A new rust species ofRoestelia onSorbus collected in China

A rust species ofRoestelia onSorbus collected in China is newly described asR. echinulata. This species is morphologically different from the otherRoestelia spp. and aecial stages ofGymnosporangium species in surface structures of aeciospores and peridial cells. Contribution No. 141, Laboratory of Plant Pathology and Mycology, Institute of Agriculture and Forestry, University of Tsukuba.     

Aeciospore surface structures ofGymnosporangium andRoestelia (Uredinales)

Aeciospore surface structures of 40Gymnosporangium species and 7Roestelia species were investigated with a scanning electron microscope. The surface structures of aeciospores were classified into 12 types on the basis of shape and size of processes. Surface structures of the aeciospores were stable within each species. Therefore, it is suggested that surface structures of aeciospores could be used as an important diagnostic criteria in identifyingGymnosporangium andRoestelia species. Contribution No 139, Laboratory of Plant Pathology and Mycology, Institute of Agriculture and Forestry, University of Tsukuba.     

Morphology and development of Nigrosabulum globosum, a cleistothecial coprophile in the Bionectriaceae (Hypocreales)

Recent DNA sequence analyses indicated that Nigrosabulum globosum is a cleistothecial representative of the Bionectriaceae in the Hypocreales, but morphological characters supporting this relationship are unknown. Using light and electron microscopy we followed the development of the ascomata of this species, from the formation of gametangia through to the development of mature ascospores, and observed a series of characters that confirmed its hypocrealean affinities. These included the formation of a gel-filled centrum during early stages of ascoma development, the subsequent appearance of hyaline peridial tissue enclosed within a layer we interpret as representing a melanized uniloculate stroma, apically derived paraphyses, and an ascogenous system that gives rise to asci that were both cylindrical to clavate and globose. Ascospores, previously reported to be smooth, were ornamented with a honeycomb-like reticulum and were able to germinate within the ascoma. The carbonaceous outer (stromatic) walls of the mature, grit-like cleistothecia indicate possible resistance to UV radiation and desiccation. Furthermore, the complement of germinated ascospores would enable mature ascomata to function as propagules that could quickly initiate new growth when transferred to fresh substrate. Our reexamination of N. globosum also provides data that support the hypothesized close relationship with other bionectriaceous, cleistothecial coprophiles, i.e., species of Hapsidospora, and Bulbithecium in particular.     

Development and dehiscence of the cephalothecoid peridium in Aporothielavia leptoderma shows it belongs in Chaetomidium

The development of the cephalothecoid peridium of Aporothielavia leptoderma was examined using light and electron microscopy. Early stages in ascoma initiation were consistent with previous reports for other species in the Chaetomiaceae. However, as young cleistothecia increased in size, clusters of peridial cells in the outer textura angularis elongated in a radial pattern around a central cell or cell cluster to form rosettes of relatively thick-walled segments that marked the central areas of incipient cephalothecoid plates. The external flank along median portions of the radial cells became thin walled and swelled outwards so that each plate became concave and was separated from adjacent plates by a more or less circular to polygonal ridge of knuckle-shaped swellings. When dry, mature peridia split apart along some of the ridges demarcating individual plates but an internal mechanism for liberating ascospores from the confines of the ascoma was not observed. Physical disturbance of mature cleistothecia by beetles, when enclosed together in a Petri dish, shattered the peridia, liberating the ascospores. Smaller insects were unable to cause disarticulation of the cephalothecoid plates. Because of the presence of an apical germ pore in the ascospores and morphological similarity to Chaetomidium arxii, the new combination Chaetomidium leptoderma (syn. Thielavia leptoderma) comb. nov. is proposed.     

New species and records of saprophytic ascomycetes (Myxotrichaceae) from decaying logs in the boreal forest

Decayed wood from fallen white spruce (Picea glauca) and trembling aspen (Populus tremuloides) collected in northeastern Alberta, Canada, was the source of new isolates of species in the ascomycete generaGymnostellatospora andPseudogymnoascus. In addition to new reports ofG. japonica, G. frigida andP. roseus, two new species are described.Gymnostellatospora canadensis sp. nov. resemblesG. japonica but differs in producing brown ascomata and in the formation of an arthroconidial anamorph.Gymnostellatospora subnuda sp. nov. is distinct in lacking differentiated peridial hyphae.Gymnostellatospora alpina was not found in decayed wood but is reviewed based on extralimital material. A dichtomous key to the five species ofGymnostellatospora is provided.     

Cell walls of algae in the volvocales: Their sensitivity to a cell wall lytic enzyme and labeling with an anti-cell wall glycopeptide ofChlamydomonas reinhardtii

A cell wall lytic enzyme (gamete wall-autolysin) and a polyclonal antiserum raised against one of the major cell wall glycopeptides ofChlamydomonas reinhardtii were used to study their cross-reactivities with the cell walls of variety of members of the Volvocales. Lytic enzyme was able to digest completely the cell walls of five species ofChlamydomonas (C. reinhardtii group), six species ofGonium and two species ofAstrephomene. The colonial structures ofGonium andAstrephomene were broken into individual cells by exposure to the enzyme and protoplasts were then formed. These organisms also showed a strong cross-reactivity with anti-cell wall glycopeptide by an indirect-immunofluorescence test. The cell walls ofChlamydomonas angulosa, Dysmorphococcus globosus, Pandorina morum, Eudorina elegans, Volvulina steinii, Pleodorina california andVolvox carteri all showed a strong cross-reactivity to the antibody, although they were insensitive to the lytic enzyme. Many other species ofChlamydomonas, Carteria crucifera, Chlorogonium elongatum, Polytoma uvella, Haematococcus lacustris, Lobomonas piriformis, Phacotus lenticularis, Pteromonas angulosa, Stephanosphera pluvialis, andPyrobotrys casinoensis had cell walls which were resistant to the enzyme and showed no or weak cross-reactivity with the antibody. Based on the results, a possible evolutionary sequence from a unicellular relative ofC. reinhardtii to the multicellular algae is discussed.     

Leaf anatomy inCaesalpinia andHoffmannseggia (Leguminosae,Caesalpinioideae) with emphasis on secretory structures

Leaflets of 65 species ofCaesalpinia s.l. and seven species ofHoffmannseggia were studied in clearings supplemented by resin sections and scanning electron microscopy. Three types of secretory structure occurred among 46 species; in 43 species they were distributed mutually exclusively (external glands: 8 species; internal cavities: 5 species; idioblastic cells: 30 species); three other species each had two types. Species with secretory structures conform mostly to proposed subgenera and informal groups. Other unusual features were external glands with internal spaces, thickened walls or conspicuous localized wall thickenings in epidermal cells or mesophyll cells of certain species, and differentially stained epidermal cells surrounding stomata. Prismatic crystals predominate but druse crystals also occur.     

The cell wall of Chlamydomonas reinhardtii gametes: Composition,structure and autolysin-mediated shedding and dissolution

The cell walls of Chlamydomonas gametes are multilayered structures supported on frameworks of polypeptides extending from the plasma membrane. The wall-polypeptide catalogue reported by Monk et al. (1983, Planta 158, 517–533) and extended by U.W. Goodenough et al. (1986, J. Cell Biol. 103, 405–417) was re-evaluated by comparative analysis of mechanically isolated cell walls purified from several strains. The extracellular locus of wall polypeptides was verified by in vivo iodogen-catalysed iodination and by autolysin-mediated elimination of the bulk of these polypeptides from the cell surface. Three (w15, w16, w17) and possibly four (w14) polypeptides were located to the most exterior aspect of the wall because of their susceptibility to Enzymobeadcatalysed iodination and their retention by a cell-wall-less mutant. The composition of shed walls stabilised with ethylenediaminetetraacetic acid during natural mating and kinetic analysis of the dissolution of walls purified from a bald-2 mutant demonstrated the rapid and specific destruction of polypeptide w3. Differential solubilisation of wall polypeptides occurred after loss of w3. Wall dissolution, characterised by the generation of fishbone structures from the W2 layer, gave as many as four additional polypeptides. Charged detergents and sodium perchlorate extracted a comparable range of polypeptides at room temperature from mechanically isolated walls, i.e. components of the W4–W6 layers, hot sodium dodecyl sulphate solubilised framework polypeptides, while reducing agent was required to solubilise the W2 layer. A model of wall structure is presented.Abbreviations DTE dithioerythritol - EDTA ethylenediaminetetraacetic acid - M_r relative molecular mass - SDS-PAGE sodium dodecyl sulphate-polyacrylamide gel electrophoresis - Tris 2-amino-2-(hydroxymethyl)-1,3-propanediol     

Structure and possible function(s) of charasomes; complex plasmalemma-cell wall elaborations present in some characean species

Summary Charasomes, complex membrane structures, were found along the longitudinal walls of internodal and lateral branch cells ofChara corallina andC. braunii, but not along their transverse walls or in other cell types. Charasome-complexes were larger and more numerous in the lateral branch cells than in internodal cells. InC. corallina, a dioecious species, especially large elaboration of charasome material occurs in the lateral branch cells of the female plant, sometimes reaching a cross-sectional width which is as great as that of the adjacent cell wall. Chara internodes transport hydroxyl (OH^–) out of the cell and bicarbonate (HCO₃ ^–) into the cell. Spatial distribution of charasomes along the cell was examined with respect to these transport phenomena, which occur at specific identifiable regions along the cell. Charasome-complexes were always found in regions in which HCO₃ ^– transport occurs but were often fewer, reduced in size or absent in areas of OH^– efflux.Nitella flexilis exhibited similar patterns of OH^– and HCO₃ ^– transport along the cell; however, there was a complete absence of charasomes. Ultrastructural examinations onNitella translucens indicated that charasomes were also absent in this species. The observation that charasomes are present in both transport regions ofChara but are totally lacking in the twoNitella spp. indicates that the charasome-complex is not involved in transport of either substance. Other possible functions for the charasomes, including a role in osmoregulation, are discussed.Charasome substructure is the same in bothChara species, consisting of a mass of short (50 nm average length) anastomosing tubules (30 nm average diameter) derived from the plasmalemma. The interior of the tubules is open to the cytoplasm while the area surrounding the tubules is ultimately open to the wall and thus can be considered to be wall space. Charasomes are quite variable in size and shape, but are roughly globular, with the bulk of the structure projecting into the cell cytoplasm. Tubular components of the charasome were sometimes seen to extend into the microfibrillar wall matrix. A three dimensional model of the charasome-complex presented details the great complexity of this membrane system.     

A new species of petalosporus

Summary A new species ofPetalosporus, P. anodosus, is described and illustrated. Two isolates representing this species were isolated from dung in California. The new species differs from the only other species of the genus,P. nodulosus, by the lack of thick-walled peridial hyphae with enlargements at the septa and by the absence of disarticulation of peridial elements. Peridial hyphae inP. anodosus have walls which are somewhat thickened and the cells are often variable in diameter. Conglomerate ascospores usually assume the petaloid arrangement characteristic of the genus.     

A new variety ofMyxotrichum ochraceum from Japanese soil

Myxotrichum ochraceum var.frigidum, a new variety ofMyxotrichum, is described and illustrated from the material from Japanese soil. It is morphologically characterized by dull green to black ascomata with a yellow-orange centrum, peridium consisting of a fragile hyphal network, peridial hyphae with internal coiled branches and short spine-like appendages, pale yellow fusiform striate ascospores, and the absence of an anamorph. The new variety primarily differs from the type variety in the absence of elongate appendages. A key to all accepted species of the genus is revised.     

Frequency and structure of spinae on Chlorobium spp.

Several Chlorobium species have been observed to possess spinae. Spinae are non-prosthecate, helically wound, rigid structures that extend from the outer bacterial cell surface into the external environment. Spinae length was variable within and between Chlorobium species. Spinae width was fairly consistent within species but varied between species (39.4 ± 2.6 nm to 82.6 ± 8.0 nm). The number of spinae per cell varied. The spinae did not penetrate the bacterial cell envelope and were randomly located on the cell surface. Spinae were not geographically restricted. The observation of spinae on pure cultures of Chlorobium spp. maintained for 25–30 years suggests that spinae may be of significant use to the cell.     

Pectate distribution and esterification in Dubautia leaves and soybean nodules,studied with a fluorescent hybridization probe

Carbohydrate-hybridization probes (Vreeland and Laetsch, 1989, Planta (177, 423–434) were used to localize the homogalacturonan (pectate) component of pectins in the cell walls of leaves and soybean root nodules. Leaves of two species of the dicotyledon Dubautia were compared; these species contain much pectin but differ in their tissue water relations with respect to their cell-wall properties. Maturation of the primary cell walls in nodules was studied in the Bradyrhizobium japonicum-Glycine max symbiosis. Probe labelling was based on the divalent-cation-mediated association between pectate in tissue sections and fluorescein-conjugated pectate fragments. Pectate was also labelled by mixed-dimer formation with fluorescent polyguluronate derived from alginate. The specificity of the probe for unesterified polygalacturonate was indicated by increased cell-wall labelling after chemical or enzymatic deesterification of tissue sections, in contrast to elimination of labelling by chemical esterification. Postfixation of tissue sections improved retention of soluble pectate. Pectate differences were found in the leaves among cell types, in degree of esterification, and between plant species. The cell walls of soybean nodules were strongly labelled by the pectate probe in nodules one week and three weeks after infection. Pectate was more highly esterified in the central infected zone than in the surrouding cortex. Within the infected zone, walls of uninfected cells and infected cells were similarly labelled by the pectate probe. The results indicate that the pectate molecular probe provides detailed information on pectate distribution at the cellular level for investigations of cell-wall structure, development and physiology.Abbreviations EDTA ethylenedinitrilotetraacetic acid (ethylenediaminetetraacetic acid) - NMR nuclear magnetic resonance spectroscopy - TTB 1,3,5-triazido-2,4,6-trinitrobenene     

Analysis of the fruit surfaces in Bupleurum L. (Umbelliferae) with SEM

20 Bupleurum L. taxa were investigated for micromorphological typology of the fruit surfaces with SEM. Considerably different types of sculpturing at species and subspecies level and similarities between related taxa were observed. A dichotomic key was prepared using the diagnostic surface patterns. Reticulate (sect. Bupleurum), rugose (sect. Aristata Godron subsect. Aristata) and rugulose-colliculate-verrucate (subsect. Juncea Briq.) types of surface structures were distinguished. Micromorphological characteristics may be valuable additional taxonomical criteria for the delimitation of infrageneric groups of species.     

Spiromastix saturnispora,a new species from indonesian soil

Spiromastix saturnispora, isolated from a soil sample collected from central Java in Indonesia, is described and illustrated as a new species. The new species was compared with the type ofSpiromastix, S. warcupii, and is similar in having brownish ascomata with a peridium of a loose network of delicate hyphae, peridial appendages which are curved in the manner of a scimitar and never completely coiled, and the absence of an anamorph. The ascospores ofS. saturnispora are characterized as large oblate, 3.2–4.8 × 2.5–3µm, punctate, and with an equatorial rim, which serves to distinguish the species fromS. warcupii and other known species.     

Seed morphology in Southern AfricanOrchidoideae (Orchidaceae)

The seed morphology of 151 species of Southern AfricanOrchidoideae (Orchideae andDiseae; sensuDressler 1981) was studied by means of scanning electron microscopy. Two different seed types were found. (1) In the majority of species the seeds are minute and fusiform. The seed coat is made up of comparatively few concave and elongate testa cells with straight or slightly undulate and generally unthickened anticlinal cell walls. The seed type was here termed Satyrium-type. While most species are very similar in the ornamentation of the periclinal walls of their seed coat, considerable variation was found inHolothrix where two distinct groups can be recognized in this respect. (2) A remarkably different seed type was observed inDisa uniflora and three apparently closely related species (Disa uniflora-type), where large balloon-like seeds occur. Their seed coat consists of convex cells with undulate anticlinal walls. It is suggested that this seed type is a derived condition and has evolved in adaptation to the specialized habitat alongside streams. The possibility of hydrochory in these four species is briefly discussed.     

Characterization of a sperm lysin of Volvox carteri

Summary A cell-wall degrading enzyme has been isolated from mature sperm packets of the green flagellate Volvox carteri (Poona strain). This sperm lysin (S-lysin) is a Ca²⁺-dependent protease of 34 kDa with an essential serine group in its active centre. Neither SH group-blocking reagents nor transition metal chelators inhibit its action. S-lysin degrades the hydroxyproline-rich glycoprotein structures of the cell walls of sheath cells and gonidia (eggs) of vegetative and sexual spheroids in a characteristic manner. In asexual spheroids the somatic envelope is totally disintegrated, whereas in sexual spheroids pores are formed by local lysis at sites of adjacent eggs. Although S-lysin is very similar to the G-lysin of the closely related Chlamydomonads, it is species specific and does not attack the mother or daughter cell walls of Chlamydomonas reinhardtii. S-lysin resembles the aerosin of animal sperm cells in some aspects of its action.Dedicated to Professor Richard C. Starr on the occasion of his 65th birthday. He called the piper and gave the tune     

中国瓜馥木属植物叶片结构的解剖观察

采用叶片表皮离析法、扫描电镜和石蜡制片法,研究了中国分布的番荔枝科瓜馥木属19种植物叶片的形态结构。结果表明:瓜馥木属叶片形态和结构具有较多的相似性,如叶片表皮均具有2-多个细胞的单列丝状毛,表皮细胞内具有一个晶簇,气孔器均为平列型,只分布在叶片的远轴面,远轴面的表皮细胞平周壁形成一个乳突,叶片主脉的维管组织除具有正常的维管组织外,还具有一个小的副维管束等,这些特征有助于区分番荔枝科植物的属间关系,支持瓜馥木属是一个很自然的类群。但叶片表皮毛的形态及分布,表皮细胞的形状、叶肉中栅栏组织和海绵组织的结构、远轴面的乳突大小以及叶主脉维管组织的细微结构则具有种间差异。尤其有助于区分小萼瓜馥木和黑风藤、广西瓜馥木和独山瓜馥木、上思瓜馥木和东方瓜馥木等形态相似、难以区分的植物种类。该研究结果为该属的系统研究和种间正确区分提供了重要资料。     

Arbuscular mycorrhizas on Athyrium yokoscense and A. niponicum grown at a lead-contaminated site

To investigate the occurrence of arbuscular mycorrhizas (AM) and their morphological types, four Athyrium yokoscense and five A. niponicum individuals were collected at a lead-contaminated site. Three of the A. yokoscense and four of the A. niponicum formed AM structures. However, the percentage of AM formation within both species differed significantly among individuals. Morphological types of most AM structures were the Paris-type, except for one A. yokoscense that formed both Paris-type and Arum-type-like structures in different parts of the same root section. These results demonstrate that the two Athyrium species form AM associations in lead-contaminated soil.     

Comparative studies on the mycorrhization of Larix decidua and Picea abies by Suillus grevillei

Summary Mycorrhization of Picea abies has been achieved, for the first time, with six strains of Suillus grevillei by a new culture method, using activated charcoal paper and liquid medium as a substrate. Mycorrhization of P. abies and Larix decidua was compared, and the process was found to be significantly different in the two tree species. S. grevillei is not incompatible with P. abies, but it forms mycorrhizae more readily with L. decidua. Hyphal growth was clearly stimulated on the surface of roots of Larix but retarded on Picea. A well organized Hartig net was formed with both tree species, but wall protuberances were frequently observed on the outer cell walls of Picea cortex cells when the Hartig net was not fully developed. No conspicuous cell wall reactions occurred in Larix roots. Cell wall protuberances may be comparable to those in transfer cells and are interpreted as an alternative to Hartig net development. Anatomical differences between roots of Larix and Picea, and physiologically active substances such as recognition factors on the root surfaces, are discussed with respect to their responsibility for the different reactions of S. grevillei.