Selection and characterization of crystalviolet-and malachite-green-resistant mutants in Volvariella volvacea

Volvariella volvacea, the straw mushroom, has long been considered as a primary homothallic species. However, great variations in monosporous isolates have ralsed a considerable debate on the sexuality pattern of this edible Basidiomycete fungus. Because clamp connection is absent in V. volvacea, the production of genetically marked strains offers a possible means of resolving this problem. In this study, ultraviolet irradiation of basidiospores and mycellal fragments was used to induce crystal-violet- and malachite-green-resistant mutants. Cross-resistance to crystal violet and malachite green occurred between both classes of mutant. The difficulties of inducing mutants in this multinucleate fungus and the significance of mutant markers are discussed.The authors are with the Department of Biology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.     

Biological species and morphological characteristics ofArmillaria mellea complex in Hokkaido:A. sinapina and two new species,A. jezoensis andA. singula

Three intersterility groups ofArmillaria mellea sensu lato were discovered by examining all pairwise combinations of monosporous isolates of basidiomes collected in Hokkaido. One of them, group IV, was identified asA. sinapina by mating it with tester strains. Two new species, groups III and V, were namedA. jezoensis andA. singula, respectively. Their morphological forms and the ecology of their basidiomes are described.     

A note onArmillaria mellea subsp.nipponica subsp. nov. in Japan

Basidiomes of homothallicArmillaria mellea complex were discovered in the forests of Hokkaido. Their monosporous isolates showed partial compatibility with North AmericanA. mellea s. str. haploid testers. The morphological characteristics of basidiomes differed from other temperateA. mellea s. str. in several aspects. Here, JapaneseA. mellea s. str. is reclassified asA. mellea subsp.nipponica and its basidiome morphologies and habitats are described.     

Saprolegnia semihypogyna sp. nov., a saprolegniaceous oomycete isolated from soil in Japan

Saprolegnia semihypogyna, a saprolegniaceous oomycete (Saprolegniales, Oomycetes), is described based on two strains isolated from soil samples collected in Japan. It is characterized by having a new combination of sexual characters in the genus Saprolegnia, namely, producing mostly monosporous oogonia with subeccentric oospores and semihypogynous or androgynous antheridial branches. The species is morphologically similar to Scoliolegnia subeccentrica, although the oogonial wall of the former is smooth and that of the latter is densely ornamented. Morphological comparison of the two species indicates that the generic status of the genus Scoliolegnia is questionable. Received: February 22, 2001 / Accepted: September 5, 2001     

Two ultrastructural aspects of the trichospore of Pennella angustispora (Harpellales): canals in the sporangiospore cell wall and appendage formation

Ultrastructure of the trichospore (monosporous sporangium) and its generative cell of Pennella angustispora was observed by electron microscopy. In the sporangiospore, both poles of the cell wall were thickened in appearance with canals. Appendages developed longitudinally along the wall of generative cell before the formation of a septum that would delimit between the trichospore and its generative cell. Received: May 2, 2001 / Accepted: September 28, 2001     

Variation in Helminthosporium gramineum Rab., the incitant of leaf stripe of barley

Thirty-four monosporous isolates ofH. gramineum Rab., the incitant of leaf stripe of barley, were divided in seven categories on the basis of morphological and cultural characters. Seventy-three Indian and American varieties of barley were tested for their reaction against the seven isolates. Detailed observations on prevalence and severity have been taken and a new method has been developed for calculating infection value in each case. There are distinct differences among the isolates in their prevalence and severity on the barley varieties and thus these isolates are distinct races.     

共头霉的单孢孢子囊变种

我们从江苏、浙江两省采到的一些样品中分离得到六株毛霉菌种并鉴定为分别属于三个变种的同一个新种,即单孢共头霉原变种(Syncephalastrum monosporum Zheng et al.sp. nov. var. monosporum),单孢共头霉冠囊变种(Syncephalastrum monosporum Zheng et al. var. cristatum Zheng et al. var. nov.),以及单孢共头霉多重生变种(Syncephalastrum monosporum Zheng et al. var. pluriproliferum Zheng et al. var. nov.).它们与共头霉属的唯一已知种总状共头霉(Syncephalastrum racemosum Cohn ex Schroeter)的主要区别在于全部孢子囊都是单孢的小型孢子囊(柱孢囊)而不是像后者一样孢子成单行排列的多袍柱孢囊.我们把这些菌归人共头霉属而没有为它们专门成立一个新属的理由除因它们与总状共头霉有明显的亲缘关系外,主要还因我们认为在不具备其它重要区别特征的情况下,在毛霉目的分类中,无论在科级或属级的水平上,都不应过分强调单孢孢子囊的作用.尽管单孢共头霉是毛霉目内唯一具单孢子柱孢囊的种,我们仍然把它们归入共头霉属内.至于我们为什么要把这六株菌鉴定为一个种的三个变种而不是三个各自独立的种,则是由于我们承认共头霉属的唯一已知种总状共头霉是一个变异性很大的种而并没有把它分成许多不同的种,因此,我们对这个属的另外一个种,即单孢共头霉同样采用较大的种概念.     

Spore Dimorphism in a Microsporidan Isolate*

A microsporidan isolate currently considered to represent a mixed infection of Nosema necatrix Kramer, 1965 and Thelohania diazoma Kramer, 1965 was subjected to cultivation in hosts held at various temperatures. The ratio of the Nosema (monospore) to the Thelohania (octospore) forms at these temperatures was found to vary from 1:1 at 16 C to 1:0 at 32 C. Isolation technics using mechanical, temperature and temporal methods separated monosporous from octosporous forms for inoculation purposes. However, microscopic examination of hosts receiving these inocula revealed the presence of both monospores and octospores. Electrophoretic analysis of monospores and monospore-octospore mixtures indicated equivalent hydrophobic protein spectra. These observations suggest that this isolate has the ability to produce either single spores or spores in groups of eight. This microsporidan was not considered a member of the genus Stempellia since spores in groups of 2 or 4 were not observed. Retention of the name Nosema necatrix Kramer is suggested.     

Molecular phylogenetic and morphological analyses of Oidium heveae, a powdery mildew of rubber tree

Powdery mildew of rubber tree caused by Oidium heveae is an important disease of rubber plantations worldwide. Identification and classification of this fungus is still uncertain because there is no authoritative report of its morphology and no record of its teleomorphic stage. In this study, we compared five specimens of the rubber powdery mildew fungus collected in Malaysia, Thailand, and Brazil based on morphological and molecular characteristics. Morphological results showed that the fungus on rubber tree belongs to Oidium subgen. Pseudoidium. Nucleotide sequence analysis of the ribosomal DNA internal transcribed spacer (ITS) region and the large subunit rRNA gene (28S rDNA) were conducted to determine the relationships of the rubber powdery mildew fungus and to link this anamorphic fungus with its allied teleomorph. The results showed that the rDNA sequences of the two specimens from Malaysia were identical to a specimen from Thailand, whereas they differed by three bases from the two Brazilian isolates: one nucleotide position in the ITS2 and two positions in the 28S sequences. The ITS sequences of the two Brazilian isolates were identical to sequences of Erysiphe sp. on Quercus phillyraeoides collected in Japan, although the 28S sequences differed at one base from sequences of this fungus. Phylogenetic trees of both rDNA regions constructed by the distance and parsimony methods showed that the rubber powdery mildew fungus grouped with Erysiphe sp. on Q. phillyraeoides with 100% bootstrap support. Comparisons of the anamorph of two isolates of Erysiphe sp. from Q. phillyraeoides with the rubber mildew did not reveal any obvious differences between the two powdery mildew taxa, which suggests that O. heveae may be an anamorph of Erysiphe sp. on Q. phillyraeoides. Cross-inoculation tests are required to substantiate this conclusion.     

Fungus gardens of the leafcutter ant Atta colombica function as egg nurseries for the snake Leptodeira annulata

Attine ants are well known for their mutualistic symbiosis with fungus gardens, but many other symbionts and commensals have been described. Here, we report the discovery of two clusters of large snake eggs in neighboring fungus gardens of a mature Atta colombica colony. The eggs were completely embedded within the fungus garden and were ignored by the host ants, even when we placed them into another, freshly excavated fungus garden of the same colony. All five eggs contained embryos and two snakes eventually hatched, which we identified as being banded cat eyed snakes Leptodeira annulata L. Ant fungus gardens are likely to provide ideal climatic conditions for developing snake eggs and almost complete protection from egg predation. Our observations therefore indicate that mature banded cat eyed snakes are able to enter and oviposit in large and well defended Atta colonies without being attacked by ant soldiers and that also newly hatched snakes manage to avoid ant attacks when they leaving their host colony. We speculate that L. annulata might use Atta and Acromyrmex leafcutter ant colonies as egg nurseries by some form of chemical insignificance, but more work is needed to understand the details of this interaction. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Isolation of a homothallic mutant in <Emphasis Type="Italic">Lentinula edodes</Emphasis>

To obtain a homothallic mutant in Lentinula edodes, basidiospores derived from the common Bmut dikaryon (A1B1mut × A2B1mut) were treated with UV irradiation. Of a total of approximately 5000 monosporous cultures recovered, a single basidiospore isolate was found to produce the hyphae bearing clamp connections without mating. This mutant strain could form fruit bodies, and all its single basidiospore isolates developed into colonies with clamp connections. Such homothallic behaviors were transmitted from the mutant strain to the next generation. During the germination and following hyphal elongation in a single basidiospore of mutant strain, clamp connections were clearly detected in multicellular hyphae, which contained two nuclei in each cell. Their clamp connections were morphologically variable, viz., pseudo, abnormal, and true clamps. Amplified fragment length polymorphism (AFLP) profiles among the basidiospore isolates of mutant strain were identical, indicating that the mutant strain produced isogenic basidiospore progeny. Contribution no. 385 from the Tottori Mycological Institute     

Microsatellite primers for fungus‐growing ants

We isolated five polymorphic microsatellite loci from a library of two thousand recombinant clones of two fungus‐growing ant species, Cyphomyrmex longiscapus and Trachymyrmex cf. zeteki. Amplification and heterozygosity were tested in five species of higher attine ants using both the newly developed primers and earlier published primers that were developed for fungus‐growing ants. A total of 20 variable microsatellite loci, developed for six different species of fungus‐growing ants, are now available for studying the population genetics and colony kin‐structure of these ants.     

Digestive capacities of leaf-cutting ants and the contribution of their fungal cultivar to the degradation of plant material

Leaf-cutting ants (tribe Attini) are a unique group of ants that cultivate a fungus that serves as a main source of their food. The fungus is grown on fresh leaves that are harvested by workers. We examine the respective contribution of ants and their symbiotic fungus in the degradation of plant material by examining the digestive capacities of seven Attini species in the genera Atta and Acromyrmex. The results show that both, the ants and their mutualistic fungi, have complementary enzymatic activities. Ants are specialized in the degradation of low molecular weight substrates (oligosaccharides and heterosides) whereas the fungus displays high polysaccharidase activity. The two genera Atta and Acromyrmex are not distinguished by a specific enzymatic activity. The seven different mutualistic associations examined display a similar enzymatic profile but have quantitative differences in substrate degradation activities. The respective contribution of ants and the fungus garden in plant degradation are discussed.     

稻瘟病菌株的DNA指纹分析及小种鉴别

基于对稻瘟病菌(Pyricularia oryzae)基因文库的分析,我们找到了一套含重复顺序的克隆。其中POR6和POR7被证实具有高度的多态性并随机散布于稻瘟病菌生理小种的致病性时,可以获得可分辨的基因组特异的杂交带型。我们还分析了致病性与8个稻瘟病菌株DNA指纹图谱之间的关系,结果表明各个小种组合间的百分相似率S_xy,值与该小种组合间共同侵染的鉴别品种数目有正相关性。     

Comparison of gut-associated and nest-associated microbial communities of a fungus-growing termite (Odontotermes yunnanensis)

Abstract The digestion of cellulose by fungus-growing termites involves a complex of different organisms, such as the termites themselves, fungi and bacteria. To further investigate the symbiotic relationships of fungus-growing termites, the microbial communities of the termite gut and fungus combs of Odontotermes yunnanensis were examined. The major fungus species was identified as Termitomyces sp. To compare the micro-organism diversity between the digestive tract of termites and fungus combs, four polymerase chain reaction clone libraries were created (two fungus-targeted internal transcribed spacer [ITS]– ribosomal DNA [rDNA] libraries and two bacteria-targeted 16S rDNA libraries), and one library of each type was produced for the host termite gut and the symbiotic fungus comb. Results of the fungal clone libraries revealed that only Termitomyces sp. was detected on the fungus comb; no non-Termitomyces fungi were detected. Meanwhile, the same fungus was also found in the termite gut. The bacterial clone libraries showed higher numbers and greater diversity of bacteria in the termite gut than in the fungus comb. Both bacterial clone libraries from the insect gut included Firmicutes, Bacteroidetes, Proteobacteria, Spirochaetes, Nitrospira, Deferribacteres, and Fibrobacteres, whereas the bacterial clone libraries from the fungal comb only contained Firmicutes, Bacteroidetes, Proteobacteria, and Acidobacteris.     

Davisia hexagrammi n. sp. (Myxosporea: Sinuolineidae) parasitic in the urinary bladder of marine fishes from the coasts of the Yellow Sea and Bohai Bay,China

A new species of myxosporean (Sinuolineidae), Davisia hexagrammi n. sp. from marine fishes collected from the coasts off Qingdao (Tsingtao) and Rongcheng on the Yellow Sea coast and Laizhou Bay, China, is described. Both spores and plasmodia were found in the urinary bladder of two hosts, Hexagrammos otakii Jordan & Starks and Agrammus agrammus (Temminck & Schlegel). The diagnostic features of D. hexagrammi n. sp. are: trophozoite monosporous or disporous; spore body spherical, 9.5-10.5 (9.9±0.5)× 10-12 (10.8±1.0) m in size and with a straight or slightly sinuous sutural line; two shell valves each with one long, hollow lateral appendage of 44-59 (52.4±6.9) m in length; two spherical polar capsules arranged anteriorly, well-separated from each other and 3.5-4 (3.8±0.2) m in diameter, coelozic; marine habitat.     

Nachweis signifikant verschiedener Pilzpopulationen bei gleicher Bodennutzung

Summary The soil fungus flora in two crop-rotation experiments was studied using the soil-washing technique. Numerous analyses were carried out at regular intervals during three years.Data of abundance and frequence are tabulated for the 91 most common species. Although these figures showed a significant correlation (r=0.790 for 91 species) between the two fungus floras, significant differences were found in the abundance of 37 species (atP=0.01). It is concluded, that there are still considerable differences in similar soils under the same plant cover. Even stronger differences were found, when four Dutch polder soils were included in the comparison.It is suggested, that these differences reflect the different previous cultivations rather than the influence of physical or chemical soil factors.     

Fungi associated with cellulose decomposition in the tidal mud-flats of Kuwait

Fungi potentially able to decompose cellulose, in the tidal mud-flats of Kuwait, have been investigated. More than 58 species were isolated and their cellulytic ability were tested. Many of the species recorded are well known cellulose decomposers, while for many others the strong cellulytic activity is a new record e.g. Arachniotus dankaliensis, Lasiobolidium orbiculoides, Corynascus sepedonium, and Pesotum sp. Comparison of the frequency of occurrence and cellulytic ability, in all species reported, revealed that there is no coincidence between the two parameters. The high frequency of any fungus does not imply that this fungus is an active cellulose decomposer in the soil and similarly low frequency fungi are not necessarily weak decomposers. It is likely possible, that the competitive saprophytic ability of the fungus which determine its role in the process of cellulose decomposition in the soil rather than its cellulytic ability in pure culture.     

Two allelic genes responsible for vegetative incompatibility in the fungus Podospora anserina are not essential for cell viability

Summary Vegetative incompatibility is a lethal reaction that destroys the heterokaryotic cells formed by the fusion of hyphae of non-isogenic strains in many fungi. That incompatibility is genetically determined is well known but the function of the genes triggering this rapid cell death is not. The two allelic incompatibility genes, s and S, of the fungus Podospora anserina were characterized. Both encode 30 kDa polypeptides, which differ by 14 amino acids between the two genes. These two proteins are responsible for the incompatibility reaction that results when cells containing s and S genes fuse. Inactivation of the s or S gene by disruption suppresses incompatibility but does not affect the growth or the sexual cycle of the mutant strains. This suggests that these incompatibility genes have no essential function in the life cycle of the fungus.     

Westerdykella globosa,a proposal for a new combination

The surface ornamentation of ascospores ofPreussia globosa was compared in an isolate from paddy soil in Japan and a culture derived from the holotype. The ascospores of two cultures were characterized by the surface ornamentation of a single, semicircular spiral ridge. This new finding strongly suggested that the fungus should be transferred to the genusWesterdykella. Therefore, the morphological and cultural characters of the fungus were re-examined, and the new combinationWesterdykella globosa is herein proposed.