A practical approach for identifications based on mycotoxin characters of Penicillium

The taxonomy of the penicillia is unstable particularly in the important antibiotic and mycotoxin-producing subgenus Penicillium. There are difficulties relating identifications to mycotoxin production. Also, the validity of dual nomenclature for pleomorphic fungi is under discussion increasingly. Patulin is an important mycotoxin produced by various fungi and has strict limits in the European Union. The mycotoxin and/or the isoepoxydon dehydrogenase (IDH) gene of the metabolic pathway have been assessed in 318 strains predominately of subgenus Penicillium. These data were used to classify the isolates. Subgenus Penicillium contained most of the IDH and patulin positives. The species and varieties in subgenus Penicillium which were associated with patulin detection can be reduced to one name, viz. Penicillium Pen p+ (p = patulin). This has been extended to other mycotoxin producing penicillia to indicate the scope of the scheme. The classification will lead to the number of taxa being reduced, while avoiding species names and hence dual nomenclature. Culture independent analysis of environmental samples is mentioned. The scheme could be used with advantage for other fungi.     

中国农业植物病原菌物常见种属名录

植物病原菌物是造成植物病害的主要病原物,可对生态安全、粮食安全、生物多样性造成重要威胁和灾害.近年来,菌物分类学的研究逐步深入,大量新分类单元被描述、高阶分类系统被修订和完善.在墨尔本和深圳两届国际植物学大会上,对《国际藻类、菌物和植物命名法规》中涉及菌物的部分做出了重大调整以实现"一菌一名".上述研究进展和改变对植物...     

Ericaceous plant–fungus network in a harsh alpine–subalpine environment

In terrestrial ecosystems, plant species and diverse root‐associated fungi form complex networks of host–symbiont associations. Recent studies have revealed that structures of those below‐ground plant–fungus networks differ between arbuscular mycorrhizal and ectomycorrhizal symbioses. Nonetheless, we still remain ignorant of how ericaceous plant species, which dominate arctic and alpine tundra, constitute networks with their root‐associated fungi. Based on a high‐throughput DNA sequencing data set, we characterized the statistical properties of a network involving 16 ericaceous plant species and more than 500 fungal taxa in the alpine–subalpine region of Mt. Tateyama, central Japan. While all the 16 ericaceous species were associated mainly with fungi in the order Helotiales, they varied remarkably in association with fungi in other orders such as Sebacinales, Atheliales, Agaricales, Russulales and Thelephorales. The ericaceous plant–fungus network was characterized by high symbiont/host preferences. Moreover, the network had a characteristic structure called ‘anti‐nestedness’, which has been previously reported in ectomycorrhizal plant–fungus networks. The results lead to the hypothesis that ericaceous plants in harsh environments can host unexpectedly diverse root‐associated fungal taxa, constituting networks whose structures are similar to those of previously reported ectomycorrhizal networks but not to those of arbuscular mycorrhizal ones.     

Effect of chitosan on hyphal growth and spore germination of plant pathogenic and biocontrol fungi

Aims: To investigate the toxic effect of chitosan on important root pathogenic and biocontrol fungi (nematophagous, entomopathogenic and mycoparasitic). Methods and Results: We have used standard bioassays to investigate the effect of chitosan on colony growth and developed bioassays to test spore germination. The results showed that the root pathogenic and mycoparasitic fungi tested were more sensitive to chitosan than nematophagous and entomopathogenic fungi. Chitosanases (and perhaps related enzymes) are involved in the resistance to chitosan. Two fungi, one sensitive to chitosan, Fusarium oxysporum f. sp. radicis‐lycopersici, and one less sensitive, Pochonia chlamydosporia, were selected for ultrastructural investigations. Transmission electron microscopy revealed differences in the ultrastructural alterations caused by chitosan in the spores of the plant pathogenic fungus and in those of the nematophagous fungus. Confocal laser microscopy showed that Rhodamine‐labelled chitosan enters rapidly into conidia of both fungi, in an energy‐dependent process. Conclusions: Nematophagous and entomopathogenic fungi are rather resistant to the toxic effect of chitosan. Resistance of nematophagous and entomopathogenic fungi to chitosan could be associated with their high extracellular chitosanolytic activity. Furthermore, ultrastructural damage is much more severe in the chitosan sensitive fungus. Significance and impact of the study: The results of this paper suggest that biocontrol fungi tested could be combined with chitosan for biological control of plant pathogens and pests.     

Specific amplification of 18S fungal ribosomal genes from vesicular-arbuscular endomycorrhizal fungi colonizing roots.

The first DNA sequences obtained from arbuscular endomycorrhizal fungi are reported. They were obtained by directly sequencing overlapping amplified fragments of the nuclear genes coding for the small subunit rRNA. These sequences were used to develop a polymerase chain reaction primer (VANS1) that enables the specific amplification of a portion of the vesicular-arbuscular endomycorrhizal fungus small subunit rRNA directly from a mixture of plant and fungal tissues. The specificity of this primer for arbuscular endomycorrhizal fungi was demonstrated by testing it on a number of organisms and by sequencing the fragment amplified from colonized leek (Allium porum) roots. This approach, coupled with other molecular techniques, will facilitate rapid detection, identification, and possibly quantitation of arbuscular endomycorrhizal fungi.     

Specific interactions between arbuscular mycorrhizal fungi and plant growth-promoting bacteria: as revealed by different combinations

The interactions between two plant growth-promoting rhizobacteria (PGPR, Pseudomonas fluorescens SBW25 and Paenibacillus brasilensis PB177), two arbuscular mycorrhizal (AM) fungi (Glomus mosseae and Glomus intraradices) and one pathogenic fungus (Microdochium nivale) were investigated on winter wheat (Triticum aestivum cultivar Tarso) in a greenhouse trial. PB177, but not SBW25, had strong inhibitory effects on M. nivale in dual culture plate assays. The results from the greenhouse experiment show very specific interactions; for example, the two AM fungi react differently when interacting with the same bacteria on plants. Glomus intraradices (single inoculation or together with SBW25) increased plant dry weight on M. nivale-infested plants, suggesting that the pathogenic fungus is counteracted by G. intraradices, but PB177 inhibited this positive effect. This is an example of two completely different reactions between the same AM fungus and two species of bacteria, previously known to enhance plant growth and inhibit pathogens. When searching for plant growth-promoting microorganisms, it is therefore important to test for the most suitable combination of plant, bacteria and fungi in order to achieve satisfactory plant growth benefits.     

Specific amplification of 18S fungal ribosomal genes from vesicular-arbuscular endomycorrhizal fungi colonizing roots.

The first DNA sequences obtained from arbuscular endomycorrhizal fungi are reported. They were obtained by directly sequencing overlapping amplified fragments of the nuclear genes coding for the small subunit rRNA. These sequences were used to develop a polymerase chain reaction primer (VANS1) that enables the specific amplification of a portion of the vesicular-arbuscular endomycorrhizal fungus small subunit rRNA directly from a mixture of plant and fungal tissues. The specificity of this primer for arbuscular endomycorrhizal fungi was demonstrated by testing it on a number of organisms and by sequencing the fragment amplified from colonized leek (Allium porum) roots. This approach, coupled with other molecular techniques, will facilitate rapid detection, identification, and possibly quantitation of arbuscular endomycorrhizal fungi.     

Phylogenetic congruence between subtropical trees and their associated fungi

Recent studies have detected phylogenetic signals in pathogen–host networks for both soil‐borne and leaf‐infecting fungi, suggesting that pathogenic fungi may track or coevolve with their preferred hosts. However, a phylogenetically concordant relationship between multiple hosts and multiple fungi in has rarely been investigated. Using next‐generation high‐throughput DNA sequencing techniques, we analyzed fungal taxa associated with diseased leaves, rotten seeds, and infected seedlings of subtropical trees. We compared the topologies of the phylogenetic trees of the soil and foliar fungi based on the internal transcribed spacer (ITS) region with the phylogeny of host tree species based on matK, rbcL, atpB, and 5.8S genes. We identified 37 foliar and 103 soil pathogenic fungi belonging to the Ascomycota and Basidiomycota phyla and detected significantly nonrandom host–fungus combinations, which clustered on both the fungus phylogeny and the host phylogeny. The explicit evidence of congruent phylogenies between tree hosts and their potential fungal pathogens suggests either diffuse coevolution among the plant–fungal interaction networks or that the distribution of fungal species tracked spatially associated hosts with phylogenetically conserved traits and habitat preferences. Phylogenetic conservatism in plant–fungal interactions within a local community promotes host and parasite specificity, which is integral to the important role of fungi in promoting species coexistence and maintaining biodiversity of forest communities.     

Castles and cuitlacoche: the first international Ustilago conference

The first international Ustilago conference was held in Marburg, Germany from August 22 to 25, 2002. The meeting focused on molecular genetic and cell biology research with Ustilago maydis, the causative agent of common smut of maize. This fungus has emerged as a useful experimental organism for studying the biology of basidiomycete fungi, with a particular emphasis on the interaction of the fungus with the host plant. Thus presentations at the meeting covered the range of current research topics including DNA recombination and repair, mating and sexual development, phytopathology, cell biology, the cell cycle, signaling, and genomics. The meeting also highlighted historical aspects of U. maydis research with presentations by pioneers in the field including Robin Holiday (recombination), Yigal Koltin (killer phenomenon) and Peter Day (plant pathology).     

Pandora's mycological box: molecular sequences vs. morphology in understanding fungal relationships and biodiversity

Fundamental reappraisals of diverse traditional ideas in mycology have become necessary as a result of molecular insights. These different insights are discussed in relation to: the positions of microsporidia, slime moulds and oomycetes; the basal position of lichen fungi in the evolution of ascomycetes forming fruit bodies; remodelling of orders and families; changed generic concepts; the issue of whether permitting a dual nomenclature for the different states of pleomorphic fungi should be continued; and the recognition of additional cryptic species within a "species". The molecular data has necessitated a reassessment of the systematic importance of many types of characters. Also, the techniques open exciting horizons and undreamed of abilities through being able to identify non-sporing fungi in ecological samples and plant material, and revealing unexpected levels of diversity in hitherto little-explored habitats. Major advances in understanding how fungi operate through total genomic approaches can be anticipated as more are completely sequenced. The Pandora's box of molecular surprises is to be seen as one of blessings and not one of miseries and evils.     

Monotropa uniflora: morphological and molecular assessment of mycorrhizae retrieved from sites in the sub-boreal spruce biogeoclimatic zone in central British Columbia

Plant species in the subfamily Monotropoideae are achlorophyllous and have developed a complex mode of nutrition, receiving photosynthates from neighboring trees via shared fungi. To explore the mycorrhizal associations of Monotropa uniflora in central British Columbia (B.C.), plants were sampled from three sites: a Betula-dominated site and two sites with a mixture of conifer and hardwood trees. Fifteen M. uniflora root-clusters were sampled (five per site) and the mycorrhizal diversity was assessed using morphological and molecular (PCR-RFLP analysis and DNA sequencing) methods. Both methods showed that root-clusters (often comprising several hundred mycorrhizal tips) belonging to the same plant appeared to involve fungus monocultures in the family Russulaceae. All mycorrhizae exhibited typical Russula morphology and had mantle cystidia. Two root-clusters, one each from sites 1 and 3, lacked one of the two types of cystidia present on all other root-clusters. PCR-RFLP analysis resulted in three fragment patterns for the 15 root clusters. One molecular fragment pattern included the two root-clusters displaying the single cystidium type plus an additional root-cluster with both cystidia types. DNA sequencing of a portion of the ITS2 region of the ribosomal DNA suggests that the three variants represent different species; two of the variants clustered with the hypogeous fungi Martellia and Gymnomyces. The study provides increased evidence of low diversity and high specificity in the Monotropa-fungus relationship and suggests that M. uniflora associates uniquely with fungi in the family Russulaceae in central B.C.     

组学技术在核盘菌研究中的应用

核盘菌Sclerotinia sclerotiorum是一种典型的死体营养型植物病原真菌,全球分布且寄主范围广泛,严重危害多种植物,对农业生产造成严重损失。核盘菌研究主要集中在真菌生物学及病理学等方面。近年来,随着高通量分析技术的不断改进,多种组学技术为系统生物学研究提供了平台。文中主要综述利用多种组学研究方法在植物病原真菌核盘菌研究中的应用及研究进展,探讨开展植物病原物及病害发展的系统性研究思路,以期为核盘菌的分子生物学及致病机理等研究提供参考,同时也为其他植物病原物及病害系统研究提供理论依据。     

WHAT SHALL WE DO WITH THE BLUE-GREEN COUNTERPARTS?

Lichens are troublesome organisms for taxonomists because of their special ‘ double nature ’, i.e. being composed (normally) of two partners. Only recently has it been understood properly that the same fungus can take different photosynthetic partners and develop into quite different-looking organisms, for exampleLobaria amplissimaandDendriscocaulon umhausense. The taxonomic problem is to show that two totally different-looking lichens in fact contain the same fungus. This is possible to demonstrate when mixed stands are available, but is now best done with molecular methods. Since the international code of nomenclature rules that the name of a lichen species is the name of the fungus, two different organisms with the same fungus must under the Code carry the same name, which is most impractical. To remove this unintentional complication, one must either make an exception in the Code for these cases, or establish an informal system to take care of them. The latter seems to be preferable.     

外生菌根菌与森林树木的相互关系

生态系统的每个过程都伴随着各种微生物的活动,其中最重要的功能群之一是菌根真菌(菌根菌)。一般认为,菌根菌是自然界多数植物生存最基本的组成部分,陆地上约90％以上的高等植物都具有菌根菌。这些菌类的菌丝体与植物根系结合形成菌根,使植物生长成为可能,使不同种类植物的根系联在一起。根据菌根菌入侵植物根系的方式及菌根的形态特征,菌根可分为外生菌根、内生菌根和内外生菌根3组共7种类型。外生菌根主要出现在松科、桦木科、壳斗科等树种的森林生态系统中,在根系表面形成菌丝鞘,部分菌丝进入根系皮层细胞间隙形成哈氏网表面。菌根菌剂在森林经营中得到广泛地应用。外生菌根菌对森林树木的作用可归纳为：1)促进造林或育苗成活与生长;2)提高森林生态系统中植物的多样性、稳定性和生产力;3)对森林生态系统的综合效应,主要表现在增加植物一土壤联结,改善土壤结构,促进土壤微生物,增强植物器官的功能;4)抗拮植物根部病害病原菌等。树木与菌根菌相互关系研究主要包括：1)菌根共生的机理;2)菌根菌在退化森林生态系统恢复与改造中的作用;3)菌根菌的分布格局与森林生态系统服务功能的关系;4)菌根菌对森林生态系统的综合效应,如菌根菌与森林植物群落结构、物种多样性以及森林系统稳定性和生产力的研究。     

Heat tolerant fungi and applied research: Addition to the previously treated group of strictly thermotolerant species

Heat tolerant fungi are organisms that may perform bioconversion processes and produce industrially important metabolites. They may either be obligate thermophiles or simple thermotolerants. The present document is the continuation of a critical note on thermotolerant fungi erroneously reported in the literature as possessing thermophilic attributes. Fifty strictly thermotolerant taxa are here considered. Some of their binomials have only recently been introduced in the scientific literature. The reported thermotolerant species are grouped according to broad taxonomic categories. The nomenclature of zygomycetous taxa and anamorphic fungi is straightforward, as usually only one binomial is available or only one state is produced in culture respectively. For Ascomycetes regularly producing in culture a conidial state, the name of the sexual state (teleomorph) should be used to designate the organism even when a binomial is available for the anamorph; this prevents the practice of interchangeably using the name of either states of the same fungus. When ascomycetous taxa produce the anamorph regularly and the teleomorph only under specific cultural conditions, the name of the anamorph could be preferentially selected. The goal is to introduce uniformity in name citations of fungi, particularly in the literature of applied research. Each species is reported under its taxonomically correct name, either the original binomial or the latest combined binomial after generic transfer(s). Known synonyms are also specified. Maximum efforts were undertaken to trace updated information on the taxonomic position of these fifty strict thermotolerant species. For each, information on the type material, morphological features distinguishing it from related members of the genus (and when necessary a generic taxonomic assessment) and, finally, salient ecological features including heat tolerance levels are given. For some information on their biotechnological use is also provided. Overall 86 strictly thermotolerant fungi are so far documented in the corresponding published and present contributions; however, this figure should not be regarded as exhaustive for the group. Among these 86 taxa ascomycetous fungi (46) presently outnumber anamorphic microfungi (28) but their relevant figures should be regarded as provisional. Only 12 zygomycetous species proved to be strict thermotolerants. Further cardinal temperature growth values established for these 86 thermotolerants disclose no pattern linked to their broad taxonomic categories. Standardized growth temperature curves at increments smaller than 5 °C have to be performed to assess conclusively variability in growth temperature relationships. Several heat tolerant fungi are widely used in industry; however, more research is needed to explore the applied potential of these particular organisms. An exhaustive document on the biodiversity of heat tolerant fungi also awaits production. It would be informative in relation to the global warming process of the earth.     

The aldo-keto reductase (AKR) superfamily: an update

The aldo-keto reductases (AKRs) are one of three enzyme superfamilies encompassing a range of oxidoreductases. Members of the AKR superfamily are monomeric (alpha/beta)(8)-barrel proteins, about 320 amino acids in length, which bind NAD(P)(H) to metabolize an array of substrates. AKRs have been identified in vertebrates, invertebrates, plants, protozoa, fungi, eubacteria, and archaebacteria, implying that this is an ancient superfamily of enzymes. Earlier, in an attempt to clarify the confusion caused by multiple names for particular AKRs, we proposed a systematic and expandable nomenclature system to assign consistent designations to unique members of the AKR superfamily. Since then, the number of characterized AKRs has expanded to 105 proteins in 12 families. In addition, molecular cloning and genome sequencing projects have identified 125 potential AKR genes, many of which have no assigned function. The nomenclature system for the AKR superfamily is accepted by the Human Genome Project. Using the earlier described nomenclature system, we now provide an updated listing of AKRs and potential superfamily members.     

Hiding in a crowd—does diversity facilitate persistence of a low-quality fungal partner in the mycorrhizal symbiosis?

Given that arbuscular mycorrhizal (AM) fungi are not consistently beneficial to their host plants, it is difficult to explain the evolutionary persistence of this relationship. We tested the hypothesis that increasing either fungal or host biodiversity allows an AM fungus to persist on a host where it shows little benefit. We found that growing such a fungus (an isolate of Glomus custos associating with Plantago laceolata) in combination with certain fungi improved its success as measured by mtLSU DNA abundance. Increasing plant species richness facilitated the spread of this fungus as measured by spore density and fungal colonization; the role of host species richness was not as clear when looking at measures of root abundance. These results indicate that diversity in the AM symbiosis, both plant and fungal, can promote the persistence of low-quality fungi. By existing within a complex mycelial network fungal strains that show little growth benefit to their hosts have a better chance of persisting on that same host. This has the potential to promote selection for heterogeneous AM fungal communities on a small spatial scale.