Largest Subunit Of RNA Polymerase Research Articles

Oxidative stress induces Ser 2 dephosphorylation of the RNA polymerase II CTD and premature transcription termination

ABSTRACT The C-terminal domain (CTD) of the largest subunit of RNA polymerase II (Pol II) consists of YSPTSPS heptapeptide repeats, and the phosphorylation status of the repeats controls multiple transcriptional steps and co-transcriptional events. However, how CTD phosphorylation status responds to distinct environmental stresses is not fully understood. In this study, we found that a drastic reduction in phosphorylation of a subset of Ser2 residues occurs rapidly but transiently following exposure to H2O2. ChIP analysis indicated that Ser2-P, and to a lesser extent Tyr1-P was reduced only at the gene 3’ end. Significantly, the levels of polyadenylation factor CstF77, as well as Pol II, were also reduced. However, no increase in uncleaved or readthrough RNA products was observed, suggesting transcribing Pol II prematurely terminates at the gene end in response to H2O2. Further analysis found that the reduction of Ser2-P is, at least in part, regulated by CK2 but independent of FCP1 and other known Ser2 phosphatases. Finally, the H2O2 treatment also affected snRNA 3’ processing although surprisingly the U2 processing was not impaired. Together, our data suggest that H2O2 exposure creates a unique CTD phosphorylation state that rapidly alters transcription to deal with acute oxidative stress, perhaps creating a novel “emergency brake” mechanism to transiently dampen gene expression.

PHF3 regulates neuronal gene expression through the Pol II CTD reader domain SPOC

The C-terminal domain (CTD) of the largest subunit of RNA polymerase II (Pol II) is a regulatory hub for transcription and RNA processing. Here, we identify PHD-finger protein 3 (PHF3) as a regulator of transcription and mRNA stability that docks onto Pol II CTD through its SPOC domain. We characterize SPOC as a CTD reader domain that preferentially binds two phosphorylated Serine-2 marks in adjacent CTD repeats. PHF3 drives liquid-liquid phase separation of phosphorylated Pol II, colocalizes with Pol II clusters and tracks with Pol II across the length of genes. PHF3 knock-out or SPOC deletion in human cells results in increased Pol II stalling, reduced elongation rate and an increase in mRNA stability, with marked derepression of neuronal genes. Key neuronal genes are aberrantly expressed in Phf3 knock-out mouse embryonic stem cells, resulting in impaired neuronal differentiation. Our data suggest that PHF3 acts as a prominent effector of neuronal gene regulation by bridging transcription with mRNA decay.

Syndromic RNA polymerase II insufficiency: Generation of a human induced pluripotent stem cell line (UUIGPi002A-5) with a heterozygous disruption of POLR2A

Heterozygous variants in POLR2A, encoding the largest subunit of RNA polymerase II, cause severe neurodevelopmental and multisystem abnormalities in humans. Using CRISPR/Cas9 we generated the human iPSC line KICRi002A-5 with a heterozygous truncating 4 bp insertion in exon 5 of the POLR2A gene. Analysis using qRT-PCR confirmed reduced POLR2A mRNA in KICRi002A-5 vs. the isogenic WT iPSC line. The edited iPSC line expressed pluripotency markers and exhibited differentiation capacity into the three germ layers. Assessment of genomic integrity revealed a normal karyotype and OFF-target editing was excluded. The iPSC line KICRi002A-5 provides a useful resource to study mechanisms underlying developmental defects caused by RBP1 insufficiency.

NOVEL SPECIFIC PRIMERS FOR THE SPECIFIC DETECTION OF FUSARIUM OXYSPORUM F. SP. CUBENSE BASED ON SYBR GREEN REAL-TIME PCR

Fusarium oxysporum f. sp. cubense (Foc) is the causal agent of Fusarium wilt of banana worldwide. Foc is transmitted to another banana plantation via an infected banana sucker. A specific and sensitive detection assay could be used for disease-free propagule screening to prevent disease dispersal effectively. In this study, SYBR green-based real-time PCR assay was developed based on novel specific primers targeting the large subunit of RNA polymerase II (RPB1) gene. The partial RPB1 gene was amplified and sequenced from Foc isolate FOC1708 and SK3-2. Regions specific for Foc were identified and used for designing real-time PCR primers. The specificity of the designed primers was evaluated on genomic DNA from Foc isolates and non-target microorganisms. The results showed that the designed primers were specific to only Foc isolates from race 1 and tropical race 4 (TR4). The detection efficiency of the designed primers was compared to other published primers through optimized SYBR green-based real-time PCR assay and nested PCR. The new primers could detect the Foc genomic DNA at a minimum of 5 pg and target pathogen in a symptomless banana sucker. The specificity and sensitivity of the new primers were comparable to the published real-time PCR primers and the nested PCR assay. This developed assay with these novel primers can aid the disease quarantine for effective prevention and control of the Fusarium wilt of banana.

Alternaria guilanica sp. nov., a new fungal pathogen causing leaf spot and blight on eggplant in Iran

Eggplant (Solanum melongena L.) is an economically important solanaceous crop in Iran with fruits used for food and traditional medicine. Despite the importance of Alternaria leaf spot and blight disease of solanaceous crops which is commonly seen in the fields, our knowledge about the causal agents on eggplant is limited. In this study, a set of large-spored Alternaria isolates was recovered from eggplant with leaf spot and blight symptoms in Somehsara region, Guilan province, Iran. All recovered isolates shared conspicuous morphological characteristics e.g. production of large, solitary conidia with several transverse disto- and eusepta and long tapering filamentous beak resemble those seen in the members of Alternaria section Porri. Multi-locus phylogenetic analyses based on the internal transcribed spacer region of nrDNA (ITS-rDNA) and parts of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), second largest subunit of RNA Polymerase II (RPB2), translation elongation factor 1-alpha (TEF1-α) and Alternaria major allergen (Alt a 1) gene sequences provided further evidence supporting not only their exact placement in Alternaria sect. Porri, but also in a distinct lineage representing a new species. The new species was named, described and illustrated herein as Alternaria guilanica sp. nov.. The phylogenetic and morphological comaprisions of the new species with other closely related species were also provided. Pathogenicity test conducted for the new strains revealed that they were capable to induce disease symptoms on eggplant leaves under greenhouse conditions, and re-isolation of the inoculated isolates confirmed Koch’s postulates.

Chaetomium and Chaetomium-like Species from European Indoor Environments Include Dichotomopilus finlandicus sp. nov.

The genus Chaetomium is a frequently occurring fungal taxon world-wide. Chaetomium and Chaetomium-like species occur in indoor environments, where they can degrade cellulose-based building materials, thereby causing structural damage. Furthermore, several species of this genus may also cause adverse effects on human health. The aims of this research were to identify Chaetomium and Chaetomium-like strains isolated from indoor environments in Hungary and Finland, two geographically distant regions of Europe with drier and wetter continental climates, respectively, and to study their morphological and physiological properties, as well as their extracellular enzyme activities, thereby comparing the Chaetomium and Chaetomium-like species isolated from these two different regions of Europe and their properties. Chaetomium and Chaetomium-like strains were isolated from flats and offices in Hungary, as well as from schools, flats, and offices in Finland. Fragments of the translation elongation factor 1α (tef1α), the second largest subunit of RNA polymerase II (rpb2) and β-tubulin (tub2) genes, as well as the internal transcribed spacer (ITS) region of the ribosomal RNA gene cluster were sequenced, and phylogenetic analysis of the sequences performed. Morphological examinations were performed by stereomicroscopy and scanning electron microscopy. Thirty-one Chaetomium sp. strains (15 from Hungary and 16 from Finland) were examined during the study. The most abundant species was Ch. globosum in both countries. In Hungary, 13 strains were identified as Ch. globosum, 1 as Ch. cochliodes, and 1 as Ch. interruptum. In Finland, 10 strains were Ch. globosum, 2 strains were Ch. cochliodes, 2 were Ch. rectangulare, and 2 isolates (SZMC 26527, SZMC 26529) proved to be representatives of a yet undescribed phylogenetic species from the closely related genus Dichotomopilus, which we formally describe here as the new species Dichotomopilus finlandicus. Growth of the isolates was examined at different temperatures (4, 15, 20, 25, 30, 37, 35, 40, and 45 °C), while their extracellular enzyme production was determined spectrophotometrically.

Phylogenetic, Morphological, and Pathogenic Characterization of Alternaria Species Associated With Fruit Rot of Mandarin in California.

Alternaria rot caused by Alternaria species is one of the major postharvest diseases of mandarin fruit in California. The aims of this study were to identify these Alternaria species via phylogenetic analyses and morphological characteristics and test their pathogenicity on mandarin. Decayed mandarin fruits exhibiting Alternaria rot symptoms were collected from three citrus fruit packinghouses in the Central Valley of California. In total, 177 Alternaria isolates were obtained from decayed fruit and preliminarily separated into three groups representing three species (A. alternata, A. tenuissima, and A. arborescens) based on the colony characterization and sporulation patterns. To further identify these isolates, phylogenetic analysis was conducted based on DNA sequences of the second largest subunit of RNA polymerase II (RPB2), plasma membrane ATPase (ATPase), and Calmodulin gene regions in combination with morphological characters. Of the 177 isolates, 124 (70.1%) were identified as A. alternata, and 53 (29.9%) were A. arborescens. The isolates initially identified as A. tenuissima based on the morphological characteristics could not be separated from those of A. alternata in phylogenetic analysis and thus considered A. alternata. Pathogenicity tests showed that both Alternaria species were pathogenic on mandarin fruit at both 5°C and 20°C. Our results indicated that two Alternaria species, A. alternata and A. arborescens, were responsible for Alternaria rot of mandarin fruit in California, with A. arborescens causing fruit rot on mandarin being reported for the first time.

First Report of Southern Blight on Polygonatum sibiricum Caused by Sclerotium delphinii in China.

Polygonatum sibiricum Delar. ex Redoute is a plant species used for medicine and food. On one hand, its rhizomes have potential medicinal values such as enhancing immunity, anti-aging, anti-tumor and antibacterial as well as the effects of improving memory and reducing blood lipid and sugar. On the other hand, the rhizomes can also be used as raw materials for drinks, preserves, and health products (Su et al. 2018). The annual demand of P. sibiricum is about 3500-4000 tons in China, and the market demands and the price continue to rise in recent years (Su et al. 2018). In August 2019, there was an outbreak of southern blight in the P. sibiricum planting fields (N30°04'06″, E115°39'47″) of Luotian County in Hubei province of China. Approximately 30% of plants were affected in many fields (333.33 ha). We observed that the surface of the infected rhizome and the surrounding soils were covered with white hyphae and sclerotia. The hyphae gradually extended downward to the rhizomes, causing rhizome rot and leaf yellowing and wilting. Mycelial fragments and sclerotia from ten symptomatic rhizomes were collected in the fields and incubated directly on potato dextrose agar (PDA containing 50 µg/ml kanamycin) at 27℃. The fungal colonies were transferred to PDA after two days of cultivation. The white colonies were formed with fluffy aerial mycelia, which grew radially with an average growth rate of 20.54±0.52 mm/d (n=10). The color of the sclerotia was milky white at first, and then gradually turned to beige and yellow-brown. After two-week-incubation, the sclerotia became dark brown. Most of the sclerotia were spherical or nearly spherical, with round-bulges on the surface. The number of mature sclerotia produced per plate ranged from 8-23 (n=10), and the size ranged from 2.5×3.0 mm to 7.5×13.0 mm (5.95 ± 2.34×7.51 ± 2.88 mm; n=50). In addition, clamp connections were observed under the microscope. For molecular identification, genomic DNA was extracted from isolate HJ-1 using the CTAB method (Mahadevakumar et al. 2018). The internal transcribed spacer (ITS) regions of rDNA were amplified with the primers ITS1/ITS4 (White et al. 1990). The resulting showed ITS sequence (Accession number: MW049362) was 99.66% homology with Sclerotium delphinii according to the GenBank database. In addition, the second largest subunit of RNA polymerase II gene (RBP2) and part of the elongation factor 1-alpha (EF1-α) gene were amplified by using the primers RPB26F/RPB2-7CR (Liu et al. 1999) and EF595F/EF1160R, respectively (Wendland and Kothe 1997). RPB2 gene sequence was deposited in GenBank (Accession number: MW415935), and was 99.53% similarity identity to Athelia rolfsii isolate MSB5-1. TEF-1α sequence was deposited in GenBank (Accession number: MW415934), and was 91.35% similarity to S. delphinii strain Sd_405. Because there are very few reference sequences of RPB2 genes from S. delphinii in GenBank to compare, we choose the ITS and TEF-1α gene sequences to construct the concatenated phylogenetic tree by the neighbor-joining method (Tamura et al. 2013). The results showed that HJ-1 was clustered with S. delphinii isolates selected from NCBI database. Based on morphological and molecular characteristics, the fungus was identified as S. delphinii Welch (teleomorph Athelia rolfsii (Curzi) C.C. Tu & Kimbr). Pathogenicity tests were performed on the healthy leaves, roots, stems and plants (n=3) of P. sibiricum. Each sample was inoculated with one sclerotia produced from a fifteen-day-old colony and there was on wound treatment. These inoculated and control samples (treated with sterile water) were incubated in a moist chamber (25 ± 2 °C, RH 85%) (Mahadevakumar et al. 2018). Typical disease symptoms were apparent on leaves, stems, rhizomes and plants at 4, 6, 5 and 15 days post inoculation, respectively. Fulfilling Koch's postulates, the fungal pathogens were isolated and purified from the inoculated site and were reconfirmed as S. delphinii based on the morphological features. To the best of our knowledge, this is the first report of S. delphinii causing southern blight on P. sibiricum in China. S. delphinii has a wide host range worldwide and often causes crop yield reduction. This study will be helpful for the prevention and control of P. sibiricum southern blight in the future.

Two new brown rot polypores from tropical China.

Brown-rot fungi are types of fungi that selectively degrade cellulose and hemicellulose from wood and are perhaps the most important agents involved in the degradation of wood products and dead wood in forest ecosystem. Two new brown-rot species, collected from southern China, are nested within the clades of Fomitopsis sensu stricto and Oligoporus sensu stricto, respectively. Their positions are strongly supported in the Maximum Likelihood phylogenetic tree of the concatenated the internal transcribed spacer (ITS) regions, the large subunit of nuclear ribosomal RNA gene (nLSU), the small subunit of nuclear ribosomal RNA gene (nuSSU), the small subunit of mitochondrial rRNA gene (mtSSU), the largest subunit of RNA polymerase II (RPB1), the second largest subunit of RNA polymerase II (RPB2) and the translation elongation factor 1-α gene (TEF1) sequences. Fomitopsisbambusae, only found on bamboo, is characterised by its resupinate to effused-reflexed or pileate basidiocarps, small pores (6–9 per mm), the absence of cystidia, short cylindrical to oblong-ellipsoid basidiospores measuring 4.2–6.1 × 2–2.3 μm. Oligoporuspodocarpi is characterised by white to pale cream pore surface, round or sometimes angular pores (5–6 per mm), broadly ellipsoid to reniform basidiospores measuring 3.8–4.2 × 2–2.3 μm and growing on Podocarpus. Illustrated descriptions of these two novel species, Fomitopsisbambusae and Oligoporuspodocarpi, are provided.

DEF1: Much more than an RNA polymerase degradation factor

Degradation Factor 1 was discovered 20 years ago as a yeast protein copurifying with Rad26, a helicase involved in transcription-coupled DNA repair. It was subsequently shown to control the ubiquitylation and destruction of the large subunit of DNA damage-arrested RNA Polymerase II. Since that time, much has been learned about Def1′s role in polymerase destruction and new functions of the protein have been revealed. We now understand that Def1 is involved in more than just RNA polymerase II regulation. Most of its known functions are associated with maintaining chromosome and genomic integrity, but other exciting activities outside this realm have been suggested. Here we review this fascinating protein, describe its regulation and present a hypothesis that Def1 is a central coordinator of ubiquitin signaling pathways in cells.

Four new species in the Tremellafibulifera complex (Tremellales, Basidiomycota).

Samples of species close to Tremellafibulifera from China and Brazil are studied, and T.fibulifera is confirmed as a species complex including nine species. Five known species (T.cheejenii, T.fibulifera s.s., T. “neofibulifera”, T.lloydiae-candidae and T.olens) and four new species (T.australe, T.guangxiensis, T.latispora and T.subfibulifera) in the complex are recognized based on morphological characteristics, molecular evidence, and geographic distribution. Sequences of eight species of the complex were included in the phylogenetic analyses because T.olens lacks molecular data. The phylogenetic analyses were performed by a combined sequence dataset of the internal transcribed spacer (ITS) and the partial nuclear large subunit rDNA (nLSU), and a combined sequence dataset of the ITS, partial nLSU, the small subunit mitochondrial rRNA gene (mtSSU), the translation elongation factor 1-α (TEF1), the largest and second largest subunits of RNA polymerase II (RPB1 and RPB2). The eight species formed eight independent lineages with robust support in phylogenies based on both datasets. Illustrated description of the six species including Tremellafibulifera s.s., T. “neofibulifera” and four new species, and discussions with their related species, are provided. A table of the comparison of the important characteristics of nine species in the T.fibulifera complex and a key to the whitish species in Tremella s.s. are provided.

New taxa in Glomeromycota: Polonosporaceae fam. nov., Polonospora gen. nov., and P. polonica comb. nov.

Phylogenetic analyses of sequences of the nuc rDNA small subunit (18S), internal transcribed spacer (ITS1-5.8S-ITS2 = ITS), and large subunit (28S) region (= 18S-ITS-28S), as well as sequences of this region concatenated with sequences of the largest subunit of RNA polymerase II (RPB1) gene, proved that the species originally described as Acaulospora polonica (phylum Glomeromycota) represents a new genus and a new family of the ancient order Archaeosporales, here introduced into the Glomeromycota under the names Polonospora and Polonosporaceae, respectively. The phylogenetic analyses and BLASTn queries also indicated that the Polonosporaceae with P. polonica comb. nov. still contains several morphologically undescribed taxa at the ranks of genus and species, which have a worldwide distribution.

Novel species of Alternaria section Nimbya from Iran as revealed by morphological and molecular data

ABSTRACT In this study, the diversity of Alternaria species in section Nimbya associated with symptomatic plants in the Cyperaceae and Juncaceae families was assessed. Multilocus sequence analyses of the rDNA internal transcribed spacer (ITS) region and parts of Alternaria major allergen (Alt a 1), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), second largest subunit of RNA polymerase II (RPB2), and translation elongation factor 1-alpha (TEF1) genes revealed the presence of two previously known species, A. scirpivora and A. caricicola, and three new species, which are described here as A. cypericola, sp. nov., A. heyranica, sp. nov., and A. junci-acuti, sp. nov. These new species were characterized morphologically with respect to the dimensions of conidia, the number of pseudosepta in mature conidia, and the type of conidium apical beak. According to the results of phylogenetic analyses, the presence of long, filiform true beak is not a reliable morphological indicator for grouping species in sections Alternantherae and Nimbya and phylogenetic species recognition should be used. All identified species were described, illustrated, and their morphology and phylogenetic relationships with other species in Alternaria section Nimbya were discussed.

An Overview of 24 Years of Molecular Phylogenetic Studies in Phallales (Basidiomycota) With Notes on Systematics, Geographic Distribution, Lifestyle, and Edibility.

The order Phallales (Basidiomycota) is represented by gasteroid fungi with expanded and sequestrate basidiomata, known as stinkhorns and false truffles. In phalloids, the first DNA sequence was published in 1997, and after that, some studies aimed to resolve phylogenetic conflicts and propose new species based on DNA markers; however, the number of families and genera in the order still generates controversies among researchers. Thus, this work aims to provide an overview of Phallales diversity represented by selected DNA markers available in public databases. We retrieved Phallales sequences from DNA databases (GenBank and UNITE) of seven markers: ITS (internal transcribed spacer), nuc-LSU (nuclear large subunit rDNA), nuc-SSU (nuclear small subunit rDNA), mt-SSU (mitochondrial small subunit rDNA), ATP6 (ATPase subunit 6), RPB2 (nuclear protein-coding second largest subunit of RNA polymerase), and TEF1-α (translation elongation factor subunit 1α). To compose our final dataset, all ITS sequences retrieved were subjected to BLASTn searches to identify additional ITS sequences not classified as Phallales. Phylogenetic analyses based on Bayesian and maximum likelihood approaches using single and combined markers were conducted. All ITS sequences were clustered with a cutoff of 98% in order to maximize the number of species hypotheses. The geographic origin of sequences was retrieved, as well as additional information on species lifestyle and edibility. We obtained a total of 1,149 sequences, representing 664 individuals. Sequences of 41 individuals were unidentified at genus level and were assigned to five distinct families. We recognize seven families and 22 genera in Phallales, although the delimitation of some genera must be further revisited in order to recognize only monophyletic groups. Many inconsistencies in species identification are discussed, and the positioning of genera in each family is shown. The clustering revealed 118 species hypotheses, meaning that approximately 20% of all described species in Phallales have DNA sequences available. Information related to geographic distribution represents 462 individuals distributed in 46 countries on all continents, except Antarctica. Most genera are saprotrophic with only one putative ectomycorrhizal genus, and 2.1% of the legitimate specific names recognized in Phallales are confirmed edible species. Great progress in the molecular analyses of phalloids has already been made over these years, but it is still necessary to solve some taxonomic inconsistencies, mainly at genus level, and generate new data to expand knowledge of the group.

G-Quadruplex in Gene Encoding Large Subunit of Plant RNA Polymerase II: A Billion-Year-Old Story.

G-quadruplexes have long been perceived as rare and physiologically unimportant nucleic acid structures. However, several studies have revealed their importance in molecular processes, suggesting their possible role in replication and gene expression regulation. Pathways involving G-quadruplexes are intensively studied, especially in the context of human diseases, while their involvement in gene expression regulation in plants remains largely unexplored. Here, we conducted a bioinformatic study and performed a complex circular dichroism measurement to identify a stable G-quadruplex in the gene RPB1, coding for the RNA polymerase II large subunit. We found that this G-quadruplex-forming locus is highly evolutionarily conserved amongst plants sensu lato (Archaeplastida) that share a common ancestor more than one billion years old. Finally, we discussed a new hypothesis regarding G-quadruplexes interacting with UV light in plants to potentially form an additional layer of the regulatory network.

Abstract 1269: Pharmacological targeting of transcription-replication conflict leads to anti-cancer efficacy with minimal side effects in preclinical models

Abstract Unchecked growth of cancer cells places simultaneous demands on DNA replication and transcription. Targeting the transcription-replication conflict (TRC), a major source of genome instability, could have important therapeutic implications. However, testing this hypothesis is difficult without agents directly targeting TRC. Here, we report a small molecule ligand (AOH1996) of the replisome component PCNA, which stabilizes interaction between PCNA and the large subunit (rpb1) of RNA polymerase II through the APIM motif, resulting in proteasome-dependent degradation of rpb1 and lethal DNA damages. Orally administrable, AOH1996 suppresses tumor growth without discernable toxicity at more than 10 time the compound's effective dose. In addition, AOH1996 works synergistically with known DNA damage agents to kill cancer cells. These results reveal TRC as cancer-selective vulnerability and demonstrated the therapeutic potential of AOH1996. Citation Format: Long Gu, Caroline Li, Robert Lingeman, Robert J. Hickey, Linda H. Malkas. Pharmacological targeting of transcription-replication conflict leads to anti-cancer efficacy with minimal side effects in preclinical models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1269.

Phylogeny and Mycotoxin Profile of Pathogenic Fusarium Species Isolated from Sudden Decline Syndrome and Leaf Wilt Symptoms on Date Palms (Phoenix dactylifera) in Tunisia.

In 2017–2018, extensive symptoms of sudden decline and fruit rot were observed on date palms in southern Tunisia. Samples of diseased plants were randomly collected in six localities. Based on morphological identification, Fusarium was the most frequent fungal genus detected. A sequencing of translation elongation factor, calmodulin, and second largest subunit of RNA polymerase II genes was used to identify 63 representative Fusarium strains at species level and investigate their phylogenetic relationships. The main species detected was Fusarium proliferatum, and at a much lesser extent, Fusarium brachygibbosum, Fusarium caatingaense, Fusarium clavum, Fusarium incarnatum, and Fusarium solani. Pathogenicity on the Deglet Nour variety plantlets and the capability to produce mycotoxins were also assessed. All Fusarium species were pathogenic complying Koch’s postulates. Fusarium proliferatum strains produced mainly fumonisins (FBs), beauvericin (BEA), and, to a lesser extent, enniatins (ENNs) and moniliformin (MON). All F. brachygibbosum strains produced low levels of BEA, diacetoxyscirpenol, and neosolaniol; two strains produced also T-2 toxin, and a single strain produced HT-2 toxin. Fusarium caatingaense, F. clavum, F. incarnatum produced only BEA. Fusarium solani strains produced MON, BEA, and ENNs. This work reports for the first time a comprehensive multidisciplinary study of Fusarium species on date palms, concerning both phytopathological and food safety issues.

Phylogenetic relationships in the genus Podoserpula and description of P. aliweni, a new species from Chile

ABSTRACT Phylogenetic analyses based on a three-locus nuclear data set (ITS1-5.8S-ITS2, the 5′ end of the 28S, and the largest subunit of RNA polymerase I) supported the pagoda fungus (Podoserpula, Amylocorticiales) as a monophyletic group most closely related to species of Anomoporia, which is nonmonophyletic, and Amyloathelia. Phylogenetic relationships inferred from internal transcribed spacer (ITS) sequences of specimens sampled in Australia, Chile, China, Madagascar, and New Zealand divided Podoserpula into two major lineages: Clade A containing Australian and New Zealand collections designated P. pusio and the Chinese species P. ailaoshanensis, which have basidiospores with no reaction to Melzer’s reagent, and Clade B, which includes a species described from Chile, P. aliweni, and specimens originating from Australia, Chile, Madagascar, and New Zealand with dextrinoid basidiospores. Podoserpula aliweni forms a unique branch in the phylogenetic tree and differs from its most closely related taxon by 1.8–2.1% in the ITS region. The new species exhibits a tree-like habit with a white to concolorous stipe-like base with the hymenophore’s main subcylindrical axis bearing up to 18 superimposed pilei, slightly enrolled white margins shading from yellowish white to orange-yellow toward the center, and ellipsoid to broadly ellipsoid basidiospores measuring 4.0–4.5 × 3.5 µm. Ecologically, P. aliweni occurs during the rainy season, often gregariously on dried branches or wet soil under Nothofagus dombeyi or N. obliqua and has a distribution range of more than 600 km in southern Chile. This study extends the known distributional range and increases our knowledge on the phylogenetic diversity and taxonomy in Podoserpula.

Molecular reassessment of diaporthalean fungi associated with strawberry, including the leaf blight fungus, Paraphomopsis obscurans gen. et comb. nov. (Melanconiellaceae)

ABSTRACTPhytopathogenic fungi in the order Diaporthales (Sordariomycetes) cause diseases on numerous economically important crops worldwide. In this study, we reassessed the diaporthalean species associated with prominent diseases of strawberry, namely leaf blight, leaf blotch, root rot and petiole blight, based on molecular data and morphological characters using fresh and herbarium collections. Combined analyses of four nuclear loci, 28S ribosomal DNA/large subunit rDNA (LSU), ribosomal internal transcribed spacers 1 and 2 with 5.8S ribosomal DNA (ITS), partial sequences of second largest subunit of RNA polymerase II (RPB2) and translation elongation factor 1-α (TEF1), were used to reconstruct a phylogeny for these pathogens. Results confirmed that the leaf blight pathogen formerly known as Phomopsis obscurans belongs in the family Melanconiellaceae and not with Diaporthe (syn. Phomopsis) or any other known genus in the order. A new genus Paraphomopsis is introduced herein with a new combination, Paraphomopsis obscurans, to accommodate the leaf blight fungus. Gnomoniopsis fragariae comb. nov. (Gnomoniaceae), is introduced to accommodate Gnomoniopsis fructicola, the cause of leaf blotch of strawberry. Both of the fungi causing leaf blight and leaf blotch were epitypified. Fresh collections and new molecular data were incorporated for Paragnomonia fragariae (Sydowiellaceae), which causes petiole blight and root rot of strawberry and is distinct from the above taxa. An updated multilocus phylogeny for the Diaporthales is provided with representatives of currently known families.

Gaeumannomyces nanograminis, sp. nov., a hyphopodiate fungus identified from diseased roots of ultradwarf bermudagrass in the United States

ABSTRACT The genus Gaeumannomyces (Magnaporthaceae, Magnaporthales, Sordariomycetes, Ascomycota) includes root-infecting pathogens, saprobes, and endophytes. Morphological, biological, and phylogenetic analyses were employed to identify fungal isolates derived from turfgrass roots colonized with ectotrophic, dark runner hyphae. Phylogenetic trees for partial sequences of the 18S nuc rDNA, ITS1-5.8S-ITS2 nuc rDNA internal transcribed spacer, and 28S nuc rDNA regions and of the minichromosome maintenance complex 7 (MCM7), largest subunit of RNA polymerase II (RPB1), and translation elongation factor 1-alpha (TEF1) genes were obtained via maximum likelihood and Bayesian methods. Our isolates consistently formed a distinct and highly supported clade within Gaeumannomyces. Common and distinctive biological and morphological characters reinforced these findings. Additionally, we conducted pathogenicity evaluations and demonstrated the ability of this fungus to colonize roots of ultradwarf bermudagrass (Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davey), its native host, via ectotrophic, dark runner hyphae, causing disease symptoms including root discoloration and reduced root and shoot mass. Altogether, our discoveries enabled recognition and description of a new species, Gaeumannomyces nanograminis, associated with rotted roots of ultradwarf bermudagrass.