Ribosomal Elongation Research Articles

A canker disease of apple caused by Cytospora parasitica recorded in China

SummaryA stem canker disease of apple that differs from previously reported canker diseases has been recorded in Xinjiang Uygur Autonomous Region in China. Eight Cytospora strains obtained from diseased apple trees and inoculated onto healthy apple tree branches resulted in the development of the same disease symptoms. This pathogen formed conceptacles, which were multilocular pycnidia with common walls and a single ostiole. Comprehensive analysis of three DNA sequence regions (internal transcribed spacer, large ribosomal subunit and transcription elongation factor) and morphological and cultural characteristics revealed that these strains were most similar to the fungus Cytospora parasitica. This is the first report of C. parasitica causing canker disease of apple in China.

MRNA‐Independent way to regulate translation elongation rate in eukaryotic cells

The question of what governs the translation elongation rate in eukaryotes has not yet been completely answered. Earlier, different availability of different tRNAs was considered as a main factor involved, however, recent data revealed that the elongation rate does not always depend on tRNA availability. Here, we offer another, codon-independent approach to explain specific tRNA-dependence of the elongation rate in eukaryotes. We hypothesize that the exit rate of eukaryotic translation elongation factor 1A (eEF1A)*GDP from the 80S ribosome depends on the protein affinity to specific aminoacyl-tRNA remaining on the ribosome after GTP hydrolysis. Subsequently, a slower dissociation of eEF1A*GDP from certain aminoacyl-tRNAs in the ribosome can negatively influence the ribosomal elongation rate in a tRNA-dependent and mRNA-independent way. The specific tRNA-dependent departure rate of eEF1A*GDP from the ribosome is suggested to be a novel factor contributing to the overall translation elongation control in eukaryotic cells. © 2018 IUBMB Life, 70(3):192-196, 2018.

Oxidative stress damages rRNA inside the ribosome and differentially affects the catalytic center.

Intracellular levels of reactive oxygen species (ROS) increase as a consequence of oxidative stress and represent a major source of damage to biomolecules. Due to its high cellular abundance RNA is more frequently the target for oxidative damage than DNA. Nevertheless the functional consequences of damage on stable RNA are poorly understood. Using a genome-wide approach, based on 8-oxo-guanosine immunoprecipitation, we present evidence that the most abundant non-coding RNA in a cell, the ribosomal RNA (rRNA), is target for oxidative nucleobase damage by ROS. Subjecting ribosomes to oxidative stress, we demonstrate that oxidized 23S rRNA inhibits the ribosome during protein biosynthesis. Placing single oxidized nucleobases at specific position within the ribosome's catalytic center by atomic mutagenesis resulted in markedly different functional outcomes. While some active site nucleobases tolerated oxidative damage well, oxidation at others had detrimental effects on protein synthesis by inhibiting different sub-steps of the ribosomal elongation cycle. Our data provide molecular insight into the biological consequences of RNA oxidation in one of the most central cellular enzymes and reveal mechanistic insight on the role of individual active site nucleobases during translation.

Morphological and molecular characterization of a new succulenticolous Physarum (Myxomycetes, Amoebozoa) with unique polygonal spores linked in chains

A new plasmodiocarpic and sporocarpic species of myxomycete in the genus Physarum is described and illustrated. This new species appeared on decayed leaves and remains of succulent plants (Agave, Opuntia, Yucca) growing in arid zones. It differs from all other species in the genus in having polyhedral spores linked in chains like a string of beads, a unique feature within all known myxomycetes. Apart from detailed morphological data, partial sequences of both the small-subunit ribosomal RNA and elongation factor 1-alpha genes, generated from four isolates collected in two distant regions, i.e., Mexico and Canary Islands, are also provided in this study. Combined evidence supports the identity of the specimens under study as a new species.

Abstracts of Presentations at the 2017 APS Annual Meeting.

Light leaf spot (LLS), caused by Pyrenopeziza brassicae, is an important disease of Brassica napus (canola and oilseed rape) and B. oleracea (vegetable brassicas) in Europe (EU) as well as New Zealand and Australia (Oceania, OC). LLS was first reported in North America (NA) on B. juncea, B. napus, and B. rapa in six counties in western Oregon in 2014; and on B. juncea cover crops and wild B. rapa in three counties in northwestern Washington in 2016. Multi-locus sequence analysis (ITS ribosomal DNA, beta-tubulin, and elongation factor 1-α sequences) and comparison of the mating type genes (MAT1-1 and MAT1-2) grouped isolates from the EU (n = 28) and OC (n = 4) with the P. brassicae type specimen, IMI 204290, whereas isolates from NA (n = 16) represented a novel genotype. Sexual compatibility of NA and EU strains of complementary MAT1-1 and MAT1-2 genotypes is being determined to assess if NA isolates represent a distinct evolutionary lineage or a cryptic sibling species. Fungicide resistance has been documented in some EU populations of P. brassicae, but none of the NA isolates possessed amino acid substitutions E198A and L240F in the beta-tubulin sequences that confer resistance to benzimidazole fungicides; comparison of these sequences for the NA isolates revealed 100% identity to wild type EU P. brassicae isolates and the closely related fungus Rhynchosporium commune; and 98 and 99% identities to Sclerotinia sclerotiorum and Venturia inaequalis, respectively.

Determination and production of antimicrobial compounds by Aspergillus clavatonanicus strain MJ31, an endophytic fungus from Mirabilis jalapa L. using UPLC-ESI-MS/MS and TD-GC-MS analysis.

Endophytic fungi associated with medicinal plants are reported as potent producers of diverse classes of secondary metabolites. In the present study, an endophytic fungi, Aspergillus clavatonanicus strain MJ31, exhibiting significant antimicrobial activity was isolated from roots of Mirabilis jalapa L., was identified by sequencing three nuclear genes i.e. internal transcribed spacers ribosomal RNA (ITS rRNA), 28S ribosomal RNA (28S rRNA) and translation elongation factor 1- alpha (EF 1α). Ethyl acetate extract of strain MJ31displayed significant antimicrobial potential against Bacillus subtilis, followed by Micrococccus luteus and Staphylococcus aureus with minimum inhibitory concentrations (MIC) of 0.078, 0.156 and 0.312 mg/ml respectively. In addition, the strain was evaluated for its ability to synthesize bioactive compounds by the amplification of polyketide synthase (PKS) and non ribosomal peptide synthetase (NRPS) genes. Further, seven antibiotics (miconazole, ketoconazole, fluconazole, ampicillin, streptomycin, chloramphenicol, and rifampicin) were detected and quantified using UPLC-ESI-MS/MS. Additionally, thermal desorption-gas chromatography mass spectrometry (TD-GC-MS) analysis of strain MJ31 showed the presence of 28 volatile compounds. This is the first report on A. clavatonanicus as an endophyte obtained from M. jalapa. We conclude that A. clavatonanicus strain MJ31 has prolific antimicrobial potential against both plant and human pathogens and can be exploited for the discovery of new antimicrobial compounds and could be an alternate source for the production of secondary metabolites.

Analysis of cell cycle parameters during the transition from unhindered growth to ribosomal and translational stress conditions.

Abrogation of ribosome synthesis (ribosomal stress) leads to cell cycle arrest. However, the immediate cell response to cessation of ribosome formation and the transition from normal cell proliferation to cell cycle arrest have not been characterized. Furthermore, there are conflicting conclusions about whether cells are arrested in G2/M or G1, and whether the cause is dismantling ribosomal assembly per se, or the ensuing decreased number of translating ribosomes. To address these questions, we have compared the time kinetics of key cell cycle parameters after inhibiting ribosome formation or function in Saccharomyces cerevisiae. Within one-to-two hours of repressing genes for individual ribosomal proteins or Translation Elongation factor 3, configurations of spindles, spindle pole bodies began changing. Actin began depolarizing within 4 hours. Thus the loss of ribosome formation and function is sensed immediately. After several hours no spindles or mitotic actin rings were visible, but membrane ingression was completed in most cells and Ace2 was localized to daughter cell nuclei demonstrating that the G1 stage was reached. Thus cell division was completed without the help of a contractile actin ring. Moreover, cell wall material held mother and daughter cells together resulting in delayed cell separation, suggesting that expression or function of daughter gluconases and chitinases is inhibited. Moreover, cell development changes in very similar ways in response to inhibition of ribosome formation and function, compatible with the notion that decreased translation capacity contributes to arresting the cell cycle after abrogation of ribosome biogenesis. Potential implications for the mechanisms of diseases caused by mutations in ribosomal genes (ribosomopathies) are discussed.

Competitive Ability of Maize Pollen Grains Requires Paralogous Serine Threonine Protein Kinases STK1 and STK2.

serine threonine kinase1 (stk1) and serine threonine kinase2 (stk2) are closely related maize paralogous genes predicted to encode serine/threonine protein kinases. Pollen mutated in stk1 or stk2 competes poorly with normal pollen, pointing to a defect in pollen tube germination or growth. Both genes are expressed in pollen, but not in most other tissues. In germination media, STK1 and STK2 fluorescent fusion proteins localize to the plasma membrane of the vegetative cell. RNA-seq experiments identified 534 differentially expressed genes in stk1 mutant pollen relative to wild type. Gene ontology (GO) molecular functional analysis uncovered several differentially expressed genes with putative ribosome initiation and elongation functions, suggesting that stk1 might affect ribosome function. Of the two paralogs, stk1 may play a more important role in pollen development than stk2, as stk2 mutations have a smaller pollen transmission effect. However, stk2 does act as an enhancer of stk1 because the double mutant combination is only infrequently pollen-transmitted in double heterozygotes. We conclude that the stk paralogs play an essential role in pollen development.

Development of a quantitative real-time PCR assay using SYBR Green for early detection and quantification of Austropuccinia psidii in Eucalyptus grandis

Commercial areas containing Eucalyptus plantations have expanded in recent years due to increased demands for pulp, paper and bioenergy. One of the threats that can reduce Eucalyptus production is the eucalyptus rust disease caused by Austropuccinia psidii, a biotrophic fungus that affects a broad range of Myrtaceae. An accurate diagnosis tool for the early detection of rust disease could be useful in breeding programs for selection of resistant plants against rust, in phytosanitary purposes or in rust epidemics studies. The aim of the present work was to develop a SYBR Green-based quantitative real-time PCR (qPCR) assay for the early detection and quantification of A. psidii in Eucalyptus grandis leaves. Three sets of primers based on the A. psidii ribosomal DNA intergenic space region (IGS), beta-tubulin and elongation factor genes were designed and evaluated. The assays using the IGS primer set resulted in the highest detection efficiency, detecting a lower limit of 0.5 pg of A. psidii DNA. Under artificial inoculation in plants, A. psidii was detected immediately after pathogen inoculation until 240 h post-inoculation using qPCR. In field validation of the method, A. psidii was detected using qPCR in naturally infected leaves with or without rust symptoms. This easy and fast method can be used for an efficient detection of A. psidii in E. grandis leaves. The implications of this tool for rust studies are discussed below.

Mistakes in translation: Reflections on mechanism.

Mistakes in translation of messenger RNA into protein are clearly a detriment to the recombinant production of pure proteins for biophysical study or the biopharmaceutical market. However, they may also provide insight into mechanistic details of the translation process. Mistakes often involve the substitution of an amino acid having an abundant codon for one having a rare codon, differing by substitution of a G base by an A base, as in the case of substitution of a lysine (AAA) for arginine (AGA). In these cases one expects the substitution frequency to depend on the relative abundances of the respective tRNAs, and thus, one might expect frequencies to be similar for all sites having the same rare codon. Here we demonstrate that, for the ADP-ribosylation factor from yeast expressed in E. coli, lysine for arginine substitutions frequencies are not the same at the 9 sites containing a rare arginine codon; mis-incorporation frequencies instead vary from less than 1 to 16%. We suggest that the context in which the codons occur (clustering of rare sites) may be responsible for the variation. The method employed to determine the frequency of mis-incorporation involves a novel mass spectrometric analysis of the products from the parallel expression of wild type and codon-optimized genes in 15N and 14N enriched media, respectively. The high sensitivity and low material requirements of the method make this a promising technology for the collection of data relevant to other mis-incorporations. The additional data could be of value in refining models for the ribosomal translation elongation process.

Identification of two new species and a sexual morph from the genus Pseudopestalotiopsis

The genus Pseudopestalotiopsis comprises only seven species: Ps. camelliae, Ps. cocos, Ps. ignota, Ps. indica, Ps. kubahensis, Ps. simitheae, and Ps. theae. While surveying Pseudopestalotiopsis in Vietnam during 2013 and in Myanmar during 2015, we found 19 strains, including two novel Pseudopestalotiopsis species, based on morphological and phylogenetic analyses of internal transcribed spacer of nuclear ribosomal RNA, β-tubulin, and translation elongation factor 1-alpha gene region data sets. These new species are named Pseudopestalotiopsis myanmarina and Ps. vietnamensis. Among 13 strains identified as Ps. myanmarina, seven produced sexual morphs with similar morphological characteristics to those of “Pestalosphaeria,” indicating that sexual morphs of Pseudopestalotiopsis and Pestalotiopsis are common. Among the asexual morphs, one strain of Pseudopestalotiopsis had conidia with three pale-pigmented median cells, which is the same character found in Pestalotiopsis. In this study, we distinguished Pseudopestalotiopsis based on molecular analyses, whereas the results were unclear according to the morphological analyses.

The link between adjacent codon pairs and mRNA stability

BackgroundEvidence in diverse organisms suggests that codon optimality is a major determinant of mRNA translation and degradation. Codon optimality is thought to act by modulating the efficiency of ribosome elongation. In Saccharomyces cerevisiae, a recent study has identified 17 adjacent codon pairs that mediate strong inhibition of translation elongation. However, relationships between the inhibitory codon pairs and other aspects of gene expression are unknown.ResultsTo gain insights into how the inhibitory codon pairs may affect aspects of gene expression, we utilized existing datasets to conduct genome-scale analyses in S. cerevisiae. Our analysis revealed the following points. First, the inhibitory codon pairs are significantly associated with faster mRNA decay. The association is not solely due to the content of nucleotides, individual codons, or dipeptides encoded by the inhibitory codon pairs. Second, the inhibitory codon pairs cannot fully explain the previously known relationship of codon optimality with mRNA stability, suggesting that optimality of individual codons and properties of adjacent codon pairs both contribute to gene regulation. Finally, although the inhibitory codon pairs are associated with slower mRNA synthesis and protein instability, the associations can be attributed to usage bias in individual codons.ConclusionsThis study suggests an association of inhibitory codon pairs with mRNA stability and thus another layer of complexity in the codon-mediated gene regulation.

When mRNA translation meets decay.

Messenger RNA (mRNA) translation and mRNA degradation are important determinants of protein output, and they are interconnected. Previously, it was thought that translation of an mRNA, as a rule, prevents its degradation. mRNA surveillance mechanisms, which degrade mRNAs as a consequence of their translation, were considered to be exceptions to this rule. Recently, however, it has become clear that many mRNAs are degraded co-translationally, and it has emerged that codon choice, by influencing the rate of ribosome elongation, affects the rate of mRNA decay. In this review, we discuss the links between translation and mRNA stability, with an emphasis on emerging data suggesting that codon optimality may regulate mRNA degradation.

Ophiostoma sugadairense, a new species in the Ophiostoma piceae complex associated with bark beetles infesting Japanese larch in Japan

A new species in the Ophiostoma piceae complex was isolated from bark beetles and beetle galleries infesting Japanese larch in Japan, and was described as Ophiostoma sugadairense. Phylogenetic analyses of the internal transcribed spacer of the nuclear ribosomal RNA genes region, partial β-tubulin, and elongation factor-1α genes revealed that O. sugadairense was clearly separated from other species of the O. piceae complex. The sexual morph of O. sugadairense morphologically resembled that of O. breviusculum, but the asexual morph was clearly distinguishable based on morphological characteristics of the synnemata, such as their color and shape. Mating compatibility tests indicated that there is some degree of reproductive isolation between O. sugadairense and O. piceae, O. breviusculum, and O. subalpinum.

Elongation factor P restricts Salmonella\u2019s growth by controlling translation of a Mg2+ transporter gene during infection

When a ribosome translates mRNA sequences, the ribosome often stalls at certain codons because it is hard to translate. Consecutive proline codons are such examples that induce ribosome stalling and elongation factor P (EF-P) is required for the stalled ribosome to continue translation at those consecutive proline codons. We found that EF-P is required for translation of the mgtB gene encoding a Mg2+ transporter in the mgtCBR virulence operon from the intracellular pathogen Salmonellaenterica serovar Typhimurium. Salmonella lacking EF-P decreases MgtB protein levels in a manner dependent on consecutive proline codons located in the mgtB coding region despite increasing transcription of the mgtCBR operon via the mgtP open reading frame in the leader RNA, resulting in an altered ratio between MgtC and MgtB proteins within the operon. Substitution of the consecutive proline codons to alanine codons eliminates EF-P-mediated control of the mgtB gene during infection and thus contributes to Salmonella’s survival inside macrophages where Salmonella experiences low levels of EF-P. This suggests that this pathogen utilizes a strategy to coordinate expression of virulence genes by an evolutionarily conserved translation factor.

The Population of Fusarium oxysporum f. sp. fragariae, Cause of Fusarium Wilt of Strawberry, in California.

The objectives of this study were to investigate the structure of the population of Fusarium oxysporum f. sp. fragariae in California and to evaluate methods for its detection. Fifty-nine isolates of F. oxysporum f. sp. fragariae were obtained from diseased strawberry plants and their identity was confirmed by pathogenicity testing. The full nuclear ribosomal intergenic spacer (IGS) and elongation factor 1-α gene (EF-1α) were amplified by polymerase chain reaction (PCR) and sequenced to elucidate phylogenetic relationships among isolates. IGS and EF-1α sequences revealed three main lineages, which corresponded to three somatic compatibility groups. Primers designed to detect F. oxysporum f. sp. fragariae in Japan amplified a 239-bp product from 55 of 59 California isolates of F. oxysporum f. sp. fragariae and from no nonpathogenic isolates of F. oxysporum. The sequence of this PCR product was identical to the sequence obtained from F. oxysporum f. sp. fragariae isolates in Japan. Intensive sampling at two locations in California showed results of tests based on PCR and somatic compatibility to be in agreement for 97% (257 of 264) of isolates tested. Our findings revealed considerable diversity in the California population of F. oxysporum f. sp. fragariae, and indications that horizontal gene transfer may have occurred.

A Possible Role of the Full-Length Nascent Protein in Post-Translational Ribosome Recycling.

Each cycle of translation initiation in bacterial cell requires free 50S and 30S ribosomal subunits originating from the post-translational dissociation of 70S ribosome from the previous cycle. Literature shows stable dissociation of 70S from model post-termination complexes by the concerted action of Ribosome Recycling Factor (RRF) and Elongation Factor G (EF-G) that interact with the rRNA bridge B2a/B2b joining 50S to 30S. In such experimental models, the role of full-length nascent protein was never considered seriously. We observed relatively slow release of full-length nascent protein from 50Sof post translation ribosome, and in that process, its toe prints on the rRNA in vivo and in in vitro translation with E.coli S30 extract. We reported earlier that a number of chemically unfolded proteins like bovine carbonic anhydrase (BCA), lactate dehydrogenase (LDH), malate dehydrogenase (MDH), lysozyme, ovalbumin etc., when added to free 70Sin lieu of the full length nascent proteins, also interact with identical RNA regions of the 23S rRNA. Interestingly the rRNA nucleotides that slow down release of the C-terminus of full-length unfolded protein were found in close proximity to the B2a/B2b bridge. It indicated a potentially important chemical reaction conserved throughout the evolution. Here we set out to probe that conserved role of unfolded protein conformation in splitting the free or post-termination 70S. How both the RRF-EFG dependent and the plausible nascent protein–EFG dependent ribosome recycling pathways might be relevant in bacteria is discussed here.

Bayesian Network Models of Multiple Myeloma: Drivers of High Risk and Durable Response

IntroductionMultiple Myeloma (MM)is characterizedby heterogeneous clinical outcomes to existing therapies, which reflects the diverse genetic and molecular properties of tumor clones among patients. This intra-clonal heterogeneity may affect distinct molecular pathways within individual patients, contributing to reduced treatment efficacy over time and eventual relapse.In this work we investigate this problem by applying Bayesian network inference to develop high-dimensional network models of MM based on the Interim Analysis 9 (IA9) CoMMpass trial dataset (NCT0145429), an effort by the Multiple Myeloma Research Foundation (MMRF) to collect longitudinal data of newly-diagnosed patients from the United States, Canada and Europe. We demonstrate that our approach finds a number of known drug targets and identifies potentially novel ones. These targets, in our simulations, affect a number of treatment efficacy outcomes.MethodsThe IA9 dataset encompasses 645 patients with complete clinical and molecular data. We created an integrated table of clinical and genomic data including RNAseqmeasurements, somatic copy numbers, single nucleotide variants, and structural variants, for a combined input table of 30426 variables by 645 patients. We performed causal modeling using REFS™ Bayesian causal inference engine, constrained only by a minimal set of biological considerations but otherwise entirely de novo. The objective of modeling is to discover the causal mechanisms among variables and, in particular, with respect to the outcomes, by means of a set of Bayesian network models that are consistent with the observed disease biology. Such a model ensemble captures uncertainty in inference and highlights similarities among the models, allowing us to distinguish confident predictions from incidental ones.We investigated our model ensemble by means of systematic perturbations to model variables while observing effects upon treatment outcomes within specific patient backgrounds.ResultsDrivers of High RiskHigh riskwas definedas having disease progression before 18 months. The model uncovered a pathway involved in cell cycle regulation that leads to high risk when overexpressed. Specifically, the model identified CDK1, PKMY1, MELK, and NEK2 as the top drivers of the probability of high risk. These genes are "actionable", having drugsbeing investigatedclinically in the context of MM or in other cancers.Drivers of Durable ResponseDurable responsewas definedas a treatment response that lasts over a year before disease progression. The model was able to identify several novel pathways that appear to drive the probability of a durable response: a pathway of ribosomal genes (RPL6, RPL23, RPL12), a pathway of translation elongation factor EEF1A1 and associated pseudogenes, and a pathway of regulatory noncoding genes MIR1302-9, RP11-946L20.4, RP11-346D14.1, and RP11-506N2.1. Not much is known regarding the connection of these genes to MM. However, the ubiquitin-proteasome pathway, which is central to ribosomal biogenesis, is a major drug target in MM.ConclusionsIn this work we have developed a causal model of MM. In-silico perturbations of the model uncovered known and novel causal mechanisms for relevant endpoints, including a pathway involved in cell cycle that leads to high risk when dysregulated; a pathway involving ribosomal proteins and translation elongation factors that drives durable response; and several novel noncoding regulatory genes that are relevant to various measures of response. Beyond generating novel targets of immediate biological interest, our work demonstrates the promise of large-scale de novo network inference to this and similar problems in the future. [Display omitted] [Display omitted] [Display omitted] DisclosuresGruber:GNS Healthcare: Employment. McBride:Instat: Employment. Runge:GNS Healthcare: Employment. Wuest:GNS Healthcare: Employment. Hadzi:GNS Healthcare: Employment. Lonial:BMS: Consultancy; Novartis: Consultancy; Celgene: Consultancy; Onyx: Consultancy; Merck: Consultancy; Janssen: Consultancy; Novartis: Consultancy; Millenium: Consultancy; Celgene: Consultancy; Janssen: Consultancy; BMS: Consultancy; Onyx: Consultancy. Khalil:GNS Healthcare: Employment. Hayete:GNS Healthcare: Employment.

First detection of Endogone ectomycorrhizas in natural oak forests.

The order Endogonales in Mucoromycotina, an early divergent lineage of fungi, includes ectomycorrhizal (EM) fungi. This order is therefore considered a key taxon for elucidation of the evolution of EM associations. Recent studies have revealed high diversity of EM lineages of Basidiomycota and Ascomycota; however, EM associations of Endogonales and its relatives remain largely unknown. In this study, EM root tips with a unique fungal sheath, with aseptate and highly branched hyphae of variable widths, were identified in Quercus acutissima and Quercus crispula forests in the temperate zone of Japan. The mycobionts were confirmed as Endogone sp., which were placed as a sister clade of Endogone pisiformis, based on phylogenetic analyses of the small and large subunits of the nuclear ribosomal RNA and elongation factor-1α genes. This is the first report of EM of Endogone in natural forests of the Northern Hemisphere and the first finding on Quercus.

Chemical Control of Black Scorch Disease on Date Palm Caused by the Fungal Pathogen Thielaviopsis punctulata in United Arab Emirates.

Date palm (Phoenix dactylifera L.) is one of the most important plants grown for its edible fruit. Palm diseases are among the major factors affecting its growth and productivity. In the United Arab Emirates (UAE), the causal agent of black scorch on date palm was found to be Thielaviopsis punctulata. The pathogen was isolated from all tissues of diseased trees affected by the virulent T. punctulata. Depending on the severity of the infection, symptoms included tissue necrosis, wilting, neck bending, death of terminal buds, and eventual plant mortality. This fungus, which was consistently isolated on potato dextrose agar from infected tissues, produced two types of conidia: the thick-walled aleuroconidia (chlamydospores) and phialoconidia (endoconidia). In addition, all target regions of 5.8S ribosomal RNA, 28S ribosomal DNA, β-tubulin, and transcription elongation factor 1-α genes of the pathogen were amplified using polymerase chain reaction. We also found that the fungicide Score inhibited the mycelial growth of T. punctulata both in vitro and in vivo. Altogether, the morphology of the fruiting structures, pathogenicity tests, and molecular identification confirmed that the causal agent of symptomatic tissues is T. punctulata. This is the first report of the black scorch disease and the fungus T. punctulata on date palm in the UAE.