Publications

4467

AbstractThe Asian citrus psyllid, Diaphorina citri, is the primary vector of the HLB pathogen, Candidatus Liberibacter asiaticus (CLas). The acquisition of CLas shortens the developmental period of nymphs, accelerating the emergence into adulthood and thereby facilitating the spread of CLas. Cuticular proteins (CPs) are involved in insect emergence. In this study, we investigated the molecular mechanisms underlying CLas‐promoted emergence in D. citri via CP mediation. Here, a total of 159 CP genes were first identified in the D. citri genome. Chromosomal location analysis revealed an uneven distribution of these CP genes across the 13 D. citri chromosomes. Proteomic analysis identified 54 differentially expressed CPs during D. citri emergence, with 14 CPs exhibiting significant differential expression after CLas acquisition. Five key genes, Dc18aa‐1, Dc18aa‐2, DcCPR‐24, DcCPR‐38 and DcCPR‐58, were screened from the proteome and CLas acquisition. The silencing of these 5 genes through a modified feeding method significantly reduced the emergence rate and caused various abnormal phenotypes, indicating the crucial role that these genes play in D. citri emergence. This study provides a comprehensive overview of the role of CPs in D. citri and reveals that CLas can influence the emergence process of D. citri by regulating the expression of CPs. These key CPs may serve as potential targets for future research on controlling huanglongbing (HLB) transmission.

Rose is severely affected by phytoplasma diseases, causing significant loss in flower quality. A valid control strategy is not yet available for managing phytoplasma diseases in roses. The present study aimed to obtain phytoplasma-free rose plants using antibiotics. In this study, phytoplasma-associated rose cultivar ‘Dr. M. S. Randhawa’ exhibiting phyllody and flower malformation symptoms was used to study the effect of three antibiotics namely, oxytetracycline, streptomycin and erythromycin A at different concentrations (60 mg/L, 80 mg/L and 100 mg/L) for management of phytoplasma under in-vitro and in-vivo conditions. All concentrations of oxytetracycline effectively eliminated phytoplasma in both conditions. The absence of phytoplasma was confirmed by nested Polymerase Chain Reaction (PCR) analysis in all treated plants in-vivo and in-vitro at monthly intervals for up to three months. However, streptomycin and erythromycin A treatments failed to eliminate phytoplasma in both conditions, as indicated by positive PCR results. The findings of this study reveal that oxytetracycline at 60 mg/L was the most efficient in eliminating phytoplasma from infected rose plants under both in-vitro and in-vivo conditions.

Phylogenetic analysis of the genus Aureimonas, utilizing both 16S rRNA gene sequences and comprehensive whole-genome data, revealed its polyphyletic nature, necessitating a revision to accommodate phylogenetically distinct species. Based on established threshold values for genus demarcation – specifically, 16S rRNA gene similarity, Average Amino Acid Identity and Percentage of Conserved Proteins – a notably substantial divergence was observed within the genus Aureimonas, and the division of Aureimonas into four distinct genera is strongly supported. To address this, we propose the establishment of four new genera: Dennerimonas gen. nov., Mesocryomonas gen. nov., Rathsackimonas gen. nov. and Plantimonas gen. nov. These classifications accommodate species that are significantly divergent from the type species of Aureimonas, thereby more accurately reflecting their distinct evolutionary lineages. Additionally, Aureimonas glaciistagni is proposed to be reclassified within the genus Jiella as Jiella glaciistagni comb. nov. based on phylogenetic evidence indicating a closer evolutionary relationship to Jiella species than to other members of Aureimonas. Our analysis, which included assessments of 16S rRNA gene similarity, Average Nucleotide Identity, and digital DNA–DNA hybridization values exceeding species delineation thresholds, further supports the reclassification of Jeongeupella Jiang et al. 2024 as a later heterotypic synonym of Antarcticirhabdus Du et al. 2023.

Marine heterotrophic bacteria in coastal waters respond to the influx of carbon from natural and anthropogenic sources. We identified two nearly identical, (99.9% average nucleotide identity; 100% amino acid identity; same DNA G + C content of 52.3 mol%) high-quality (≥99% CheckM completeness and ≤ 1.3% contamination) draft metagenome-assembled genomes (MAGs; SJ0813 and SJ0972) from seawater microbiomes of a southern island of Singapore that is in a protected marine park. The MAGs were only assigned to the Cellvibrionaceae family according to Genome Taxonomy Database. Overall genome related indices to Pseudomaricurvus alkylphenolicus KU41GT as the closest phylogenetic relative revealed no more than 70.45% average nucleotide identity (ANIcutoff < 95%), below the 50% percentage of conserved proteins (POCPcutoff = 43.54%) for genera cutoff and low digital DNA–DNA hybridization values (DDH = 20.6 and 20.8%). The major respiratory quinone is predicted to be ubiquinone-9 from the annotation of 3-demethylubiquinone-9 3-methyltransferase (ubiG, K00568) involved in the last step of the ubiquinone biosynthesis pathway (M00117), which differed from the ubiquinone-8 utilized by known members of Cellvibrionaceae. Both MAGs contained a complete pathway for dissimilatory nitrate reduction to ammonia, which increases bioavailability of nitrogen in seawater. An identical choline dehydrogenase found in both MAGs have a low amino-acid identity (≤64.47%) compared to existing GMC family oxidoreductases, expanding on the diversity of this family of enzymes. The MAGs meet nearly all the minimum requirements but lack a 16S rRNA gene of sufficient length required for the proposed novel genus and species under SeqCode. Nevertheless, phylogenetic trees based on core-genome and RpoB as an alternative phylogenetic marker are congruent with the taxon standing as a monophyletic clade to other taxa of the order Cellvibrionales. Taken together, the MAGs (SJ0813 and SJ0972) represent an uncultured, undescribed genus and species in which we tentatively propose the name Candidatus Pelagadaptatus aseana gen. nov., sp. nov. and strain SJ0813TS (=BAABNI000000000.1TS) as type sequence. Phylogenetic inference from core-genome and RpoB phylogenetic trees placed Umboniibacter marinipuniceus KMM 3891T outside Cellvibrionaceae. We, therefore, propose the transfer of the genus Umboniibacter from the family Cellvibrionaceae to a new family Umboniibacteraceae according to the International Code of Nomenclature of Prokaryotes.

Abstract Many thermophiles that are abundant in high-temperature geothermal systems have never been cultivated and are poorly understood, including deeply branching Thermoproteota. Here, we describe the genome-guided cultivation of one such organism, Calditenuis ramacidaminiphagus, and show that it has evolved a heterotrophic metabolism focused on branched-chain amino acids (BCAAs). Initially, fluorescence in situ hybridization and nanoscale secondary ion mass spectrometry (FISH-nanoSIMS) showed that Cal. ramacidaminiphagus assimilated amino acids rapidly in casamino acid-amended enrichment cultures. Genome and metaproteome analyses showed a high abundance and expression of BCAA transporter genes, suggesting a BCAA-focused metabolism. This inference was supported by the subsequent enrichment of Cal. ramacidaminiphagus in BCAA-fed cultures, reaching 2.66×106 cells/mL and 48.7% of the community, whereas it was outcompeted when polar amino acids (PAAs) were included. Metabolic reconstruction and metaproteomics suggest that BCAAs are channeled into the mevalonate pathway for lipid biosynthesis and fuel ATP production through oxidative Stickland reactions and the TCA cycle, both coupled with aerobic respiration. Ancestral state reconstructions and phylogenetic analyses of 62 Caldarchaeales genomes revealed multiple horizontal transfers of BCAA transporters to the ancestor of the genus Calditenuis. Our study highlights the crucial role of BCAAs in the early evolution and niche of this genus, and suggests a high degree of resource partitioning even within low-diversity thermophilic communities.