different types of propagules under natural conditions is an area in bryophyte reproductive biology that is largely unknown. In some species gametophyte fragments, rather than spores, may be primarily responsible for establishment of new colonies in nature, and the presence of other mosses may have an effect on establishment processes. These ideas were tested experimentally using four species of Tortula grown in a glasshouse under semi-natural conditions. The relative germination and growth abilities of spores and gametophytic fragments were tested under each combination of the following treatments: (1) continuous hydration (using a mist system), or periodic drying; (2) substrate of bare sand, a clump of Dicranum scoparium, or (for spores only) the clump of Tortula from which sporophytes were taken. Fragments produced new shoots much more quickly than spores under either hydration condition but spores germinated at a higher rate. Germination rates of both spores and fragments were greatly reduced (usually to zero) in clumps of Tortula or Dicranum under either hydration condition. Some differences between species were noted. In a further experiment filter-sterilized water extracts of each species were applied to spores on agar. Again, strong effects on spore germination and protonemal growth were noted. Patterns of inhibition differed between species and reflected those found in the previous experiment, indicating that the inhibition effect may be due to a water soluble chemical rather than the physical properties of the moss clumps. These studies present the first experimental evidence for the chemical inhibition of spores by mature plants. When taken together with previous reports of chemical interactions among protonemal systems, considerable ecological significance of these results is suggested.     

Germination and seed water status of four grasses on moss-dominated biological soil crusts from arid lands

Biological soil crusts dominated by drought-tolerant mosses are commonly found through arid and semiarid steppe communities of the northern Great Basin of North America. We conducted growth chamber experiments to investigate the effects of these crusts on the germination of four grasses: Festuca idahoensis, Festuca ovina, Elymus wawawaiensis and Bromus tectorum. For each of these species, we recorded germination time courses on bare soil and two types of biological soil crusts; one composed predominantly of the tall moss Tortula ruralis and the other dominated by the short moss Bryum argenteum. On the short-moss crust, the final germination percentage was about half of that on bare soil. Also, the mean germination time was 4 days longer on short-mosses than on bare soil. In contrast to the short-moss crust, the tall-moss crust did not reduce the final germination percentage but increased the mean germination time. Similar results were observed in the four grasses studied. To investigate the mechanism by which moss crusts affected germination, we analyzed the water status of seeds on bare soil and moss crusts. Six days after seeding, the water content of seeds on bare soil was approximately twice that of seeds on tall- or short-moss crust. Analysis of the time course of changes in seed weight and water potential in Bromus tectorum revealed that overtime seeds on tall mosses reached higher water content than those on short mosses. The increase in the water content of seeds on tall mosses occurred as the seeds gradually fell through the moss canopy. Taken together, our results indicate that biological soil crusts with distinct structural characteristics can have different effects on seed germination. Furthermore, this study revealed that a biological soil crust dominated by short mosses had a negative effect on seed water status and significantly reduced seed germination.     

Spore Germination and Rhizoid Differentiation in Onoclea sensibilis: A Two-Dimensional Electrophoretic Analysis of the Extant Soluble Proteins

Following a geometrically asymmetrical cell division during germination of spores of the fern Onoclea sensibilis L., the small cell differentiates into a rhizoid and the large cell divides to form the protonema. Using silver-staining of two-dimensional gels, we have examined the soluble proteins of spores during germination and of separated rhizoid protoplasts and protonemal cells. Of over 500 polypeptides followed, nearly 25% increased or decreased in prominence during spore germination and the initial phases of rhizoid elongation. Soluble proteins from purified protoplasts of young rhizoids were quantitatively different from those of protonemal cells and germinated spores. Nine polypeptides which appeared after cell division were substantially more prominent in rhizoid protoplasts than in whole germinated spores and have been putatively designated rhizoid-specific polypeptides. The differences in the soluble protein composition of young rhizoids and protonemal cells probably reflect the differential organelle distribution between the two cells as well as differential net protein synthesis in the cytoplasms of the two cells.     

Fungi infecting cultivated moss can also cause diseases in crop plants

Bryophytes (mosses) are non‐vascular plants inhabited by a large number of fungal species, but whether mosses can act as reservoirs of fungal pathogens of crop plants has gained little attention. A few moss species including the Sunagoke moss (Racomitrium japonicum; family Grimmiaceae) are found to have modern economical applications in uses such as greening of urban environments. In a previous study, we identified fungi causing symptoms of varying severity in the commercially grown Sunagoke moss. The aim of this study was to test whether the same fungal isolates are pathogenic to vascular plants. An isolate of Fusarium avenaceum lethal to the Sunagoke moss caused root and crown rot in barley (Hordeum vulgare) and reduced germination of tomato (Solanum lycopersicum) and carrot (Daucus carota) grown in the infested soil. An isolate of Cladosporium oxysporum causing mild symptoms in moss reduced growth and caused reddening and premature death of carrot seedlings. On the other hand, isolates of Alternaria alternata and Fusarium oxysporum lethal to the Sunagoke moss caused no detectable symptoms in any tested vascular plant, suggesting specialisation of these isolates to moss. Chloroplast repositioning was observed in the neighbouring cells towards the initially infected cell following infection with F. avenaceum and A. alternata in Physcomitrella patens (family Funariaceae), a model moss used to study microscopic symptoms. Infection of P. patens with a non‐virulent Apiospora montagnei isolate induced formation of papillae in the moss cells, indicating activation of host defence as described in vascular plants. Results suggest that mosses and vascular plants may be linked by a common microbial interface constituted by pathogenic fungi. The findings have epidemiological implications that have gained little previous attention.     

Arbuscular mycorrhizal structure and fungi associated with mosses

We investigated the colonization and diversity of arbuscular mycorrhizal (AM) fungi associated with 24 moss species belonging to 16 families in China. AM fungal structures, i.e. spores, vesicles, hyphal coils (including intracellular hyphae), or intercellular nonseptate hyphae, were found in 21 moss species. AM fungal structures (vesicles, hyphal coils, and intercellular nonseptate hyphae) were present in tissues of 14 moss species, and spores and nonseptate hyphae on the surface of gametophytes occurred in 15 species. AM fungal structures were present in 11 of the 12 saxicolous moss species and in six of the ten terricolous moss species, but absent in two epixylous moss species. AM fungal structures were only observed in moss stem and leaf tissues, but not in rhizoids. A total of 15 AM fungal taxa were isolated based on trap culture with clover, using 13 moss species as inocula. Of these AM fungi, 11 belonged to Glomus, two to Acaulospora, one to Gigaspora, and one to Paraglomus. Our results suggest that AM fungal structures commonly occur in most mosses and that diverse AM fungi, particularly Glomus species, are associated with mosses.     

Recruitment filtering by a moss layer disadvantages large-seeded grassland species

Calcareous grasslands are rich in biodiversity and thus receive much attention in nature conservation. In such grasslands, the formation of moss layers is perceived as a management problem. However, its impacts on the community level are complex, as not only inhibition but also facilitation of vascular plant recruitment occur. Possible filters of recruitment are shading by mosses, isolation from soil resources and the resulting desiccation. To understand how seed size and shape moderate moss effects, a combined glasshouse and field experiment was conducted in southern Germany. Seeds of 14 species from calcareous grasslands were sown either on top or underneath a moss layer, or on bare soil without moss. We determined the total number of emerged and established seedlings, i.e. the ones that survived until the end of the experiment. Both measures were reduced for most species sown on moss, while mortality was slightly enhanced by moss presence. Seed size explained a significant proportion of the moss effects on plant recruitment. Inhibitive effects on recruitment increased with seed size when seeds were placed on top of moss. When germinating underneath moss, the effect on emergence changed from negative in small-seeded plant species to positive in large-seeded species, but this effect was insignificant for establishment. The positive response in large seeds was probably due to their higher moisture requirements for imbibition, and lower dependency on light for germination. However, moss-seed-interactions were not affected by seed shape. Seedling establishment of plants with large seeds strongly depended on their initial position in moss, while small-seeded species showed no effect. Hence, moss layers constitute a selective recruitment filter by modifying seed penetration and hence germination conditions. This effect could increase beta diversity of vascular plant species in calcareous grasslands, and thus conservation should aim at intermediate and patchy moss abundance.     

Rapid top–down regulation of plant C:N:P stoichiometry by grasshoppers in an Inner Mongolia grassland ecosystem

Mosses play an integral role in the hydrologic regimes of ecosystems where they cover the soil surface, and thus affect biogeochemical cycling of elements influenced by soil oxidation–reduction (redox) reactions, including the plant growth-limiting nutrients, nitrogen and phosphorus (P). In rich fens where P often limits plant growth, we hypothesized that feedbacks between mosses and redox conditions would determine P availability to shallow-rooted forb species that constitute much of these wetlands’ unusually high plant species diversity. In a moss removal experiment in three fens, forb tissue P and microbial P were greater while anion exchange membrane (AEM) resin P was lower where mosses occurred than where they were removed, suggesting both higher availability and greater demand for P in moss-covered soils. Coupled physicochemical and biological mechanisms drove moss effects on P cycling, ultimately through effects on soil oxygenation or reduction: higher redox potential underlying mosses corresponded to greater microbial activity, phosphatase enzyme activity, and colonization by arbuscular mycorrhizal fungi (AMF), all of which can promote greater P availability to plants. These more oxidized soils stimulated: (1) greater microbial activity and root vigor; (2) correspondingly greater P demand via microbial uptake, forb uptake, and iron (Fe)-P reactions; and (3) greater P supply through soil and root phosphatase activity and AMF colonization. This work demonstrates that mosses improve vascular plant P acquisition by alleviating stresses caused by reducing conditions that would otherwise prevail in shallow underlying soils, thus providing a mechanism by which mosses facilitate plant species diversity in rich fens.     

杂色山雀对人工巢箱内苔藓类巢材的选择

2008年及2009年每年的3～8月,在辽宁省仙人洞国家级自然保护区对杂色山雀(Parus varius)人工巢箱内苔藓类巢材进行了收集和鉴定,发现巢中共有藓类植物7科9属。其中,小锦藓属(Brotherella)、青藓属(Brachytheccium)、棉藓属(Plagiothecium)及绢藓属(Entodon)所占比重较大。我们分别按照样方和苔藓群落采集了周围环境中的藓类植物,鉴定出7科8属的藓类植物;采集到35个苔藓群落,出现最多的是东亚小锦藓(B.fauriei)群落。结果显示,杂色山雀对苔藓的选择可能与苔藓的生物学特性、分布和数量有关。另外通过统计分析和比较得出,按照苔藓群落来采集的方式更适合本文的研究。     

五种藓类植物的孢子萌发与原丝体发育

本文对中华缩叶藓(Ptychomitrium sinense)、狭叶缩叶藓(P. linearifolium)、威氏缩叶藓(P．wilsonii)、葫芦藓(Funaria hygrometrica )和立碗藓(Physcomitrium sphaericum ) 5种国产藓类植物的孢子萌发和原丝体发育进行研究, 结果表明不同藓类孢子萌发和原丝体发育类型不同, 孢子萌发和原丝体发育方式与藓类植物的生态环境有关。     

中国藓类植物无性繁殖体的初步观察

无性生殖在苔藓植物的生活史中起着重要的作用,并且常通过各种无性繁殖体来完成。无性繁殖体的形态常被用来辅助鉴定一些不育的藓类植物。本文通过对38种藓类植物的无性繁殖体进行显微观察,结果显示：无性繁殖体在不同的藓类植物之间已经过多次演化;无性繁殖体的形态在种内是相对稳定的,且与其着生位置、配子体的分枝方式密切相关,而与植物的系统位置以及生境并无直接的关系;无性繁殖体的颜色与其胞壁的厚度以及表面纹饰密切相关。此外,无性繁殖体的产生常常与假根、原丝体有共存关系。在研究中发现,藓类植物的无性繁殖体主要包括原丝体芽胞、无性芽胞（叶生芽胞、中肋芽胞、枝生芽胞）、芽体、假根芽胞和假根状块茎;其中原丝体芽胞和无性芽胞最为常见。     

碎米藓属两种藓类植物孢子萌发与原丝体发育特征研究

为获取其孢子萌发类型与该属植物系统发育、生态选择以及生殖策略选择的相关性,该研究通过室内人工培养的方式,在微米量级下观察并描述了碎米藓属(Fabronia)碎米藓(F.pusilla)和东亚碎米藓(F.matsumurae)两种藓类植物孢子萌发、原丝体发育和配子体发生的过程.结果表明:(1)两种藓类植物孢子均为壁外萌发...     

银杏根系甲醇溶提物对离体培养条件下丛枝菌根真菌生长发育的研究

银杏根系甲醇溶提物对离体培养条件下丛枝菌根真菌生长发育的试验结果表明,银杏根系甲醇溶提物对离体条件下丛枝菌根真菌(Glonus mosseae,Gigaspora margarita)生长发育有明显的促进作用,能显著提高孢子萌发率,增加菌丝生长长度。与对照相比,浓度为20％～100％的甲醇溶提物均可显著促进丛枝菌根真菌的生长发育,80％甲醇溶提物效果最明显,银杏根系甲醇溶提物中含丰富的黄酮类化合物,溶提物中黄酮类物质的含量与甲醇洗脱剂的浓度有关,当浓度为80％时,黄酮含量最高,对银杏根系甲醇溶提物中黄酮类化合物含量与丛枝菌根真菌生长发育相关性分析发现,溶提物中黄酮类化合物含量与离体条件下丛枝菌根真菌孢子的生长发育表现为极显著的正相关关系,溶提物中黄酮含量越高,其对丛枝菌根真菌孢子的生长发育促进作用越大。     

上海市地面藓类植物的分布格局分析

在上海市选取20个公园和2个化工厂设立22个样点,对地面藓类植物进行野外样方调查、标本鉴定和数据统计．基于75种记录的藓类植物及其盖度数据,应用双向指示种分析法(TWINSPAN)和除趋势对应分析(DCA)分析其分布格局．结果表明,上海市地面藓类植物可聚类为3个样点组,样点组1为市中心2个公园和2个化工厂,共有藓类23种,总盖度最小(21．29％);样点组2为部分市中心公园和外围公园,共有藓类44种,总盖度37．94％;样点组3主要为外围公园和市郊公园,共有藓类49种,总盖度为49．66％．结果反映了藓类植物分布与不同生境,环境污染及人为干扰有一定相关性．