The Multifaceted Role of Homologous Recombination in a Fastidious Bacterial Plant Pathogen.

Homologous recombination plays a key function in the evolution of bacterial genomes. Within Xylella fastidiosa, an emerging plant pathogen with increasing host and geographic ranges, it has been suggested that homologous recombination facilitates host switching, speciation, and the development of virulence. We used 340 whole-genome sequences to study the relationship between inter- and intrasubspecific homologous recombination, random mutation, and natural selection across individual X.

Genie: an interactive real-time simulation for teaching genetic drift.

Neutral evolution is a fundamental concept in evolutionary biology but teaching this and other non-adaptive concepts is especially challenging. Here we present Genie, a browser-based educational tool that demonstrates population-genetic concepts such as genetic drift, population isolation, gene flow, and genetic mutation. Because it does not need to be downloaded and installed, Genie can scale to large groups of students and is useful for both in-person and online instruction.

Introduction and adaptation of an emerging pathogen to olive trees in Italy.

The invasive plant pathogen currently threatens European flora through the loss of economically and culturally important host plants. This emerging vector-borne bacterium, native to the Americas, causes several important diseases in a wide range of plants including crops, ornamentals, and trees. Previously absent from Europe, and considered a quarantine pathogen, was first detected in Apulia, Italy in 2013 associated with a devastating disease of olive trees (Olive Quick Decline Syndrome, OQDS).

Genetic differentiation of following the introduction into Taiwan.

The economically important plant pathogen has been reported in multiple regions of the globe during the last two decades, threatening a growing list of plants. Particularly, subspecies causes Pierce's disease (PD) of grapevines, which is a problem in the USA, Spain, and Taiwan. In this work, we studied PD-causing subsp.

Evidence of gene nucleotide composition favoring replication and growth in a fastidious plant pathogen.

Nucleotide composition (GC content) varies across bacteria species, genome regions, and specific genes. In Xylella fastidiosa, a vector-borne fastidious plant pathogen infecting multiple crops, GC content ranges between ∼51-52%; however, these values were gathered using limited genomic data. We evaluated GC content variations across X.

Allopatric Plant Pathogen Population Divergence following Disease Emergence.

Within the landscape of globally distributed pathogens, populations differentiate via both adaptive and nonadaptive forces. Individual populations are likely to show unique trends of genetic diversity, host-pathogen interaction, and ecological adaptation. In plant pathogens, allopatric divergence may occur particularly rapidly within simplified agricultural monoculture landscapes.

Impacts of local population history and ecology on the evolution of a globally dispersed pathogen.

Background: Pathogens with a global distribution face diverse biotic and abiotic conditions across populations. Moreover, the ecological and evolutionary history of each population is unique. Xylella fastidiosa is a xylem-dwelling bacterium infecting multiple plant hosts, often with detrimental effects.

Inference of Bacterial Pathogen Instantaneous Population Growth Dynamics.

Although bacterial host colonization is a dynamic process that requires population growth, studies often focus on comparing bacterial populations at a given time point. However, this may not reflect the dynamics of the colonization process. Time-course assays provide important insights into the dynamics of host colonization but are laborious and may still lack resolution for immediate processes affecting populations.

Draft Whole-Genome Sequences of Xylella fastidiosa subsp. fastidiosa Strains TPD3 and TPD4, Isolated from Grapevines in Hou-li, Taiwan.

We report the draft assemblies of TPD3 and TPD4, two subsp. isolates infecting grapevines in Hou-li, Taiwan. TPD3 and TPD4 showed similar characteristics regarding genome size (2,483,503 bp and 2,491,539 bp, respectively), GC content (51.

Emergence of a Plant Pathogen in Europe Associated with Multiple Intercontinental Introductions.

Pathogen introductions have led to numerous disease outbreaks in naive regions of the globe. The plant pathogen has been associated with various recent epidemics in Europe affecting agricultural crops, such as almond, grapevine, and olive, but also endemic species occurring in natural forest landscapes and ornamental plants. We compared whole-genome sequences of subspecies from America and strains associated with recent outbreaks in southern Europe to infer their likely origins and paths of introduction within and between the two continents.

Tail Wags the Dog? Functional Gene Classes Driving Genome-Wide GC Content in Plasmodium spp.

Plasmodium parasites are valuable models to understand how nucleotide composition affects mutation, diversification, and adaptation. No other observed eukaryotes have undergone such large changes in genomic Guanine-Cytosine (GC) content as seen in the genus Plasmodium (∼30% within 35-40 Myr). Although mutational biases are known to influence GC content in the human-infective Plasmodium vivax and Plasmodium falciparum; no study has addressed how different gene functional classes contribute to genus-wide compositional changes, or if Plasmodium GC content variation is driven by natural selection.

Evolution of the merozoite surface protein 7 (msp7) family in Plasmodium vivax and P. falciparum: A comparative approach.

Malaria parasites (genus Plasmodium) are a diverse group found in many species of vertebrate hosts. These parasites invade red blood cells in a complex process comprising several proteins, many encoded by multigene families, one of which is merozoite surface protein 7 (msp7). In the case of Plasmodium vivax, the most geographically widespread human-infecting species, differences in the number of paralogs within multigene families have been previously explained, at least in part, as potential adaptations to the human host.