Ecology


Publications (170)

Differential Expression of miRNAs Involved in Response to Candidatus Liberibacter asiaticus Infection in Mexican Lime at Early and Late Stages of Huanglongbing Disease

Citation
Bojórquez-Orozco et al. (2023). Plants 12 (5)
Names
Ca. Liberibacter asiaticus Liberibacter
Subjects
Ecology Ecology, Evolution, Behavior and Systematics Plant Science
Abstract
Huanglongbing (HLB) is one of the most destructive diseases threatening citriculture worldwide. This disease has been associated with α-proteobacteria species, namely Candidatus Liberibacter. Due to the unculturable nature of the causal agent, it has been difficult to mitigate the disease, and nowadays a cure is not available. MicroRNAs (miRNAs) are key regulators of gene expression, playing an essential role in abiotic and biotic stress in plants including antibacterial responses. However, knowledge derived from non-model systems including Candidatus Liberibacter asiaticus (CLas)-citrus pathosystem remains largely unknown. In this study, small RNA profiles from Mexican lime (Citrus aurantifolia) plants infected with CLas at asymptomatic and symptomatic stages were generated by sRNA-Seq, and miRNAs were obtained with ShortStack software. A total of 46 miRNAs, including 29 known miRNAs and 17 novel miRNAs, were identified in Mexican lime. Among them, six miRNAs were deregulated in the asymptomatic stage, highlighting the up regulation of two new miRNAs. Meanwhile, eight miRNAs were differentially expressed in the symptomatic stage of the disease. The target genes of miRNAs were related to protein modification, transcription factors, and enzyme-coding genes. Our results provide new insights into miRNA-mediated regulation in C. aurantifolia in response to CLas infection. This information will be useful to understand molecular mechanisms behind the defense and pathogenesis of HLB.

High Abundance of Candidatus Arthromitus in Intestinal Microbiota of Seriolella violacea (Palm Ruff) under Reared Conditions

Citation
Romero et al. (2023). Fishes 8 (2)
Names
Ca. Arthromitus
Subjects
Aquatic Science Ecology Ecology, Evolution, Behavior and Systematics
Abstract
Intestinal microbiota has been involved in several processes that benefit the host, such as digestion, nutrient metabolism, resistance to pathogens colonization and immune function. In this study, we investigated the diversity, composition and functional prediction of microbiota of reared Seriolella violacea (palm ruff) in the same cohort sampled at different times (7-, 8- and 9-month-old). Microbial community structure analyses, using 16S rRNA amplicon sequencing, revealed that the intestinal microbiota was dominated by the phyla Firmicutes, Proteobacteria, Fusobacteria and Tenericutes. At the genus level, Candidatus Arthromitus was the most abundant in all sampled timepoints, representing in average 78% of the bacterial community (ranging from 18 to 98%), corresponding to segmented filamentous bacteria, which are interesting because they have been associated with the maturation of immune responses in the gut and protecting the host from bacterial infections. The comparisons of the intestinal microbiota among the three groups showed differences in abundance of bacterial taxa and also in alpha diversity indexes (Shannon and Simpson), as well as beta diversity metrics (weighted and unweighted UniFrac). Potential functions of the intestinal microbiota of palm ruff were retrieved using Philipin and Tax4fun and these analyses revealed high levels of genes for sugar metabolism. To our knowledge, this study represents the first description of the intestinal microbiota of S. violacea.

Foliar Antibiotic Treatment Reduces <i>Candidatus</i> Liberibacter asiaticus Acquisition by the Asian Citrus Psyllid, <i>Diaphorina citri</i> (Hemiptera: Liviidae), but Does not Reduce Tree Infection Rate

Citation
Roldán et al. (2023). Journal of Economic Entomology 116 (1)
Names
Ca. Liberibacter asiaticus
Subjects
Ecology General Medicine Insect Science
Abstract
Abstract Huanglongbing (HLB), or citrus greening, is the most destructive disease of cultivated citrus worldwide. Candidatus Liberibacter asiaticus (CLas), the putative causal agent of HLB, is transmitted by the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae). In Florida, D. citri was first reported in 1998, and CLas was confirmed in 2005. Management of HLB relies on the use of insecticides to reduce vector populations. In 2016, antibiotics were approved to manage CLas infection in citrus. Diaphorina citri is host to several bacterial endosymbionts and reducing endosymbiont abundance is known to cause a corresponding reduction in host fitness. We hypothesized that applications of oxytetracycline and streptomycin would reduce: CLas populations in young and mature citrus trees, CLas acquisition by D. citri, and D. citri abundance. Our results indicate that treatment of citrus with oxytetracycline and streptomycin reduced acquisition of CLas by D. citri adults and emerging F1 nymphs as compared with that observed in trees treated only with insecticides, but not with antibiotics. However, under field conditions, neither antibiotic treatment frequency tested affected CLas infection of young or mature trees as compared with insecticide treatment alone (negative control); whereas trees enveloped with mesh screening that excluded vectors did prevent bacterial infection (positive control). Populations of D. citri were not consistently affected by antibiotic treatment under field conditions, as compared with an insecticide only comparison. Collectively, our results suggest that while foliar application of oxytetracycline and streptomycin to citrus reduces acquisition of CLas bacteria by the vector, even high frequency applications of these formulations under field conditions do not prevent or reduce tree infection.

Inoculation of Tomato With Plant Growth Promoting Rhizobacteria Affects the Tomato—Potato Psyllid—<i>Candidatus</i> Liberibacter Solanacearum Interactions

Citation
de Leon et al. (2023). Journal of Economic Entomology
Names
“Liberibacter solanacearum” Liberibacter
Subjects
Ecology General Medicine Insect Science
Abstract
Abstract The Rio Grande Valley (RGV) in southern Texas is well-suited for vegetable production due to its relatively mild/warm weather conditions in the fall and winter. Consequently, insects inflict year-round, persistent damage to crops in the RGV and regions with similar climate. Bactericera cockerelli (Šulc) (Hemiptera: Triozidae), commonly known as the potato psyllid, is a known vector of Candidatus Liberibacter solanacearum (CLso) (Hyphomicrobiales: Rhizobiaceae), a fastidious phloem-limited bacterium associated to vein-greening in tomatoes and Zebra Chip in potatoes. Vector control is the primary approach of integrated pest management (IPM) strategies that aim to prevent plant diseases in commercial agricultural systems. However, resistance-selective pressures that decrease the effectiveness of chemical control (insecticide) applications over time are of increasing concern. Therefore, we explore an ecological approach to devising alternative IPM methodologies to manage the psyllid-transmitted CLso pathogen to supplement existing chemical products and application schedules without increasing resistance. In this study, our objective was to examine the effects of plant-growth promoting rhizobacteria (PGPR) on host-vector-pathogen interactions. Soil-drench applications of PGPRs to Solanum lycopersicum (Solanales: Solanaceae) seedlings revealed structural and possible physiological changes to the plant host and indirect changes on psyllid behavior: host plants had increased length and biomass of roots and exhibited delayed colonization by CLso, while psyllids displayed changes in parental (F0) psyllid behavior (orientation and oviposition) in response to treated hosts and in the sex ratio of their progeny (F1). Based on our results, we suggest that PGPR may have practical use in commercial tomato production.

Genetic Diversity of “ <i>Candidatus</i> Liberibacter asiaticus” Based on Four Hypervariable Genomic Regions in China

Citation
Gao et al. (2022). Microbiology Spectrum 10 (6)
Names
Ca. Liberibacter asiaticus
Subjects
Cell Biology Ecology General Immunology and Microbiology Genetics Infectious Diseases Microbiology (medical) Physiology
Abstract
The hypervariable genomic regions derived from 35 published C Las genomes were used to decipher the genetic diversity of C Las strains and identify 10 new strains with high variations in prophage regions. Characterizing these variations in the C Las bacteria might provide insight into their evolution and adaptation to host plants and insects in China.

Occurrence, Diversity, and Genomes of “ <i>Candidatus</i> Patescibacteria” along the Early Diagenesis of Marine Sediments

Citation
Zhao et al. (2022). Applied and Environmental Microbiology 88 (24)
Names
Ca. Patescibacteria
Subjects
Applied Microbiology and Biotechnology Biotechnology Ecology Food Science
Abstract
Ultrasmall-celled “ Ca. Patescibacteria” have been estimated to account for one-quarter of the total microbial diversity on Earth, the parasitic lifestyle of which may exert a profound control on the overall microbial population size of the local ecosystems. However, their diversity and metabolic functions in marine sediments, one of the largest yet understudied ecosystems on Earth, remain virtually uncharacterized.

Characterization of a Pseudokeronopsis Strain (Ciliophora, Urostylida) and Its Bacterial Endosymbiont “Candidatus Trichorickettsia” (Alphaproteobacteria, Rickettsiales)

Citation
Castelli et al. (2022). Diversity 14 (12)
Names
Ca. Trichorickettsia mobilis Ca. Trichorickettsia
Subjects
Agricultural and Biological Sciences (miscellaneous) Ecological Modeling Ecology Nature and Landscape Conservation
Abstract
Symbiotic associations between bacteria and ciliate protists are rather common. In particular, several cases were reported involving bacteria of the alphaproteobacterial lineage Rickettsiales, but the diversity, features, and interactions in these associations are still poorly understood. In this work, we characterized a novel ciliate protist strain originating from Brazil and its associated Rickettsiales endosymbiont by means of live and ultrastructural observations, as well as molecular phylogeny. Though with few morphological peculiarities, the ciliate was found to be phylogenetically affiliated with Pseudokeronopsis erythrina, a euryhaline species, which is consistent with its origin from a lagoon with significant spatial and seasonal salinity variations. The bacterial symbiont was assigned to “Candidatus Trichorickettsia mobilis subsp. hyperinfectiva”, being the first documented case of a Rickettsiales associated with urostylid ciliates. It resided in the host cytoplasm and bore flagella, similarly to many, but not all, conspecifics in other host species. These findings highlight the ability of “Candidatus Trichorickettsia” to infect multiple distinct host species and underline the importance of further studies on this system, in particular on flagella and their regulation, from a functional and also an evolutionary perspective, considering the phylogenetic proximity with the well-studied and non-flagellated Rickettsia.

Mutual Exclusion of <i>Methanobrevibacter</i> Species in the Human Gut Microbiota Facilitates Directed Cultivation of a <i>Candidatus</i> Methanobrevibacter Intestini Representative

Citation
Low et al. (2022). Microbiology Spectrum 10 (4)
Names
Methanobrevibacter
Subjects
Cell Biology Ecology General Immunology and Microbiology Genetics Infectious Diseases Microbiology (medical) Physiology
Abstract
Methanogens are important hydrogen consumers in the gut and are associated with differing host health. Here, we determine the prevalence and abundance of archaeal species in the guts of a multi-ethnic cohort of healthy Singapore residents.

Dehalogenation of Chlorinated Ethenes to Ethene by a Novel Isolate, “ <i>Candidatus</i> Dehalogenimonas etheniformans”

Citation
Chen et al. (2022). Applied and Environmental Microbiology 88 (12)
Names
Ca. Dehalogenimonas etheniformans
Subjects
Applied Microbiology and Biotechnology Biotechnology Ecology Food Science
Abstract
Chlorinated ethenes are risk drivers at many contaminated sites, and current bioremediation efforts focus on organohalide-respiring Dehalococcoides mccartyi strains to achieve detoxification. We isolated and characterized the first non- Dehalococcoides bacterium, “ Candidatus Dehalogenimonas etheniformans” strain GP, capable of metabolic reductive dechlorination of TCE, all DCE isomers, and VC to environmentally benign ethene.