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.     

Surface structures of peridial cells ofGymnosporangium andRoestelia (Uredinales)

The surface structures of peridial cell walls (outer, side, and inner walls) of 40Gymnosporangium and 7Roestelia species were examined by scanning electron microscopy. These surface structures were classified into 10 types based on shape, size, and density of the processes. Surface structural types of each wall were stable within a species. Therefore, it is suggested that surface structure types of peridial cell walls could be used as important diagnostic characteristics ofGymnosporangium andRoestelia species. Contribution No. 140, Laboratory of Plant Pathology and Mycology, Institute of Agriculture and Forestry, University of Tsukuba.     

Biology and life cycle ofAtelocauda koae,an unusual demicyclic rust

Atelocauda koae, a rust of the native HawaiianAcacia koa, is considered as a demicyclic species, having spermogonial, aecial, and telial states, but is unusual in production of aeciospores simultaneously with teliospores rather than consecutively. Host inoculation with spores of each state separately confirmed that the life cycle was perpetuated by the telial state, but the aeciospores, while capable of germination and stomal penetration, did not produce detectable infection. This rust therefore behaves as a microcyclic species, and appears to be in evolutionary transition toward this reduced state. Teliospores produced vestigial, permanently attached basidiosopores which germinated to produce infective hyphae. The hyphae entered the host either through stomata or penetrated the epidermis directly, with the latter method being more common. Unusual nuclear associated with teliospore germination, in which meiosis occurs in more than one diploid nucleus was observed, in confirmation of an earlier study.     

Phylogenetic studies in <Emphasis Type="Italic">Ravenelia esculenta</Emphasis> and related rust fungi

Ravenelia esculenta Naras. and Thium. is a rust fungus, which infects mostly thorns, inflorescences, flowers and fruits of Acacia eburnea Willd. Aecial stages of the rust produce hypertrophy in infected parts. DNA of the rust fungus was isolated from aeciospores by ‘freeze thaw’ method. 18S rDNA was amplified and sequenced by automated DNA sequencer. BLAST of the sequence at NCBI retrieved 96 sequences producing significant alignments. Multiple sequence alignment of these sequences was done by ClustalW. Phylogenetic analysis was done by using MEGA 3.1. UPGMA Minimum Evolution tree with bootstrap value of 1000 replicates was constructed using these sequences. From phylogenetic tree it is observed that Ravenelia esculenta and the genus Gymnosporangium share a common ancestry, though Ravenelia esculenta is autoecious on angiosperm and the genus Gymnosporangium is heteroecious with pycnia, aecia on angiosperm and uredia, telia on gymnosperm. Two major clades are recognized which are based on the nature of aecial host (gymnosperm or angiosperm). These clades were also showing shift from pteridophytes to angiosperms as telial hosts. The tree can be interpreted in the other way also where there is separation of 14 families of Uredinales depending upon nature of teliospores, nature of aeciospores and structure of pycnia. These studies determine the phylogenetic position of Ravenelia esculenta among other rust fungi besides broad separation of Uredinales into two clades. These studies also show that there is phylogenetic correlation between molecular and morphological data. This is first report of DNA sequencing and phylogenetic positioning in genus Ravenelia from India.     

Life cycle of <Emphasis Type="Italic">Uromyces appendiculatus</Emphasis> var. <Emphasis Type="Italic">azukicola</Emphasis> on <Emphasis Type="Italic">Vigna angularis</Emphasis>

Field observations and inoculation experiments revealed that Uromyces appendiculatus var. azukicola has an autoecious and macrocyclic life cycle and produces spermogonia, aecia, uredinia, and telia on Vigna angularis var. angularis and V. angularis var. nipponensis. From inoculation experiments, it was suggested that this rust fungus has different host relationships from other varieties. Morphological examinations revealed that the characteristics of urediniospores and teliospores are different among varieties, although aeciospores are morphologically similar to each other.Contribution no. 182, Laboratory of Plant Parasitic Mycology, Institute of Agriculture and Forestry, University of Tsukuba, Japan     

Formation of nodular structures on the non-legumes Brassica napus,B. campestris,B. juncea and Arabidopsis thaliana with Bradyrhizobium and Rhizobium isolated from Parasponia spp. or legumes grown in tropical soils

Strains of Bradyrhizobium formed nodule-like structures on Arabidopsis and species of Brassica in pots with sandvermiculite and in glass tubes on a nitrogen-free mineral salts agar. Broad-host-range Rhizobium strains NGR234 from Lablab purpureus and NGR76 from Phaseolus vulgaris formed similar nodule-like structures on Brassica spp. The size of these structures on plants in pots were large, often reaching 10 mm in diameter.The frequency of inoculated Brassica plants in pots with nodule-like structures was 25–50%, depending on the inoculum strain. The inheritable nature of factors involved in the formation of the nodule-like structures was demonstrated when the structures occurred on 100% of inoculated B. napus seedlings derived from plants with the nodule-like structures.Nodule-like structures occurred without, but not with, the application of a cellulase-pectolyase-PEG treatment to the roots. Attempts to isolate Bradyrhizobium or Rhizobium from the nodule-like structures failed. Internal infection of these structures could not be detected using either the light or electron microscope. The inoculum strains of root-nodule bacteria were detected in high numbers in the rhizosphere of plants 5 months after inoculation. On agar plates bacterial colonies could be seen, with undiminished growth, over the surface of the agar extending to the root surface. However, ground root tissue of Brassica was toxic to Bradyrhizobium strains. This suggested that Bradyrhizobium strains would not survive after infecting the roots of Brassica spp. Nitrogen fixation was associated with high rhizosphere populations of Azospirillum and not with Bradyrhizobium induced nodule structures of Brassica spp.     

Fungal injury to seed tissues of Norway spruce,Picea abies (L.) Karst.

Norway spruce bore an abundance of cones in Finland in 2000, but these cones were often fungal-infected. The seeds had structural injuries that were revealed when seed samples were examined using light (LM) and a field emission scanning electron microscope (FESEM). Two main types of spores were found either in the tissues inside the seed coat or on the sarcotesta, the outermost layer of seed coat. The spores of Chrysomyxa pirolata appeared particularly in the nucellar tissue, where the cell walls were disintegrated at the middle lamellae and cytoplasm was disrupted. Degenerated remnants of fungal structures resembling aecial peridium were found close to aeciospores. The tissue of the megagametophyte differed also from that of a normal mature seed. Conidia of Thysanophora penicillioides were often encountered on the sarcotesta where the ordinary wax cover was missing. Fungal injury occurred in the nucellar layers that shelter the embryo and megagametophyte from desiccation and oxidation. Destruction of these structures together with rapid opening of the seed coat advance deterioration of seeds during storage and may cause unexpected economic losses in forest plant production.     

A study on the epidermal structure of <Emphasis Type="Italic">Periophthalmodon</Emphasis> and <Emphasis Type="Italic">Periophthalmus</Emphasis> mudskippers with reference to their terrestrial adaptation

Epidermal structures of three species of Periophthalmus (Ps.) and two species of Periophthalmodon (Pn.) were investigated in relation to their lifestyle. All species of both genera lack a dermal bulge, which species of other two oxudercine genera, Boleophthalmus and Scartelaos, have in their epidermis. In Periophthalmus and Periophthalmodon species, which are highly terrestrial, the middle cells are well developed in the epidermis and the capillaries are distributed in the surface of the epidermis on the head and dorsal body. In Periophthalmus species and Pn. septemradiatus, the capillaries and blood vessels are also distributed in the epidermis of the abdomen, superficially in Ps. modestus and deeply in other species. In Ps. modestus, the capillaries are also densely distributed on the surface of the epidermis in the caudal area, whereas in other species, the epidermal capillaries and blood vessels of this area are located deep with a very low density. In Pn. schlosseri, the epidermal capillaries are not found in either the abdominal area or caudal area. A comparison of the distribution of epidermal capillaries among Boleophthalmus, Periophthalmodon, Periophthalmus, and Scartelaos species revealed that the skin makes a larger contribution to respiration in the species having a more terrestrial lifestyle. Goblet mucous cells are completely lacking in Periophthalmus species, whereas slimelike materials were often found on the skin surface of Periophthalmus species. This finding suggests that Periophthalmus species have some unknown mechanism for producing mucus. In Pn. schlosseri, exposure of the dense capillary net on the surface of the head is likely to increase cutaneous respiration, but it also makes the fish an attractive target of bloodsucking insects.Supplementary material to this paper is available in electronic format at http://dx.doi.org/10.1007/s10228-003-00173-7     

Chromosome numbers and rust susceptibility as taxonomic criteria inRosaceae

BothNeuradoideae andChrysobalanoideae seem rust-free. TheSpiraeoideae andPomoideae are heavily susceptible toGymnosporangium rusts. While thePrunoideae resemble theRosoideae in being vulnerable to attacks ofPuccinia species, they are additionally susceptible toTranzschelia andThekopsora, whereas theRosoideae are characteristically afflicted byPhragmidium.—It is suggested (a) to treat theChrysobalanoideae as a separate family (Chrysobalanaceae), (b) to transferDryas from theRosoideae-Potentilleae-Dryadinae to theRosoideae-Cercocarpeae, and (c) to divide theRosoideae into two main groups of tribes: (i) the rust-freeKerrieae andCercocarpeae with x = 9, and (ii) the rust-susceptiblePotentilleae, Ulmarieae, Roseae andSanguisorbeae with x = 7.     

Keratinolysis and its morphological expression in hair digestion by airborne fungi

The morphological expression of keratinolysis in fungi isolated from the air of Torino (98 isolates belonging to 36 species) was studied. Light microscopy on whole material and on semithin sections, as well as scanning electron microscopy was used. There were 19 keratinolytically active species, with seven in the genusChrysosporium (C. indicum, C. keratinophilum, C. pannicola, C. tropicum, C. an.Arthroderma cuniculi, C. an.Pectinotrichum llanense, C. an.Renispora flavissima), four in the genusMalbranchea (M. arcuata, M. fulva, M. sulphurea, M. st.Uncinocarpus reesii), and three in the genusTrichophyton (T. mentagrophytes, T. rubrum, T. terrestre). In addition there wereAphanoascus fulvescens, Beauveria bassiana, Geomyces pannorum v.pannorum, Gymnoascus umbrinus andMyceliophthora vellerea. Most of these species were capable of developing structures related to surface erosion and radial penetration contemporaneously. HoweverGymnoascus umbrinus, Myceliophthora vellerea, an isolate ofC. indicum, C. tropicum andTrichophyton mentagrophytes demonstrated only surface erosion. Different isolates of one species can vary in their production of invasive structures and in degree of keratinolytic activity. Thus such activity, like many biochemical activities of fungi, does not appear to be a constant or rigorously species-specific character.     

五种红树植物叶片结构的比较研究

以木榄(Bruguiera gymnorrhiza)、桐花树(Aegiceras corniculatum)、拉关木(Laguncularia racemosa)、海芒果(Cerbera manghas)、杨叶肖槿(Thespesia populnea)五种红树植物为材料,采用常规石蜡切片法对它们的叶片横切面结构进行显微观察,比较真红树植物和半红树植物叶片结构的特点及变化规律,研究红树植物叶对盐浸环境的适应性。结果表明:除杨叶肖槿为异面叶、掌状网脉外;拉关木为等面叶、羽状脉,其它三种植物为异面叶、羽状网脉;五种材料具4级叶脉,3级、4级脉具明显维管束鞘。木榄、桐花树、拉关木、杨叶肖槿1级脉为半周韧无限维管束,海芒果1级脉为外韧无限维管束。五种材料叶肉具有分泌腔,除海芒果外,具有含晶体细胞;木榄、桐花树有内皮层,拉关木有贮水组织;桐花树、海芒果有含单宁细胞;桐花树、拉关木、杨叶肖槿有盐腺。这五种植物的叶片结构体现出不同植物对盐浸环境适应性的特征。相比较而言,真红树植物的特化结构较半红树植物多。     

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.     

SEM investigations of the larval development of Imnadia yeyetta and Leptestheria dahalacensis (Crustacea: Branchiopoda: Spinicaudata)

This paper presents a SEM documentation of the larval development of the two most abundant Austrian conchostracan species, Imnadia yeyetta (Limnadiidae) and Leptestheria dahalacensis (Leptestheriidae). As in several previously examined spinicaudatan species, five larval stages were documented: Nauplius 1, Nauplius 2, Metanauplius, Peltatulus, and Heilophore. Additionally, three postlarval stages of L. dahalacensis and the first larval instars of Eoleptestheria ticinensis and Limnadia lenticularis are shown and compared with the examined stages. Species identification of conchostracan larval stages is possible by using surface structures, and using SEM methods, except for L. lenticularis which can be identified more easily on the characteristic shape of the labrum.     

An attachment tip and pili-like structures in insect- and plant-pathogenic spiroplasmas of the class Mollicutes

Ultrastructural studies using scanning electron microscopy (SEM), negative-staining transmission electron microscopy (TEM), and thin-sectioning TEM on four species of Spiroplasma, in vitro and/or in vivo, indicated that their helices commonly possess one tapered end (tip structure) and one blunt or round end. These tip structures appeared morphologically different from the rest of the helix, exhibiting an electron-dense conical or rod-shaped core. In thin sections of the midgut of the leafhopper Dalbulus elimatus, the tip structures of Spiroplasma kunkelii in the midgut lumen were mostly aligned between microvilli, perpendicular to the apical plasma membrane of epithelial cells. These tip structures appeared frequently attached or closely apposed to the plasma membrane, in which cup-shaped invaginations close to the tips were observed. Pleomorphic forms of spiroplasma, enclosed in membranous vesicles, were found in the cytoplasm of the midgut epithelial cells. These findings suggest that the tip structure may be involved in the orientation and attachment of spiroplasma helices in relation to their host cells, and thus may be functionally comparable to the attachment organelle of mycoplasmas. Additionally, pili-like structures were observed by negative-staining TEM on the surface of Spiroplasma melliferum, and in thin sections of S. kunkelii infecting the leafhopper vector Dalbulus gelbus. Abbreviations CSS Corn stunt spiroplasma - SEM Scanning electron microscopy - TBS Tris-buffered saline - TEM Transmission electron microscopy     

三种厚朴叶绿体基因组的比较研究

为了深入发掘日本厚朴、厚朴、凹叶厚朴叶绿体基因组差异,筛选厚朴优良性状候选基因,开展三种厚朴的分子遗传研究,该文利用Illumina HiSeq高通量测序平台首次对日本厚朴叶绿体进行测序、组装,并与已有的厚朴、凹叶厚朴叶绿体基因组共同注释,获得三个物种叶绿体基因图谱,筛选出三个基因组中的差异基因,又与同科中11个亲缘物种进行叶绿体基因组比对,构建NJ遗传树。结果表明：(1)日本厚朴叶绿体基因组的Clean Reads为19 791 019,Q30为91.33%,组装后基因组全长160 051 bp, GC含量为39.2%,含tRNA 37个,rRNA 8个。(2)比对分析发现三种厚朴具有相似的IR、LSC和SSC结构,以及GC含量和tRNA数量,但编码基因种类和数量、内含子和外显子的数量和结构等存在差异。(3)日本厚朴的功能基因数目较厚朴、凹叶厚朴分别多6个和4个,主要分布于LSC区和IR区,涉及核糖体大亚基、核糖体小亚基和未知功能基因类群。(4)系统发育分析结果进一步显示日本厚朴与凹叶厚朴亲缘关系较近,其次是厚朴。该研究表明日本厚朴具有更丰富的叶绿体基因组结构、组成和变异特征,是其适...     

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.     

Soil mycoflora from trufflè native areas of Saudi Arabia

Soil fungi of areas in the North-Eastern region of Saudi Arabia where truffles are native were surveyed. Forty-three species of fungi belonging to twenty genera were isolated. Most were recovered from soils underneath or around truffle ascocarps: thirty species from soil under the surface of Tirmania nivea ascocarps, twenty-four from Terfezia boudieri soil and twenty species each from Tirmania pinoyi and Terfezia claveryi soils. Rhizosphere soil of Helianthemum lippi, on the other hand, yielded twenty-four fungal species while only fourteen fungal species were found in soil without vegetation. The total counts of fungi/g soil were highest in soils from the under surface of truffles, followed by rhizosphere soil, with the lowest in soils without vegetation.     

Trichoderma species form endophytic associations within Theobroma cacao trichomes

Trichoderma species are usually considered soil organisms that colonize plant roots, sometimes forming a symbiotic relationship. Recent studies demonstrate that Trichoderma species are also capable of colonizing the above ground tissues of Theobroma cacao (cacao) in what has been characterized as an endophytic relationship. Trichoderma species can be re-isolated from surface sterilized cacao stem tissue, including the bark and xylem, the apical meristem, and to a lesser degree from leaves. SEM analysis of cacao stems colonized by strains of four Trichoderma species (Trichoderma ovalisporum-DIS 70a, Trichoderma hamatum-DIS 219b, Trichoderma koningiopsis-DIS 172ai, or Trichoderma harzianum-DIS 219f) showed a preference for surface colonization of glandular trichomes versus non-glandular trichomes. The Trichoderma strains colonized the glandular trichome tips and formed swellings resembling appresoria. Hyphae were observed emerging from the glandular trichomes on surface sterilized stems from cacao seedlings that had been inoculated with each of the four Trichoderma strains. Fungal hyphae were observed under the microscope emerging from the trichomes as soon as 6 h after their isolation from surface sterilized cacao seedling stems. Hyphae were also observed, in some cases, emerging from stalk cells opposite the trichome head. Repeated single trichome/hyphae isolations verified that the emerging hyphae were the Trichoderma strains with which the cacao seedlings had been inoculated. Strains of four Trichoderma species were able to enter glandular trichomes during the colonization of cacao stems where they survived surface sterilization and could be re-isolated. The penetration of cacao trichomes may provide the entry point for Trichoderma species into the cacao stem allowing systemic colonization of this tissue.     

Ecological significance of light controlled seed germination in two contrasting tropical habitats

Summary The effects of temperature, photoperiod, phytochrome photoreversion and the response to a R/FR ratio gradient were investigated in seeds of four species from two contrasting tropical habitats; two species from a rain forest (Cecropia obtusifolia and Piper umbellatum) and two from a high altitude lava field covered by low vegetation (Buddleja cordata and Chenopodium ambrosioides). In the rain forest seed species the photoblastic response seems to be adapted to light quality changes due to canopy destruction, on the other hand, the lava field seed species seem to be adapted to instantaneous light stimulus such as would be produced by the sudden exposure of a buried seed to the soil surface light environment.     

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.