Glucofructosan biosynthesis in Fusarium oxysporum

Low MW glucofructosans have been detected in the medium of Fusarium oxysporum. A 53-fold purification of fructosyl transferase has been achieved by ethanol precipitation, DEAE-cellulose and Sephadex G-100 column chromatography. Maximum fructosyl transferase activity coincided with maximum glucofructosan concentration in the medium. Invertase showed greatest activity in the later stages of growth when glucofructosans were absent. Fructosyl transferase and invertase have been separated by DEAE-cellulose column chromatography. On the basis of kinetic studies and effect of nucleotides on fructosyl transferase in the presence and absence of MgCl₂, a two site active centre linked through a nucleotide bridge is proposed. Fructosyl transferase and invertase are highly phosphorylated.     

A multilocus sequence analysis of the genus Xanthomonas

A multilocus sequence analysis (MLSA) of strains representing all validly published Xanthomonas spp. (119 strains) was conducted using four genes; dnaK, fyuA, gyrB and rpoD, a total of 440 sequences. Xanthomonas spp. were divided into two groups similar to those indicated in earlier 16S rDNA comparative analyses, and they possibly represent distinct genera. The analysis clearly differentiated most species that have been established by DNA-DNA reassociation. A similarity matrix of the data indicated clear numerical differences that could form the basis for species differentiation in the future, as an alternative to DNA-DNA reassociation. Some species, X. cynarae, X. gardneri and X. hortorum, formed a single heterogeneous group that is in need of further investigation. X. gardneri appeared to be a synonym of X. cynarae. Recently proposed new species, X. alfalfae, X. citri, X. euvesicatoria, X. fuscans and X. perforans, were not clearly differentiated as species from X. axonopodis, and X. euvesicatoria and X. perforans are very probably synonyms. MLSA offers a powerful tool for further investigation of the classification of Xanthomonas. Based on the dataset produced, the method also offers a relatively simple way of identifying strains as members of known species, or of indicating their status as members of new species.     

Morphology,zoospore ultrastructure,and phylogenetic position of Polyphlyctis willoughbyi, a new species in Chytridiales (Chytridiomycota)

The purpose of our research is to investigate the morphology, zoospore ultrastructure, and molecular phylogenetic placement of a chytrid from Australia. From a survey of chytrid fungi in New South Wales, Australia, we isolated strain PL AUS 026 and putatively identified it as Polyphlyctis unispina. Light microscopic evaluation determined strain PL AUS 026 to be similar to two other strains of P. unispina characterized in the literature but to have a more complex thallus than that of the type. Molecular phylogenetic analyses placed our strain as sister of or basal to Chytridiaceae, Chytridiales. Ultrastructural analysis of the zoospore of strain PL AUS 026 revealed unique features. On the basis of our analyses we designate strain PL AUS 026 as a new species, Polyphlyctis willoughbyi. This research extends our concept of Chytridiaceae systematics and ultrastructural variation in the Chytridiales zoospore.     

A phylogenetic and morphological overview of sections Bohusia, Sanguinolenti, and allied sections within Agaricus subg. Pseudochitonia with three new species from France,Iran, and Portugal

The genus Agaricus was recently rearranged to accommodate numerous tropical taxa. Accordingly, the genus was split into six subgenera and 22 sections of which 12 are included in A. subg. Pseudochitonia. Preliminary data indicated that three putative new species belong to this subgenus. Our objectives were to describe these species, to determine to which sections they belong, and to experience the interest of some traditional traits in this new context. We morphologically described Agaricus coniferarum from France and Portugal, Agaricus iranicus from Iran, and Agaricus lusitanicus from Portugal. Multi-gene phylogenetic analyses based on ITS, LSU, and tef1 sequence data of representatives of the 12 sections clearly indicated that A. coniferarum and A. lusitanicus are placed in Agaricus sect. Bohusia, while A. iranicus is in A. sect. Sanguinolenti. Incidentally, we replaced the illegitimate name Agaricus magnivelaris by Agaricus fiardianus. In a phylogenetic tree, based on all available ITS sequence data and focussing on six related sections, we examined the phylogenetic distribution of various characters. The intensity of red discolouration when the sporocarp is rubbed or cut appeared as a phylogenetically weak informative trait. We propose a determination key leading to a group of three hardly distinguishable sections (Bohusia, Nigrobrunnescentes, and Sanguinolenti).     

Description of Scutovertex pileatus sp. nov. (Acari, Oribatida, Scutoverticidae) and molecular phylogenetic investigation of congeneric species in Austria

The oribatid mite Scutovertex pileatus sp. nov. is described on the basis of adult individuals originating from southern Austria (Carinthia). The new species shows the typical habitus of Scutovertex and is distinguished by the cerotegument and cuticle forming irregular nodules and bars over the entire body; the rostrum with two visor-like projections, with the ventral projection larger and arched ventrally; short lamellar setae; two pairs of converging ridges between the lamellae; small notogastral setae that are not broadened distally; and a sclerotized rib across the mentum. Furthermore, DNA sequences of the COI gene (region 2, 567 bp) of S. pileatus were compared with those of S. minutus, S. sculptus, using Cymbaeremaeus cymba as the outgroup. Molecular data unambiguously support the discreteness of all three species by placing them reciprocally monophyletic, as well as by large genetic divergences. Interspecific distances among C. cymba, S. minutus, S. pileatus and S. sculptus amounted to 13.7-29.9%.     

Taxonomic and phylogenetic analysis of the Oomycota mosquito larvae pathogen Crypticola clavulifera

Beside the taxonomic features displayed by Crypticola clavulifera in culture and unpublished data on its phylogeny, little is known about the main phylogenetic features of this unusual mosquito pathogen. We have PCR amplified the 18S SSU rDNA, ITS, and the partial coding regions of COXII and COXI to study the phylogenetic features of this pathogen within the tree of life. Our phylogenetic data showed C. clavulifera clustered among homologous DNA sequences of the Oomycota class Saprolegniomycetes. Our study support previous taxonomic and unpublished molecular analysis, placing this unusual mosquito larvae pathogen as part of the earliest diverging cluster within the Saprolegniomycetes.     

A review of the subgenus Epicterodes of Arichanna (Lepidoptera,Geometridae, Ennominae), with description of one new species

The subgenus Epicterodes Wehrli, 1933 of Arichanna Moore, 1868 is reviewed. Six species are recognized, of which, A. (E). denticularia sp. nov. is described as new to science from China. One new synonym is established based on morphological and genetic similarity: A. (E.) flavomacularia Leech, 1897 (=A. (E.) perimelaina Wehrli, 1933 syn. nov.). Results of DNA barcoding for Epicterodes are briefly discussed. Diagnoses for all the species are provided and illustrations of adults, genitalia and distribution map are presented.     

Glucofructosan biosynthesis in Fusarium oxysporum: Regulation and substrate specificity of fructosyl transferase and invertase

Mycelium of Fusarium oxysporum grown on a glucose-containing medium lacked fructosyl transferase and invertase activities. Synthesis of fructosyl t     

Systemic acquired resistance in Cavendish banana induced by infection with an incompatible strain of Fusarium oxysporum f. sp. cubense

Fusarium wilt of banana is caused by the soil-borne fungus Fusarium oxysporum f. sp. cubense (Foc). The fact that there are no economically viable biological, chemical, or cultural measures of controlling the disease in an infected field leads to search for alternative strategies involving activation of the plant's innate defense system. The mechanisms underlying systemic acquired resistance (SAR) are much less understood in monocots than in dicots. Since systemic protection of plants by attenuated or avirulent pathogens is a typical SAR response, the establishment of a biologically induced SAR model in banana is helpful to investigate the mechanism of SAR to Fusarium wilt. This paper described one such model using incompatible Foc race 1 to induce resistance against Foc tropical race 4 in an in vitro pathosystem. Consistent with the observation that the SAR provided the highest level of protection when the time interval between primary infection and challenge inoculation was 10 d, the activities of defense-related enzymes such as phenylalanine ammonia lyase (PAL, EC 4.3.1.5), peroxidase (POD, EC 1.11.1.7), polyphenol oxidase (PPO, EC 1.14.18.1), and superoxide dismutase (SOD, EC 1.15.1.1) in systemic tissues also reached the maximum level and were 2.00–2.43 times higher than that of the corresponding controls on the tenth day. The total salicylic acid (SA) content in roots of banana plantlets increased from about 1 to more than 5 μg g⁻¹ FW after the second leaf being inoculated with Foc race 1. The systemic up-regulation of MaNPR1A and MaNPR1B was followed by the second up-regulation of PR-1 and PR-3. Although SA and jasmonic acid (JA)/ethylene (ET) signaling are mostly antagonistic, systemic expression of PR genes regulated by different signaling pathways were simultaneously up-regulated after primary infection, indicating that both pathways are involved in the activation of the SAR.     

The Paxillus involutus (Boletales, Paxillaceae) complex in Europe: Genetic diversity and morphological description of the new species Paxillus cuprinus, typification of P. involutus s.s., and synthesis of species boundaries

Paxillus involutus is a model species for ecological or physiological studies of ectomycorrhizal agaricomycetes. Three to six groups or species linked to it have been ecologically and morphologically distinguished. Phylogenetic studies have revealed the existence of four species in Europe: Paxillus ammoniavirescens, Paxillus obscurisporus, P. involutus, and a fourth as yet not described species. We studied 47 collections from 24 French and Italian locations, supplemented with GenBank data, in order to genetically and taxonomically delineate these species. Phylogenetic analyses of three nuclear DNA regions (rDNA internal transcribed spacer (ITS), tef1-α, and gpd) confirmed the four European species. Morphology, culture, and ecology features allowed us to delineate species boundaries and to describe the fourth species we named Paxillus cuprinus since it turns coppery with age. As there is no existing original herbarium specimen for P. involutus, one of our collections was chosen as the epitype. The low genetic diversity found in P. cuprinus correlates with stable morphological traits (basidiome colour, ovoid–amygdaliform spores with an apical constriction) and with ecological preferences (association with Betulaceae in open and temperate areas). In contrast, P. ammoniavirescens is characterized by a high genetic diversity and a high variation of its morphological and ecological features.     

Species delimitation in the European species of Clavulina (Cantharellales, Basidiomycota) inferred from phylogenetic analyses of ITS region and morphological data

The identification of the conventionally accepted species of Clavulina (Cantharellales, Basidiomycota) in Europe (Clavulina amethystina, Clavulina cinerea, Clavulina cristata, and Clavulina rugosa) is often difficult and many specimens are not straightforwardly assignable to any of those four species, which is why some authors have questioned their identity. In order to assess the status of those species, a morphological examination was combined with the molecular analysis of the ITS region. The same six major clades were obtained in the Bayesian and parsimony phylogenetic analyses, and all six clades were well-supported at least by one of the analyses. Morphological characters, such as the overall branching pattern, the presence and intensity of grey colour, the cristation of the apices, and basidiospore size and shape were to various extents correlated with the phylogenetic signal obtained from the ITS region. The congruence between the molecular analyses and morphology, rather than geographical origin, suggests the existence of several species that can be delimited using a combined phylogenetic and morphological species recognition. The analyses revealed that C. cristata and C. rugosa are well-delimited species. In contrast, more than one taxa could be subsumed under the names C. amethystina and C. cinerea, the taxonomical complexity of which is discussed. The ITS region is proved to be adequate to separate phylogenetic species of Clavulina.     

There it is! Fusarium pseudograminearum did not lose the fusaristatin gene cluster after all

Fusarium pseudograminearum is a significant pathogen of cereals in arid regions worldwide and has the ability to produce numerous bioactive secondary metabolites. The genome sequences of seven F. pseudograminearum strains have been published and in one of these strains, C5834, we identified an intact gene cluster responsible for biosynthesis of the cyclic lipopeptide fusaristatin A. The high level of sequence identity of the fusaristatin cluster remnant in strains that do not produce fusaristatin suggests that the absence of the cluster evolved once, and subsequently the resulting locus with the cluster fragments became widely dispersed among strains of F. pseudograminearum in Australia. We examined a selection of 99 Australian F. pseudograminearum isolates to determine how widespread the ability to produce fusaristatin A is in F. pseudograminearum. We identified 15 fusaristatin producing strains, all originating from Western Australia. Phylogenetic analyses could not support a division of F. pseudograminearum into fusaristatin producing and nonproducing populations, which could indicate the loss has occurred relatively recent.     

内生真菌角担子菌B6对连作西瓜土壤尖孢镰刀菌的影响

建立了快速定量检测土壤中角担子菌(Ceratobasidum stevensii)B6的实时定量PCR方法,同时跟踪了土壤中尖孢镰刀菌数量的动态变化,以及不同的发酵组分对开花期西瓜土壤微生物区系的影响。PCR扩增分析表明引物Cf1/Cr1有很好的特异性,能对角担子菌B6特异性扩增得到371bp的条带,对其它10株真菌不能有效扩增。使用荧光定量PCR对施加角担子菌B6的土壤总DNA扩增,结果表明将活菌B6固体发酵物施加到土壤1周后,B6的数量有一定的增殖,达到7.4 log(pg DNA/g干土),随着时间推移,数量逐渐减少,在第5周的时候低于检测限;而液体发酵液处理从一开始施加到土壤后,B6的数量就开始逐渐减少,在第4周的时候就低于检测限。施加活的B6菌4周内能够有效地控制尖孢镰刀菌的数量(尖孢镰刀菌数量维持在5×103 CFU/g干土左右),之后随着B6数量的减少尖孢镰刀菌数量大量增加。活菌B6在土壤中能够存活1个月左右,不会过度影响土著微生物区系,是一株环境友好型菌株,对土壤微环境的干扰较小。     

Robust Frankia phylogeny,species delineation and intraspecies diversity based on Multi-Locus Sequence Analysis (MLSA) and Single-Locus Strain Typing (SLST) adapted to a large sample size

Diazotrophic Actinobacteria of the genus Frankia represent a challenge to classical bacterial taxonomy as they include many unculturable strains. As a consequence, we still have a poor understanding of their diversity, evolution and biogeography. In this study, a Multi-Locus Sequence Analysis (MLSA) using atpD, dnaA, ftsZ, pgk, and rpoB loci was done on a large set of cultured and uncultured strains, compared to 16S rRNA and correlated to Average Nucleotide Identity (ANI) from available Frankia genomes. MLSA provided a robust resolution of Frankia genus phylogeny and clarified the status of unresolved species and complex of species.The robustness of single-gene topologies and their congruence with the MLSA tree were tested. Lateral Gene Transfers (LGT) were few and scattered, suggesting they had no impact on the concatenate topology. The pgk marker – providing the longest sequence, highest mean genetic divergence and least occurrence of LGT – was used to survey an unequalled number of Alnus-infective Frankia — mainly uncultured strains from a broad range of host-species and geographic origins. This marker allowed reliable Single-Locus Strain Typing (SLST) below the species level, revealed an undiscovered taxonomical diversity, and highlighted the effect of cultivation, sporulation phenotype and host plant species on symbiont richness, diversity and phylogeny.     

Morphological and molecular concordance for the recognition of two species in the New ZealandPolystichum richardii (Hook.) J. Smith complex

The New Zealand fernPolystichum richardii is shown to comprise at least two evolutionary lineages. A narrow-scaled morphological form and a wide-scaled morphological form are recognised. Principal Component Analysis of a set of frond, soral and spore characters supports this morphological separation. Amplified Fragment Length Polymorphism (AFLP) DNA fingerprinting shows that the two morphological forms are also genetically distinct. They are sympatric across a broad area of central New Zealand, and often grow together without apparent ecological separation at the local level. Both are known to form sterile hybrids withP. vestitum, suggesting that both morphological forms ofP. richardii are at least partially outcrossing. The morphological and genetic distinctiveness of these two morphological forms, combined with their sympatric distributions and their (at least partially) outcrossing mating systems, merits their recognition as separate species.     

Four new Ophiostoma species associated with hardwood-infesting bark beetles in Norway and Poland

Ophiostoma spp. (Ophiostomatales, Ascomycota) are well-known fungi associated with bark and ambrosia beetles (Curculionidae: Scolytinae, Platypodinae). Fungi in the Ophiostomatales include serious tree pathogens as well as agents of timber blue-stain. Although these fungi have been extensively studied in the northern hemisphere, very little is known regarding their occurrence on hardwoods in Europe. The aims of the present study were to identify and characterize new Ophiostoma spp. associated with bark and ambrosia beetles infesting hardwoods in Norway and Poland, and to resolve phylogenetic relationships of Ophiostoma spp. related to the Norwegian and Polish isolates, using multigene phylogenetic analyses. Results obtained from five gene regions (ITS, LSU, β-tubulin, calmodulin, translation elongation factor 1-α) revealed four new Ophiostoma spp. These include Ophiostoma hylesinum sp. nov., O. signatum sp. nov., and O. villosum sp. nov. that phylogenetically are positioned within the Ophiostoma ulmi complex. The other new species, Ophiostoma pseudokarelicum sp. nov. reside along with Ophiostoma karelicum in a discrete, well-supported phylogenetic group in Ophiostoma s. stricto. The results of this study clearly show that the diversity and ecology of Ophiostoma spp. on hardwoods in Europe is poorly understood and that further studies are required to enrich our knowledge about these fungi.     

Changes in DNA composition in the evolution of Vicia species

Summary The composition of nuclear DNA in 3 Vicia species are compared. The species V. eriocarpa, V. johannis and V. melanops are from three separate subgeneric sections of Vicia and show a fourfold variation in their amounts of nuclear DNA. DNA melting experiments, buoyant density gradient analysis and Cot reassociation experiments show that the quantitiative change in nuclear DNA between the three species is achieved by changes in the amounts of both repetitive and nonrepetitive DNA sequences. It is suggested that while the increase in the repetitive fraction is achieved by the proliferation of repetitive base sequences the increase in the nonrepetitive fraction is due to the steady accretion of highly diverged base sequences resulting from mutations, deletions, insertions and base sequence rearrangements among families of repetitive sequences.