A plastid phylogenomic framework for the palm family (Arecaceae).

BACKGROUND: Over the past decade, phylogenomics has greatly advanced our knowledge of angiosperm evolution. However, phylogenomic studies of large angiosperm families with complete species or genus-level sampling are still lacking. The palms, Arecaceae, are a large family with ca. 181 genera and 2600 species and are important components of tropical rainforests bearing great cultural and economic significance. Taxonomy and phylogeny of the family have been extensively investigated by a series of molecular phylogenetic studies in the last two decades. Nevertheless, some phylogenetic relationships within the family are not yet well-resolved, especially at the tribal and generic levels, with consequent impacts for downstream research. RESULTS: Plastomes of 182 palm species representing 111 genera were newly sequenced. Combining these with previously published plastid DNA data, we were able to sample 98% of palm genera and conduct a plastid phylogenomic investigation of the family. Maximum likelihood analyses yielded a robustly supported phylogenetic hypothesis. Phylogenetic relationships among all five palm subfamilies and 28 tribes were well-resolved, and most inter-generic phylogenetic relationships were also resolved with strong support. CONCLUSIONS: The inclusion of nearly complete generic-level sampling coupled with nearly complete plastid genomes strengthened our understanding of plastid-based relationships of the palms. This comprehensive plastid genome dataset complements a growing body of nuclear genomic data. Together, these datasets form a novel phylogenomic baseline for the palms and an increasingly robust framework for future comparative biological studies of this exceptionally important plant family.

The megaherbivore gap after the non-avian dinosaur extinctions modified trait evolution and diversification of tropical palms.

The Cretaceous-Palaeogene (K-Pg) extinction of the non-avian dinosaurs (66 Ma) led to a 25 million year gap of megaherbivores (>1000 kg) before the evolution of megaherbivorous mammals in the Late Eocene (40 Ma). The botanical consequences of this 'Palaeocene megaherbivore gap' (PMHG) remain poorly explored. We hypothesize that the absence of megaherbivores should result in changes in the diversification and trait evolution of associated plant lineages. We used phylogenetic time- and trait-dependent diversification models with palms (Arecaceae) and show that the PMHG was characterized by speciation slowdowns, decreased evolution of armature and increased evolution of megafaunal (≥4 cm) fruits. This suggests that the absence of browsing by megaherbivores during the PMHG may have led to a loss of defence traits, but the absence of megaherbivorous seed dispersers did not lead to a loss of megafaunal fruits. Instead, increases in PMHG fruit sizes may be explained by simultaneously rising temperatures, rainforest expansion, and the subsequent radiation of seed-dispersing birds and mammals. We show that the profound impact of the PMHG on plant diversification can be detected even with the overwriting of adaptations by the subsequent Late Eocene opening up of megaherbivore-associated ecological opportunities. Our study provides a quantitative, comparative framework to assess diversification and adaptation during one of the most enigmatic periods in angiosperm history.

Resolving taxonomic confusion: establishing the genus Phytobacter on the list of clinically relevant Enterobacteriaceae.

Although many clinically significant strains belonging to the family Enterobacteriaceae fall into a restricted number of genera and species, there is still a substantial number of isolates that elude this classification and for which proper identification remains challenging. With the current improvements in the field of genomics, it is not only possible to generate high-quality data to accurately identify individual nosocomial isolates at the species level and understand their pathogenic potential but also to analyse retrospectively the genome sequence databases to identify past recurrences of a specific organism, particularly those originally published under an incorrect or outdated taxonomy. We propose a general use of this approach to classify further clinically relevant taxa, i.e., Phytobacter spp., that have so far gone unrecognised due to unsatisfactory identification procedures in clinical diagnostics. Here, we present a genomics and literature-based approach to establish the importance of the genus Phytobacter as a clinically relevant member of the Enterobacteriaceae family.

Natural Occurring Phenolic Derivatives from Mauritia flexuosa (Buriti) Stems and Their Potential Antibacterial Activity against Methicillin-Resistant Staphylococcus aureus (MRSA).

Mauritia flexuosa Linnaeus filius (buriti or aguage; Arecaceae) is a palm used by traditional medicine in Brazil to treat dysentery and diarrhea. Our group showed that the soluble dichloromethane (CH2 Cl2 ) fraction from EtOH extract from M. flexuosa stems inhibited the growth of methicillin-susceptible Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) and it is rich in phenolic compounds. This study aimed to isolate new phenolic compounds from CH2 Cl2 fraction from M. flexuosa stems with in vitro antibacterial activity. The crude CH2 Cl2 fraction was fractionated by gel permeation chromatography (GPC) followed by semi-preparative RP-HPLC. The antibacterial activity was evaluated using the broth microdilution method against MSSA (ATCC 29213) and MRSA (clinical isolate 155). All compounds were also tested against Gram-negative (Escherichia coli; ATCC 35218) bacteria and two fungi species (Candida albicans; ATCC 14053 and Trichophyton rubrum; ATCC MYA 4438). The chemical structures of isolated compounds were determined by analysis and comparison with literature data of their NMR and HRMS spectra and optical activity. The chemical investigation yielded seven aromatic compounds, of which four, (2S,15S)-2,15-dimethyl-2,15-dioxa-1,8(1,4)-dibenzenacyclotetradecaphane (1), (2S,5S)-1-(4-hydroxyphenyl)hexane-2,5-diol (3), bruguierol E (4), and buritin (5) were previously unreported and three are known compounds identified as 6-(4'-hydroxyphenyl) hexan-2-one (2), (+)-(2R,3R)-dihydrokaempferol (6), and (+)-(2R)-naringenin (7). Compounds 1 and 7 showed antibacterial activity against MRSA and MSSA with minimum inhibitory concentrations (MICs) of between 62.5 and 31.3 µg/mL, respectively. Our preliminary findings support that CH2 Cl2 fraction from buriti, a typical species of flooded areas of Brazilian savanna, and its aromatic phenolic compounds are active against MSSA and MRSA contributing with understanding about the traditional use of this species.

Arbuscular mycorrhizal fungi promote coexistence and niche divergence of sympatric palm species on a remote oceanic island.

Microbes can have profound effects on their hosts, driving natural selection, promoting speciation and determining species distributions. However, soil-dwelling microbes are rarely investigated as drivers of evolutionary change in plants. We used metabarcoding and experimental manipulation of soil microbiomes to investigate the impact of soil and root microbes in a well-known case of sympatric speciation, the Howea palms of Lord Howe Island (Australia). Whereas H. forsteriana can grow on both calcareous and volcanic soils, H. belmoreana is restricted to, but more successful on, volcanic soil, indicating a trade-off in adaptation to the two soil types. We suggest a novel explanation for this trade-off. Arbuscular mycorrhizal fungi (AMF) are significantly depleted in H. forsteriana on volcanic soil, relative to both H. belmoreana on volcanic soil and H. forsteriana on calcareous soil. This is mirrored by the results of survival experiments, where the sterilization of natural soil reduces Howea fitness in every soil-species combination except H. forsteriana on volcanic soil. Furthermore, AMF-associated genes exhibit evidence of divergent selection between Howea species. These results show a mechanism by which divergent adaptation can have knock-on effects on host-microbe interactions, thereby reducing interspecific competition and promoting the coexistence of plant sister species.

Green Extraction of Six Phenolic Compounds from Rattan (Calamoideae faberii) with Deep Eutectic Solvent by Homogenate-Assisted Vacuum-Cavitation Method.

A homogenate-assisted vacuum-cavitation extraction (HVE) method with a "green" solvent (a deep eutectic solvent, DES) was developed to extract phenolic compounds from rattan (Calamoideae faberii). In this study, the optimum molar ratio of choline chloride (ChCl) and ethylene glycol (EG) was 1:3, the optimum volume ratio of ChCl-EG:H2O was 6:4, the solid-liquid ratio of HVE was 1:15, and the extraction time of homogenate and vacuum-cavitation were 2.0 min and 25 min, respectively. Under the optimum parameters of HVE, the extraction yield of total phenolic content with ChCl-EG solution was 6.82 mg/g. The higher total phenolic content was detected in fruit tissues (seeds 81.24 ± 1.55 mg/g, episperm 43.21 ± 0.87 mg/g, and arillus 38.47 ± 0.74 mg/g), followed by in leaves (sheath 19.5 ± 0.38 mg/g and blade 17.81 ± 0.33 mg/g). In addition, the content of specific phenolic compounds in aqueous and DES extracts was determined. Chlorogenic acid was the most abundant phenol in most organs of the rattan plant. Gallic acid was mainly distributed in the arillus; protocatechuic acid was mainly distributed in the arillus, sheath, and blade; protocatechuic aldehyde was mainly distributed in the blade, seed, and sheath; (+)-catechins were mainly distributed in the episperm, seed, and sheath; and epigallocatechin gallate was mainly distributed in the blade. The recovery rates of gallic acid, protocatechuic acid, protocatechuic aldehyde, (+)-catechins, chlorogenic acid, and epigallocatechin gallate were 93.77%, 94.09%, 97.32%, 97.83%, 94.41%, and 92.47%, respectively, by AB-8 resin.

Endemic palm species shed light on habitat shifts and the assembly of the Cerrado and Restinga floras.

Species expansions into new habitats are often associated with physiological adaptations, for instance when rain forest lineages colonize dry habitats. Although such shifts have been documented for the Brazilian savanna (Cerrado), little is known about the biogeographic origin of species occupying an extreme South American habitat type, the coastal dunes (Restinga). We examined the formation of this poorly known, endangered habitat by reconstructing the evolutionary history of two endemic species. Due to the proposed recency and uniqueness of this habitat, we hypothesized that Restinga species of the palm genus Allagoptera to be recently evolved and to present derived morphological characters. To detect habit shifts in absolute time, we used one plastid and nine nuclear genes to reconstruct the phylogenetic and biogeographic history of Allagoptera. We used light microscopy and stable isotope analysis to explore whether morphological adaptations occurred concomitantly with habitat shifts. Phylogenetic relationships were well supported and we found ancestral lineages of Allagoptera to be widely distributed throughout habitats that are currently occupied by extant species. Over the last ca. 7Ma Allagoptera has shifted its preference to increasingly dry habitats. Coincident with the colonization of the Cerrado and Restinga, morphological adaptations also evolved, including subterranean stems that are fire-resistant and long underground stem and root systems that facilitate water access. We did not find differences in metabolic pathway or modifications to pollen morphology when compared to other palm lineages. Assuming that the evolutionary history of Allagoptera is indicative of the habitat in which it occurs, our results infer a recent origin for Cerrado species. Although little is known about the formation of the Restinga habitat, our results also suggest a longer history than currently proposed; with an origin of Restinga habitats dating back to the Late Pliocene.

Plastid genomes reveal support for deep phylogenetic relationships and extensive rate variation among palms and other commelinid monocots.

Despite progress based on multilocus, phylogenetic studies of the palms (order Arecales, family Arecaceae), uncertainty remains in resolution/support among major clades and for the placement of the palms among the commelinid monocots. Palms and related commelinids represent a classic case of substitution rate heterogeneity that has not been investigated in the genomic era. To address questions of relationships, support and rate variation among palms and commelinid relatives, 39 plastomes representing the palms and related family Dasypogonaceae were generated via genome skimming and integrated within a monocot-wide matrix for phylogenetic and molecular evolutionary analyses. Support was strong for 'deep' relationships among the commelinid orders, among the five palm subfamilies, and among tribes of the subfamily Coryphoideae. Additionally, there was extreme heterogeneity in the plastid substitution rates across the commelinid orders indicated by model based analyses, with c. 22 rate shifts, and significant departure from a global clock. To date, this study represents the most comprehensively sampled matrix of plastomes assembled for monocot angiosperms, providing genome-scale support for phylogenetic relationships of monocot angiosperms, and lays the phylogenetic groundwork for comparative analyses of the drivers and correlates of such drastic differences in substitution rates across a diverse and significant clade.

An all-evidence species-level supertree for the palms (Arecaceae).

Several attempts have been made to generate complete species-level phylogenies for large clades, enabling comprehensive analyses of ecological or evolutionary hypotheses at the species level. No such phylogeny has, however, been generated for any major plant group yet, but here we generate such a phylogeny for the palm family (Arecaceae). We do this using a novel Bayesian approach, estimating the validity of intra-generic taxonomic groupings as topological constraints to assist in placing species without genetic or morphological data. From these we implement those that are supported by genetic or morphological data for a given genus or for related genera. The intergeneric relationships in our new phylogeny are surprisingly different from earlier phylogenies in the placement of genera within tribes, but largely identical to previous findings in the deeper branches in the phylogeny, pointing to the need for incorporating phylogenetic uncertainty in analyses based on this phylogeny. Initial analyses of the new phylogeny suggest non-constancy in diversification rates over time within genera, with an apparent increase in diversification rate over time, but no evidence for any geographic variation in the magnitude of this increase. We hope that our study will stimulate further evolutionary or ecological studies using palms as study organisms as well as discussions of the optimal way to place the many species without genetic or morphological data.

Evolution of stamen number in Ptychospermatinae (Arecaceae): insights from a new molecular phylogeny of the subtribe.

The palm subtribe Ptychospermatinae (Arecaceae: Arecoideae) is naturally distributed in the South West Pacific area and contains 12 genera and around 60 species, including numerous popular ornamentals. Like many palms, Ptychospermatinae flowers are small, trimerous, unisexual and always grouped into inflorescences of various sizes. However they exhibit a wide diversity in stamen number (a few to several dozen or even hundreds) that is poorly understood from an evolutionary point of view. Although advances have been made in elucidating phylogenetic relationships within Ptychospermatinae, some relationships among and within genera still remain to be clarified. Here we used a combination of five nuclear markers (nrITS2, the conserved nuclear intron BRSC10 and three low copy genes, PRK, RPB2 and AGAMOUS) and three chloroplast markers (matK, ndhA and rps15-ycf1) to propose a new phylogenetic hypothesis for the subtribe. The combination of all these markers improved the resolution and robustness of phylogenetic relationships within the subtribe, allowing us to identify four major clades. This phylogenetic framework was used to examine the evolution of stamen number in the clade. The optimization of stamen number on the phylogeny highlighted the high level of interspecific variability, showing that the character is highly labile and raising questions about the evolutionary and functional significance of this lability.

Kneiffiella palmae: A non-Aspergillus fungal infection isolated from a pulmonary nodule in a child with chronic granulomatous disease.

We report the first known human case of Kneiffiella palmae in the medical literature. K. palmae was isolated from a pulmonary nodule in a 7-year-old male with chronic granulomatous disease. The mold was identified as K. palmae at a national reference laboratory, where 17 other human respiratory samples tested positive for K. palmae from 2013 to 2021. Optimal antimicrobial treatment is unknown, but azoles and amphotericin B demonstrated in vitro activity against each tested isolate.

Genome-wide comparative analysis of transposable elements in Palmae genomes.

Background: Transposable elements (TEs) are the largest component of the genetic material of most eukaryotes and can play roles in shaping genome architecture and regulating phenotypic variation; thus, understanding genome evolution is only possible if we comprehend the contributions of TEs. However, the quantitative and qualitative contributions of TEs can vary, even between closely related lineages. For palm species, in particular, the dynamics of the process through which TEs have differently shaped their genomes remains poorly understood because of a lack of comparative studies. Materials and methods: We conducted a genome-wide comparative analysis of palm TEs, focusing on identifying and classifying TEs using the draft assemblies of four palm species: Phoenix dactylifera, Cocos nucifera, Calamus simplicifolius, and Elaeis oleifera. Our TE library was generated using both de novo structure-based and homology-based methodologies. Results: The generated libraries revealed the TE component of each assembly, which varied from 41-81%. Class I retrotransposons covered 36-75% of these species' draft genome sequences and primarily consisted of LTR retroelements, while non-LTR elements covered about 0.56-2.31% of each assembly, mainly as LINEs. The least represented were Class DNA transposons, comprising 1.87-3.37%. Conclusion: The current study contributes to a detailed identification and characterization of transposable elements in Palmae draft genome assemblies.

New Antimicrobial Phenyl Alkenoic Acids Isolated from an Oil Palm Rhizosphere-Associated Actinomycete, Streptomyces palmae CMU-AB204T.

Basal stem rot (BSR), or Ganoderma rot disease, is the most serious disease associated with the oil palm plant of Southeast Asian countries. A basidiomycetous fungus, Ganoderma boninense, is the causative microbe of this disease. To control BSR in oil palm plantations, biological control agents are gaining attention as a major alternative to chemical fungicides. In the course of searching for effective actinomycetes as potential biological control agents for BSR, Streptomyces palmae CMU-AB204T was isolated from oil palm rhizosphere soil collected on the campus of Chiang Mai University. The culture broth of this strain showed significant antimicrobial activities against several bacteria and phytopathogenic fungi including G. boninense. Antifungal and antibacterial compounds were isolated by antimicrobial activity-guided purification using chromatographic methods. Their structures were elucidated by spectroscopic techniques, including Nuclear Magnetic Resonance (NMR), Mass Spectrometry (MS), Ultraviolet (UV), and Infrared (IR) analyses. The current study isolated new phenyl alkenoic acids 1-6 and three known compounds, anguinomycin A (7), leptomycin A (8), and actinopyrone A (9) as antimicrobial agents. Compounds 1 and 2 displayed broad antifungal activity, though they did not show antibacterial activity. Compounds 3 and 4 revealed a strong antibacterial activity against both Gram-positive and Gram-negative bacteria including the phytopathogenic strain Xanthomonas campestris pv. oryzae. Compounds 7-9 displayed antifungal activity against Ganoderma. Thus, the antifungal compounds obtained in this study may play a role in protecting oil palm plants from Ganoderma infection with the strain S. palmae CMU-AB204T.

Genome-wide characterization of simple sequence repeats in Palmae genomes.

BACKGROUND: Microsatellites or simple sequence repeats (SSRs) have become the most significant DNA marker technology used in genetic research. The availability of complete draft genomes for a number of Palmae species has made it possible to perform genome-wide analysis of SSRs in these species. Palm trees are tropical and subtropical plants with agricultural and economic importance due to the nutritional value of their fruit cultivars. OBJECTIVE: This is the first comprehensive study examining and comparing microsatellites in completely-sequenced draft genomes of Palmae species. METHODS: We identified and compared perfect SSRs with 1-6 bp nucleotide motifs to characterize microsatellites in Palmae species using PERF v0.2.5. We analyzed their relative abundance, relative density, and GC content in five palm species: Phoenix dactylifera, Cocos nucifera, Calamus simplicifolius, Elaeis oleifera, and Elaeis guineensis. RESULTS: A total of 118241, 328189, 450753, 176608, and 70694 SSRs were identified, respectively. The six repeat types were not evenly distributed across the five genomes. Mono- and dinucleotide SSRs were the most abundant, and GC content was highest in tri- and hexanucleotide SSRs. CONCLUSION: We envisage that this analysis would further substantiate more in-depth computational, biochemical, and molecular studies on the roles SSRs may play in the genome organization of the palm species. The current study contributes a detailed characterization of simple sequence repeats in palm genomes.

Zymobacter palmae pyruvate decarboxylase production process development: Cloning in Escherichia coli, fed-batch culture and purification.

Pyruvate decarboxylase (PDC) is responsible for the decarboxylation of pyruvate, producing acetaldehyde and carbon dioxide and is of high interest for industrial applications. PDC is a very powerful tool in the enzymatic synthesis of chiral amines by combining it with transaminases when alanine is used as amine donor. However, one of the main drawback that hampers its use in biocatalysis is its production and the downstream processing on scale. In this paper, a production process of PDC from Zymobacter palmae has been developed. The enzyme has been cloned and overexpressed in Escherichia coli. It is presented, for the first time, the evaluation of the production of recombinant PDC in a bench-scale bioreactor, applying a substrate-limiting fed-batch strategy which led to a volumetric productivity and a final PDC specific activity of 6942 U L-1h-1 and 3677 U gDCW-1 (dry cell weight). Finally, PDC was purified in fast protein liquid chromatography equipment by ion exchange chromatography. The developed purification process resulted in 100% purification yield and a purification factor of 3.8.

Does leaf anatomy aid in species identification of Butia (Arecaceae)?

Butia is a neotropical genus whose identification is based mostly on characters from external morphology, which are sometimes variable or inadequate for species differentiation. We aimed to verify if leaf anatomy of 18 Butia species brings new characters suitable for species identification and if it corroborates the phylogenetic relationship within the genus. Moreover, we propose an anatomical key to assist in species identification. Pinnae were collected and subjected to the usual techniques for light and scanning electron microscopies. The anatomical key was created with the aid of Xper2 software, based on the importance of characters to distinguish species according to the Jaccard index. All species have isobilateral mirrored mesophyll, amphistomatic leaves and secondary vascular bundles with sclerenchymatic sheath reinforcement connected to the hypodermis. Among the species studied, B. marmorii and B. matogrossensis showed exclusive characters. For the other species, up to five characters are sufficient for delimitation. Our anatomical key presents relevant characters that allow the identification of the recognized species of Butia. Reliable anatomical characters of easy observation, especially the raphides, are valuable in species distinction. Leaf anatomy, already used to support new taxa in related genera like Allagoptera and Syagrus, can also be useful to validate questionable Butia species and differentiate between similar species but do not reflect the proposed relationship between Butia species.

Bioactive compounds and health benefits of some palm species traditionally used in Africa and the Americas - A review.

ETHNOPHARMACOLOGICAL RELEVANCE: According to previous ethno-medicinal reviews, Cocos nucifera, Elaeis guineensis and Phoenix dactylifera are among the main palms which are often used on the American and African continents to treat infections, infestations and disorders in the digestive, respiratory, genito-urinary, dermal, endocrine, cardiovascular, muscular-skeletal, mental and neural systems, as well as neoplasms, dental issues and metabolic and nutritional disorders. In addition, one or more species of the wild genera Acrocomia, Areca, Astrocaryum, Attalea, Bactris, Borassus, Calamus, Chamaedorea, Chamaerops, Euterpe, Hyphaene, Mauritia, Oenocarpus and Syagrus have a high number of records of these ethno-medicinal uses. The most used parts of the palm tree are the fruits, followed by roots, seeds, leaves and flower sap. AIM OF THE STUDY: This review discusses the phytochemical composition and the pharmacological properties of these important ethno-medicinal palms, aiming to provide a contribution to future research prospects. MATERIALS AND METHODS: Significant information was compiled from an electronic search in widely used international scientific databases (Google Scholar, Science Direct, SciFinder, Web of Science, PubMed, Wiley on line Library, Scielo, ACS Publications), and additional information was obtained from dissertations, theses, books and other relevant websites. RESULTS: Palms, in general, are rich in oils, terpenoids and phenolic compounds. Fruits of many species are notable for their high content of healthy oils and fat-soluble bioactive compounds, mainly terpenoids, such as pigment carotenoids (and provitamin A), phytosterols, triterpene pentacyclics and tocols (and vitamin E), while other species stood out for their phenolic compounds derived from benzoic and cinnamic acids, along with flavan-3-ol, flavone, flavonol, and stilbene compounds or anthocyanin pigments. In addition to fruits, other parts of the plant such as seeds, leaves, palm heart, flowers and roots are also sources of many bioactive compounds. These compounds are linked to the ethno-medicinal use of many palms that improve human health against infections, infestations and disorders of human systems. CONCLUSIONS: Palms have provided bioactive samples that validate their effectiveness in traditional medicine. However, the intensive study of all palm species related to ethno-medicinal use is needed, along with selection of the most appropriate palm accessions, ripe stage of the fruit and /or part of the plant. Furthermore, the complete profiles of all phytochemicals, their effects on animal models and human subjects, and toxicological and clinical trials are suggested, which, added to the incorporation of improved technological processes, should represent a significant advance for the implementation of new opportunities with wide benefits for human health.

Bioactive halogenated dihydroisocoumarins produced by the endophytic fungus Lachnum palmae isolated from Przewalskia tangutica.

Guided by the UPLC-ESIMS profile, seven previously undescribed halogenated dihydroisocoumarins, palmaerones A-G, along with eleven known dihydroisocoumarins, were isolated from Lachnum palmae, an endophytic fungus from Przewalskia tangutica by exposure to a histone deacetylase inhibitor SAHA. Structures of the isolates were elucidated by analysis of their NMR, MS and optical rotation values. The antimicrobial, anti-inflammatory and cytotoxic activities of palmaerones A-G were evaluated. Palmaerones A-G showed antimicrobial activities against the strains (C. neoformans, Penicillium sp., C. albicans, B. subtilis and S. aureus), and palmaerone E exhibited potential antimicrobial activities against all the test strains with the MIC value in the range of 10-55 µg/mL. Palmaerones A and E exhibited moderate inhibitory effects on NO production in LPS-induced RAW 264.7 cells, with the IC50 values of 26.3 and 38.7 µM, respectively and no obvious toxicities were observed at 50 µM. Palmaerone E showed weak cytotoxicity against HepG2 with the IC50 value of 42.8 µM. This work provides an effective strategy for expanding natural product resource.

Pest categorisation of Palm lethal yellowing phytoplasmas.

The EFSA Panel on Plant Health performed a pest categorisation of Palm lethal yellowing phytoplasmas for the EU territory. This name is used to describe diseases that share the same succession of symptoms in palms that are caused by a number of strains of phytoplasma, for which efficient molecular detection assays are available. The pest is not known to occur in the EU and therefore does not meet one of the criteria for being a Union regulated non-quarantine pest. For 'Candidatus Phytoplasma palmae', the planthopper Haplaxius crudus, which is not known to be present in the EU, is the confirmed vector, but for the other strains, the vectors are unknown. The host range of the pest is restricted to Arecaceae species, in particular coconut. The pest is regulated on all known hosts in Annex IIAI of Directive 2000/29/EC. It could potentially enter the EU via plants for planting or through infected vectors. The phytoplasmas could become established in the EU as host plants are present. It is unknown whether arthropods present in the EU could be vectors. The potential impact of the pest if introduced into the EU is difficult to assess given this uncertainty but is estimated to be limited. The main knowledge gaps concern the status of potential vector insects in the EU; the possibility for seed transmission of the phytoplasmas; the origin and volume of the trade in palm seeds and plants for planting; the host status and susceptibility of many palm species grown in the EU and the potential new assignments of phytoplasmas to this categorisation that might have associated alternate hosts. Palm lethal yellowing phytoplasmas meet the criteria assessed by EFSA for consideration as Union quarantine pest.

Crystal structure of pyruvate decarboxylase from Zymobacter palmae.

Pyruvate decarboxylase (PDC; EC 4.1.1.1) is a thiamine pyrophosphate- and Mg(2+) ion-dependent enzyme that catalyses the non-oxidative decarboxylation of pyruvate to acetaldehyde and carbon dioxide. It is rare in bacteria, but is a key enzyme in homofermentative metabolism, where ethanol is the major product. Here, the previously unreported crystal structure of the bacterial pyruvate decarboxylase from Zymobacter palmae is presented. The crystals were shown to diffract to 2.15 Šresolution. They belonged to space group P21, with unit-cell parameters a = 204.56, b = 177.39, c = 244.55 Šand Rr.i.m. = 0.175 (0.714 in the highest resolution bin). The structure was solved by molecular replacement using PDB entry 2vbi as a model and the final R values were Rwork = 0.186 (0.271 in the highest resolution bin) and Rfree = 0.220 (0.300 in the highest resolution bin). Each of the six tetramers is a dimer of dimers, with each monomer sharing its thiamine pyrophosphate across the dimer interface, and some contain ethylene glycol mimicking the substrate pyruvate in the active site. Comparison with other bacterial PDCs shows a correlation of higher thermostability with greater tetramer interface area and number of interactions.