Comparative genomics of the closely related fungal genera Cryptococcus and Kwoniella reveals karyotype dynamics and suggests evolutionary mechanisms of pathogenesis.

In exploring the evolutionary trajectories of both pathogenesis and karyotype dynamics in fungi, we conducted a large-scale comparative genomic analysis spanning the Cryptococcus genus, encompassing both global human fungal pathogens and nonpathogenic species, and related species from the sister genus Kwoniella. Chromosome-level genome assemblies were generated for multiple species, covering virtually all known diversity within these genera. Although Cryptococcus and Kwoniella have comparable genome sizes (about 19.2 and 22.9 Mb) and similar gene content, hinting at preadaptive pathogenic potential, our analysis found evidence of gene gain (via horizontal gene transfer) and gene loss in pathogenic Cryptococcus species, which might represent evolutionary signatures of pathogenic development. Genome analysis also revealed a significant variation in chromosome number and structure between the 2 genera. By combining synteny analysis and experimental centromere validation, we found that most Cryptococcus species have 14 chromosomes, whereas most Kwoniella species have fewer (11, 8, 5, or even as few as 3). Reduced chromosome number in Kwoniella is associated with formation of giant chromosomes (up to 18 Mb) through repeated chromosome fusion events, each marked by a pericentric inversion and centromere loss. While similar chromosome inversion-fusion patterns were observed in all Kwoniella species with fewer than 14 chromosomes, no such pattern was detected in Cryptococcus. Instead, Cryptococcus species with less than 14 chromosomes showed reductions primarily through rearrangements associated with the loss of repeat-rich centromeres. Additionally, Cryptococcus genomes exhibited frequent interchromosomal translocations, including intercentromeric recombination facilitated by transposons shared between centromeres. Overall, our findings advance our understanding of genetic changes possibly associated with pathogenicity in Cryptococcus and provide a foundation to elucidate mechanisms of centromere loss and chromosome fusion driving distinct karyotypes in closely related fungal species, including prominent global human pathogens.

Safety and efficacy of a feed additive consisting of muramidase produced with Trichoderma reesei DSM 32338 (Balancius™) for laying hens (DSM nutritional products).

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of muramidase produced with Trichoderma reesei DSM 32338 (Balancius™) as a feed additive for laying hens. The additive is already authorised as a zootechnical additive (functional group: other zootechnical additives) for chickens, turkeys and minor poultry species for fattening or reared for breeding, and for weaned piglets. The enzyme is produced by fermentation with a genetically modified strain of Trichoderma reesei; viable cells of the production strain and its recombinant DNA were not detected in the additive. The EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) concluded that the additive does not give rise to safety concerns regarding the genetic modification of the production strain. Based on the data available from a sub-chronic oral toxicity study, the Panel concluded that the additive is safe for laying hens at the maximum recommended level of 60,000 LSU(F) (muramidase activity units)/kg feed. The Panel also concluded that the additive is safe for the consumers and the environment. The liquid formulation of the additive is considered not irritant to the skin or eyes. The solid formulation of the additive is considered not irritant to the skin. The Panel cannot conclude on the potential of the additive (both formulations) to be a dermal sensitiser or on the potential of the solid formulation to be irritant to the eyes. Due to the proteinaceous nature, both forms of the additive should be considered respiratory sensitisers. The additive has the potential to be efficacious as a zootechnical additive for laying hens at 30,000 LSU(F)/kg feed.

Safety and efficacy of a feed additive consisting of Saccharomyces cerevisiae DSM 34246 (Canobios-BL) for cats and dogs (ACEL pharma s.r.l.).

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of Saccharomyces cerevisiae DSM 34246 as a zootechnical feed additive for dogs and cats. The additive, with the trade name Canobios-BL, is intended for use in feed for cats and dogs at a proposed minimum inclusion level of 5 × 109 CFU/kg complete feed. Saccharomyces cerevisiae is considered by EFSA to be suitable for the qualified presumption of safety approach to safety assessment. Since the identity of the active agent has been clearly established and the additive is composed by dried cells of the active agent and an emulsifier, that are not expected to introduce any risk, the additive is considered safe for the target species. Canobios-BL is not a skin or eye irritant but should be considered a skin and respiratory sensitiser. Canobios-BL is considered to be efficacious in feedingstuffs for dogs and cats at the use level 5 × 109 CFU/kg complete feed.

Safety and efficacy of a feed additive consisting of endo-1,4-ß xylanase, endo-1,4-ß-glucanase and xyloglucan-specific-endo-ß-1,4-glucanase produced by Trichoderma citrinoviride DSM 33578 (Huvezym® neXo) for all Suidae (Huvepharma EOOD).

Following a request from the European Commission, the EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) was asked to deliver a scientific opinion on the safety and efficacy of Huvezym® neXo 100 G/L, a product containing endo-1,4-ß-xylanase, endo-1,4-ß-glucanase and xyloglucan-specific-endo-ß-1,4-glucanase activities produced by a non-genetically modified strain of Trichoderma citrinoviride (DSM 33578), as a zootechnical additive for all Suidae. The applicant provided information confirming the taxonomic identification of the production strain. The batches used for the characterisation of the final formulations showed compliance with the minimum specifications of the additive in terms of enzyme activities (> 15,000 EPU, > 1000 CU, > 1000 XGU per g) but not for the ratio of the enzymes, which is lower (ca. 7:1:1) than the ones specified (15:1:1). The Panel could not conclude on the representativeness of the test item used in the toxicological and tolerance studies with respect to the final formulations. Therefore, the conclusions are limited to the product with a minimum enzyme activity of 15,000 EPU, 1000 CU, 1000 XGU per g and a xylanase:glucanase:xyloglucanase ratio of 15:1:1. The Panel concluded that the additive is safe for the target species, consumers and the environment. Huvezym® neXo 100 G is not an irritant to the skin and eyes but should be considered a skin sensitiser. Huvezym® neXo 100 L is neither an irritant to the skin and eyes nor a skin sensitiser. Due to the proteinaceous nature of the active substances, the additive is considered a respiratory sensitiser. The additive has the potential to be efficacious in all reproductive Suidae at the minimum proposed use level. Owing to the lack of sufficient data, the Panel could not conclude on the efficacy of the additive for Suidae for fattening or reared for reproduction.

Comparative genomics of Cryptococcus and Kwoniella reveals pathogenesis evolution and contrasting karyotype dynamics via intercentromeric recombination or chromosome fusion.

A large-scale comparative genomic analysis was conducted for the global human fungal pathogens within the Cryptococcus genus, compared to non-pathogenic Cryptococcus species, and related species from the sister genus Kwoniella. Chromosome-level genome assemblies were generated for multiple species of both genera, resulting in a dataset encompassing virtually all of their known diversity. Although Cryptococcus and Kwoniella have comparable genome sizes (about 19.2 and 22.9 Mb) and similar gene content, hinting at pre-adaptive pathogenic potential, our analysis found evidence in pathogenic Cryptococcus species of specific examples of gene gain (via horizontal gene transfer) and gene loss, which might represent evolutionary signatures of pathogenic development. Genome analysis also revealed a significant variation in chromosome number and structure between the two genera. By combining synteny analysis and experimental centromere validation, we found that most Cryptococcus species have 14 chromosomes, whereas most Kwoniella species have fewer (11, 8, 5 or even as few as 3). Reduced chromosome number in Kwoniella is associated with formation of giant chromosomes (up to 18 Mb) through repeated chromosome fusion events, each marked by a pericentric inversion and centromere loss. While similar chromosome inversion-fusion patterns were observed in all Kwoniella species with fewer than 14 chromosomes, no such pattern was detected in Cryptococcus. Instead, Cryptococcus species with less than 14 chromosomes, underwent chromosome reductions primarily through rearrangements associated with the loss of repeat-rich centromeres. Additionally, Cryptococcus genomes exhibited frequent interchromosomal translocations, including intercentromeric recombination facilitated by transposons shared between centromeres. Taken together, our findings advance our understanding of genomic changes possibly associated with pathogenicity in Cryptococcus and provide a foundation to elucidate mechanisms of centromere loss and chromosome fusion driving distinct karyotypes in closely related fungal species, including prominent global human pathogens.

Fungi under Modified Atmosphere-The Effects of CO2 Stress on Cell Membranes and Description of New Yeast Stenotrophomyces fumitolerans gen. nov., sp. nov.

High levels of carbon dioxide are known to inhibit the growth of microorganisms. A total of twenty strains of filamentous fungi and yeasts were isolated from habitats with enriched carbon dioxide concentration. Most strains were derived from modified atmosphere packed (MAP) food products or mofettes and were cultivated under an atmosphere of 20% CO2 and 80% O2. The influence of CO2 on fungal cell membrane fatty acid profiles was examined in this study. Major changes were the increase in linolenic acid (C18:3 cis 9, 12, 15) and, additionally in most strains, linoleic acid (C18:2 cis 9, 12) with a maximum of 24.8%, at the expense of oleic (C18:1 cis 9), palmitic (C16:0), palmitoleic (C16:1 cis 9) and stearic acid (C18:0). The degree of fatty acid unsaturation increased for all of the strains in the study, which consequently led to lower melting temperatures of the cell membranes after incubation with elevated levels of CO2, indicating fluidization of the membrane and a potential membrane malfunction. Growth was reduced in 18 out of 20 strains in laboratory experiments and a change in pigmentation was observed in several strains. Two of the isolated strains, strain WT5 and strain WR1, were found to represent a hitherto undescribed yeast for which the new genus and species Stenotrophomyces fumitolerans (MB# 849906) is proposed.

The Effects of Rhizophagus irregularis Inoculation on Transcriptome of Medicago lupulina Leaves at Early Vegetative and Flowering Stages of Plant Development.

The study is aimed at revealing the effects of Rhizophagus irregularis inoculation on the transcriptome of Medicago lupulina leaves at the early (second leaf formation) and later (flowering) stages of plant development. A pot experiment was conducted under conditions of low phosphorus (P) level in the substrate. M. lupulina plants were characterized by high mycorrhizal growth response and mycorrhization parameters. Library sequencing was performed on the Illumina HiseqXTen platform. Significant changes in the expression of 4863 (padj < 0.01) genes from 34049 functionally annotated genes were shown by Massive Analysis of cDNA Ends (MACE-Seq). GO enrichment analysis using the Kolmogorov-Smirnov test was performed, and 244 functional GO groups were identified, including genes contributing to the development of effective AM symbiosis. The Mercator online tool was used to assign functional classes of differentially expressed genes (DEGs). The early stage was characterized by the presence of six functional classes that included only upregulated GO groups, such as genes of carbohydrate metabolism, cellular respiration, nutrient uptake, photosynthesis, protein biosynthesis, and solute transport. At the later stage (flowering), the number of stimulated GO groups was reduced to photosynthesis and protein biosynthesis. All DEGs of the GO:0016036 group were downregulated because AM plants had higher resistance to phosphate starvation. For the first time, the upregulation of genes encoding thioredoxin in AM plant leaves was shown. It was supposed to reduce ROS level and thus, consequently, enhance the mechanisms of antioxidant protection in M. lupulina plants under conditions of low phosphorus level. Taken together, the obtained results indicate genes that are the most important for the effective symbiosis with M. lupulina and might be engaged in other plant species.

Genomic characterization and radiation tolerance of Naganishia kalamii sp. nov. and Cystobasidium onofrii sp. nov. from Mars 2020 mission assembly facilities.

During the construction and assembly of the Mars 2020 mission components at two different NASA cleanrooms, several fungal strains were isolated. Based on their colony morphology, two strains that showed yeast-like appearance were further characterized for their phylogenetic position. The species-level classification of these two novel strains, using traditional colony and cell morphology methods combined with the phylogenetic reconstructions using multi-locus sequence analysis (MLSA) based on several gene loci (ITS, LSU, SSU, RPB1, RPB2, CYTB and TEF1), and whole genome sequencing (WGS) was carried out. This polyphasic taxonomic approach supported the conclusion that the two basidiomycetous yeasts belong to hitherto undescribed species. The strain FJI-L2-BK-P3T, isolated from the Jet Propulsion Laboratory Spacecraft Assembly Facility, was placed in the Naganishia albida clade (Filobasidiales, Tremellomycetes), but is genetically and physiologically different from other members of the clade. Another yeast strain FKI-L6-BK-PAB1T, isolated from the Kennedy Space Center Payload Hazardous and Servicing Facility, was placed in the genus Cystobasidium (Cystobasidiales, Cystobasidiomycetes) and is distantly related to C. benthicum. Here we propose two novel species with the type strains, Naganishia kalamii sp. nov. (FJI-L2-BK-P3T = NRRL 64466 = DSM 115730) and Cystobasidium onofrii sp. nov. (FKI-L6-BK-PAB1T = NRRL 64426 = DSM 114625). The phylogenetic analyses revealed that single gene phylogenies (ITS or LSU) were not conclusive, and MLSA and WGS-based phylogenies were more advantageous for species discrimination in the two genera. The genomic analysis predicted proteins associated with dehydration and desiccation stress-response and the presence of genes that are directly related to osmotolerance and psychrotolerance in both novel yeasts described. Cells of these two newly-described yeasts were exposed to UV-C radiation and compared with N. onofrii, an extremophilic UV-C resistant cold-adapted Alpine yeast. Both novel species were UV resistant, emphasizing the need for collecting and characterizing extremotolerant microbes, including yeasts, to improve microbial reduction techniques used in NASA planetary protection programs.

Species and temperature-dependent fermentative aptitudes of Mrakia genus for innovative brewing.

The use of non-conventional brewing yeasts as alternative starters is a very promising approach which received increasing attention from worldwide scientists and brewers. Despite the feasible application of non-conventional yeasts in brewing processes, their regulations and safety assessment by the European Food Safety Authority still represent a bottlenecked hampering their commercial release, at least into EU market. Thus, research on yeast physiology, accurate taxonomic species identification and safety concerns associated with the use of non-conventional yeasts in food chains is needed to develop novel healthier and safer beers. Currently, most of the documented brewing applications catalysed by non-conventional yeasts are associated to ascomycetous yeasts, while little is known about analogous uses of basidiomycetous taxa. Therefore, in order to extend the phenotypic diversity of basidiomycetous brewing yeasts the aim of this investigation is to check the fermentation aptitudes of thirteen Mrakia species in relation to their taxonomic position within the genus Mrakia. The volatile profile, ethanol content and sugar consumption were compared with that produced by a commercial starter for low alcohol beers, namely Saccharomycodes ludwigii WSL 17. The phylogeny of Mrakia genus showed three clusters that clearly exhibited different fermentation aptitudes. Members of M. gelida cluster showed a superior aptitude to produce ethanol, higher alcohols, esters and sugars conversion compared to the members of M. cryoconiti and M. aquatica clusters. Among M. gelida cluster, the strain M. blollopis DBVPG 4974 exhibited a medium flocculation profile, a high tolerance to ethanol and to iso-α-acids, and a considerable production of lactic and acetic acids, and glycerol. In addition, an inverse relationship between fermentative performances and incubation temperature is also displayed by this strain. Possible speculations on the association between the cold adaptation exhibited by M. blollopis DBVPG 4974 and the release of ethanol in the intracellular matrix and in the bordering environment are presented.

Diddensiella parasantjacobensis f.a., sp. nov., a yeast species from forest habitats.

Six conspecific yeast strains, representing an undescribed species, were isolated from rotten wood collected in different locations in Hungary and Germany and an additional one from fungal fruiting body in Taiwan. The seven strains share identical nucleotide sequences in the D1/D2 domain of the nuclear large subunit (LSU) rRNA gene. The Hungarian and Taiwanese isolates share identical internal transcribed spacer (ITS) sequences as well, while the two German isolates differ from them merely by three substitutions and four indels in this region. The investigated strains are very closely related to Diddensiella santjacobensis. Along their LSU D1/D2 domain they differ only by one substitution from the type strain of D. santjacobensis. However, in the ITS region of Hungarian and Taiwanese strains we detected 3.5 % divergence (nine substitutions and nine indels) between the undescribed species and D. santjacobensis, while the German strains differed by 13 substitutions and nine indels from D. santjacobensis. This ITS sequence divergence has raised the possibility that the strains investigated in this study may represent a different species from D. santjacobensis. This hypothesis was supported by comparisons of partial translation elongation factor 1-α (EF-1α) and cytochrome oxidase II (COX II) gene sequences. While no difference and 1-2 substitutions among the partial EF-1α and COX II gene sequences of the strains of the undescribed species, respectively, were detected; the undescribed species differ by about 4 % (36 substitutions) and 10 % (50-51 substitutions) from D. santjacobensis in these regions. Parsimony network analysis of the partial COX II gene sequences also separated the investigated strains from the type strain of D. santjacobensis. In this paper we propose Diddensiella parasantjacobensis f.a., sp. nov. (holotype: NCAIM Y.02121; isotypes: CBS 17819, DSM 114156) to accommodate the above-noted strains.

How legislations affect new taxonomic descriptions.

Restrictions placed on the distribution of biological material by the legislation of countries such as India, South Africa, or Brazil exclude strains that could serve as type material for the validation or valid publication of prokaryotic species names. This problem goes beyond prokaryotic taxonomy and is also relevant for other areas of biological research.

Diversity of Arbuscular Mycorrhizal Fungi in Distinct Ecosystems of the North Caucasus, a Temperate Biodiversity Hotspot.

BACKGROUND: Investigations that are focused on arbuscular mycorrhizal fungus (AMF) biodiversity is still limited. The analysis of the AMF taxa in the North Caucasus, a temperate biodiversity hotspot, used to be limited to the genus level. This study aimed to define the AMF biodiversity at the species level in the North Caucasus biotopes. METHODS: The molecular genetic identification of fungi was carried out with ITS1 and ITS2 regions as barcodes via sequencing using Illumina MiSeq, the analysis of phylogenetic trees for individual genera, and searches for operational taxonomic units (OTUs) with identification at the species level. Sequences from MaarjAM and NCBI GenBank were used as references. RESULTS: We analyzed >10 million reads in soil samples for three biotopes to estimate fungal biodiversity. Briefly, 50 AMF species belonging to 20 genera were registered. The total number of the AM fungus OTUs for the "Subalpine Meadow" biotope was 171/131, that for "Forest" was 117/60, and that for "River Valley" was 296/221 based on ITS1/ITS2 data. The total number of the AM fungus species (except for virtual taxa) for the "Subalpine Meadow" biotope was 24/19, that for "Forest" was 22/13, and that for "River Valley" was 28/24 based on ITS1/ITS2 data. Greater AMF diversity, as well as number of OTUs and species, in comparison with that of forest biotopes, characterized valley biotopes (disturbed ecosystems; grasslands). The correlation coefficient between "Percentage of annual plants" and "Glomeromycota total reads" r = 0.76 and 0.81 for ITS1 and ITS2, respectively, and the correlation coefficient between "Percentage of annual plants" and "OTUs number (for total species)" was r = 0.67 and 0.77 for ITS1 and ITS2, respectively. CONCLUSION: High AMF biodiversity for the river valley can be associated with a higher percentage of annual plants in these biotopes and the active development of restorative successional processes.

Safety and efficacy of a feed additive consisting of endo-1,4-beta xylanase, endo-1,4-beta-glucanase and xyloglucan-specific-endo-beta-1,4-glucanase produced by Trichoderma citrinovirideDSM 33578 (Huvezym® neXo 100 G/L) for all poultry species, ornamental birds and piglets (weaned and suckling) (Huvepharma EOOD).

Following a request from the European Commission, the EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) was asked to deliver a scientific opinion on the safety and efficacy of the product Huvezym® neXo 100 G/L containing an endo-1,4-beta xylanase, an endo-1,4-beta-glucanase and a xyloglucan-specific-endo-beta-1,4-glucanase produced by a non-genetically modified strain of Trichoderma citrinoviride (DSM 33578) as a zootechnical additive for feed in all poultry species, ornamental birds and piglets (weaned and suckling). The information regarding the production strain did not allow to confirm its taxonomic identification. The batches used for the characterisation of the final formulations showed compliance with the minimum specifications of the additive in terms of enzyme activities but showed ratios between the enzymes lower than the ones specified for the additive. The FEEDAP Panel considered that the below-described conclusions would apply to the final formulations of the additive as per specifications with xylanase:glucanase, xylanase:xyloglucanase and glucanase:xyloglucanase ratios of 15, 15 and 1, respectively. Based on the data available, the Panel concluded that the additive is safe for the target species, consumers and the environment. Huvezym® neXo 100 G (granulated form) is neither skin corrosive nor eye irritant but should be considered a potential skin sensitiser. Huvezym® neXo 100 L (liquid) is neither skin corrosive nor sensitising and it is not an eye irritant. Due to lack of data, no conclusions can be drawn on the skin irritation of the final formulations of the additive. Due to the proteinaceous nature of the active substances, the additive is considered a respiratory sensitiser. The FEEDAP Panel concluded that the additive has the potential to be efficacious in chickens for fattening, chickens reared for laying and breeding, and all growing poultry and ornamental birds at the minimum intended level of 1,500 EPU, 100 CU and 100 XGU/kg complete feed. Owing to the lack of sufficient data, the Panel could not conclude on the efficacy of the additive for laying hens and weaned piglets.

The Role of Medicago lupulina Interaction with Rhizophagus irregularis in the Determination of Root Metabolome at Early Stages of AM Symbiosis.

The nature of plant-fungi interaction at early stages of arbuscular mycorrhiza (AM) development is still a puzzling problem. To investigate the processes behind this interaction, we used the Medicago lupulina MlS-1 line that forms high-efficient AM symbiosis with Rhizophagus irregularis. AM fungus actively colonizes the root system of the host plant and contributes to the formation of effective AM as characterized by a high mycorrhizal growth response (MGR) in the host plant. The present study is aimed at distinguishing the alterations in the M. lupulina root metabolic profile as an indicative marker of effective symbiosis. We examined the root metabolome at the 14th and 24th day after sowing and inoculation (DAS) with low substrate phosphorus levels. A GS-MS analysis detected 316 metabolites. Results indicated that profiles of M. lupulina root metabolites differed from those in leaves previously detected. The roots contained fewer sugars and organic acids. Hence, compounds supporting the growth of mycorrhizal fungus (especially amino acids, specific lipids, and carbohydrates) accumulated, and their presence coincided with intensive development of AM structures. Mycorrhization determined the root metabolite profile to a greater extent than host plant development. The obtained data highlight the importance of active plant-fungi metabolic interaction at early stages of host plant development for the determination of symbiotic efficiency.

Yeasts from temperate forests.

Yeasts are ubiquitous in temperate forests. While this broad habitat is well-defined, the yeasts inhabiting it and their life cycles, niches, and contributions to ecosystem functioning are less understood. Yeasts are present on nearly all sampled substrates in temperate forests worldwide. They associate with soils, macroorganisms, and other habitats and no doubt contribute to broader ecosystem-wide processes. Researchers have gathered information leading to hypotheses about yeasts' niches and their life cycles based on physiological observations in the laboratory as well as genomic analyses, but the challenge remains to test these hypotheses in the forests themselves. Here, we summarize the habitat and global patterns of yeast diversity, give some information on a handful of well-studied temperate forest yeast genera, discuss the various strategies to isolate forest yeasts, and explain temperate forest yeasts' contributions to biotechnology. We close with a summary of the many future directions and outstanding questions facing researchers in temperate forest yeast ecology. Yeasts present an exciting opportunity to better understand the hidden world of microbial ecology in this threatened and global habitat.

The evolving species concepts used for yeasts: from phenotypes and genomes to speciation networks.

Here we review how evolving species concepts have been applied to understand yeast diversity. Initially, a phenotypic species concept was utilized taking into consideration morphological aspects of colonies and cells, and growth profiles. Later the biological species concept was added, which applied data from mating experiments. Biophysical measurements of DNA similarity between isolates were an early measure that became more broadly applied with the advent of sequencing technology, leading to a sequence-based species concept using comparisons of parts of the ribosomal DNA. At present phylogenetic species concepts that employ sequence data of rDNA and other genes are universally applied in fungal taxonomy, including yeasts, because various studies revealed a relatively good correlation between the biological species concept and sequence divergence. The application of genome information is becoming increasingly common, and we strongly recommend the use of complete, rather than draft genomes to improve our understanding of species and their genome and genetic dynamics. Complete genomes allow in-depth comparisons on the evolvability of genomes and, consequently, of the species to which they belong. Hybridization seems a relatively common phenomenon and has been observed in all major fungal lineages that contain yeasts. Note that hybrids may greatly differ in their post-hybridization development. Future in-depth studies, initially using some model species or complexes may shift the traditional species concept as isolated clusters of genetically compatible isolates to a cohesive speciation network in which such clusters are interconnected by genetic processes, such as hybridization.

Mycorrhiza-Induced Alterations in Metabolome of Medicago lupulina Leaves during Symbiosis Development.

The present study is aimed at disclosing metabolic profile alterations in the leaves of the Medicago lupulina MlS-1 line that result from high-efficiency arbuscular mycorrhiza (AM) symbiosis formed with Rhizophagus irregularis under condition of a low phosphorus level in the substrate. A highly effective AM symbiosis was established in the period from the stooling to the shoot branching initiation stage (the efficiency in stem height exceeded 200%). Mycorrhization led to a more intensive accumulation of phosphates (glycerophosphoglycerol and inorganic phosphate) in M. lupulina leaves. Metabolic spectra were detected with GS-MS analysis. The application of complex mathematical analyses made it possible to identify the clustering of various groups of 320 metabolites and thus demonstrate the central importance of the carbohydrate and carboxylate-amino acid clusters. The results obtained indicate a delay in the metabolic development of mycorrhized plants. Thus, AM not only accelerates the transition between plant developmental stages but delays biochemical "maturation" mainly in the form of a lag of sugar accumulation in comparison with non-mycorrhized plants. Several methods of statistical modeling proved that, at least with respect to determining the metabolic status of host-plant leaves, stages of phenological development have priority over calendar age.

Nomenclatural issues concerning cultured yeasts and other fungi: why it is important to avoid unneeded name changes.

The unambiguous application of fungal names is important to communicate scientific findings. Names are critical for (clinical) diagnostics, legal compliance, and regulatory controls, such as biosafety, food security, quarantine regulations, and industrial applications. Consequently, the stability of the taxonomic system and the traceability of nomenclatural changes is crucial for a broad range of users and taxonomists. The unambiguous application of names is assured by the preservation of nomenclatural history and the physical organisms representing a name. Fungi are extremely diverse in terms of ecology, lifestyle, and methods of study. Predominantly unicellular fungi known as yeasts are usually investigated as living cultures. Methods to characterize yeasts include physiological (growth) tests and experiments to induce a sexual morph; both methods require viable cultures. Thus, the preservation and availability of viable reference cultures are important, and cultures representing reference material are cited in species descriptions. Historical surveys revealed drawbacks and inconsistencies between past practices and modern requirements as stated in the International Code of Nomenclature for Algae, Fungi, and Plants (ICNafp). Improper typification of yeasts is a common problem, resulting in a large number invalid yeast species names. With this opinion letter, we address the problem that culturable microorganisms, notably some fungi and algae, require specific provisions under the ICNafp. We use yeasts as a prominent example of fungi known from cultures. But viable type material is important not only for yeasts, but also for other cultivable Fungi that are characterized by particular morphological structures (a specific type of spores), growth properties, and secondary metabolites. We summarize potential proposals which, in our opinion, will improve the stability of fungal names, in particular by protecting those names for which the reference material can be traced back to the original isolate.