Biology subjects

Studholme, D. J.

Publications and source records attributed to Studholme, D. J..

16 recordsLinked to original sources

bioRxiv2026

Environmental Drivers and Distribution of Pathogenic Vibrio Species in the Teign Estuary, UK

Climate-driven increases in sea surface temperature have been associated with the expansion of Vibrio species and a corresponding rise in vibriosis cases in both human populations and aquaculture systems. Coastal waters across the south of England are increasingly becoming suitable for the growth and establishment of both human- and aquaculture-associated Vibrio species, potentially increasing vulnerability to the types of infections and disease outbreaks already reported elsewhere in the world. In this study, we report the presence of a diverse and well-established Vibrio community within the Teign Estuary, (Southwest, UK), including the human-pathogenic species V. parahaemolyticus, V. cholerae (non-O1/non-O139), V. alginolyticus, and V. diabolicus, as well as the important aquaculture pathogens V. jasicida, V. aestuarianus, and V. anguillarum. We identified V. diabolicus, a species that was indistinguishable from V. alginolyticus using conventional biochemical identification methods and could only be accurately resolved by whole-genome sequencing and developed novel PCR targets to differentiate these species in the lab. Using the insect infection model Galleria mellonella, we demonstrate that environmental isolates of V. cholerae (non-O1/non-O139), V. parahaemolyticus, and V. alginolyticus possess virulence potential. We also investigated the effects of sewage effluent on the growth of Vibrio isolates from the Teign Estuary and found that sewage can preferentially promote the growth of Vibrio species. Furthermore, several Vibrio isolates were multidrug resistant and carried antimicrobial resistance genes, highlighting the potential role of environmental Vibrio populations in the Teign Estuary as reservoirs of antimicrobial resistance. Together, these findings demonstrate how rising sea surface temperatures and sewage pollution may influence the emergence, persistence, and public health and aquaculture significance of Vibrio species in UK coastal waters.

microbiology↗

bioRxiv2026

What makes a banana false? How the genome of Ethiopian orphan staple Ensete ventricosum differs from the banana A and B sub-genomes

BackgroundEnsete ventricosum, also known as the "tree against hunger" plays a key role in Ethiopian food security and farming systems, feeding more than 20 million people. Since domestication via clonal selection in the south-west Ethiopian highlands, todays diverse enset landraces contribute multiple benefits including food, fibre by-product, animal bedding and cattle fodder to farmers and local communities. Improved genomic resources for this highly drought-tolerant plant are essential to supplement the conventional clonal selection-based breeding programme and pave the way towards targeted breeding. ResultsWe sequenced the genome of enset landrace Mazia, which is partially resistant/tolerant to Xanthomonas wilt and predicted 38,940 protein-coding genes. The Mazia assembly (540.14 Mb) is more complete than the previously published genome assembly of landrace Bedadeti (451.28 Mb) and displayed 1.41% heterozygosity and 64.64% repetitive DNA content. Comparative analyses with the Bedadeti assembly and chromosome-level genome sequences of the two main banana progenitors (Musa acuminata, AA genome; Musa balbisiana, BB genome) unexpectedly revealed [~]25% of the Mazia genome is unique to enset. Gene Ontology (GO) and sequence similarity search analysis of enset-specific protein-coding genes identified distinct functional signatures that underpin the lifestyle, adaptation, and corm productive quality of enset, including functions related to DNA integration, carbohydrate metabolism, disease resistance and transcriptional regulation. In contrast, Musa-specific genes showed enrichment for defence response, protein phosphorylation and fruit development pathways. Focusing on the classical nucleotide binding site leucine rich repeat (NLR) disease resistance genes, we identified and characterised NLRs in enset and Musa species genomes, revealing a considerable expansion in the Musa acuminata genome. We also identified unique genes in enset and banana genomes whose functional and evolutionary roles are yet to be determined. ConclusionsHere, we report a de novo genome assembly for the enset (Ensete ventricosum) landrace Mazia and provide a high-quality annotation of both Mazia and the previously published assembly of the landrace Bedadeti. Collectively, these genomic resources provide a valuable foundation for comparative genomics within the Musaceae family and open new opportunities for the development of marker-assisted breeding strategies to accelerate the improvement of agronomically important traits in enset.

bioinformatics↗

bioRxiv2025

DiPPER2 - a user-friendly pipeline for picking and evaluating taxon-specific PCR primers

Rapid, specific and sensitive detection is essential for pathogenic microorganisms in contexts ranging from phytosanitary-regulated diseases in agriculture to sepsis management in a clinical setting. Well-established, cost-effective, genomic-sequence-based methods are replacing or complementing laborious, slow and costly culture-based diagnostics. These methods include: end-point PCR and quantitative real-time PCR (qPCR), as well as digital PCR (dPCR) and droplet digital PCR (ddPCR). All these methods require oligonucleotide primers whose nucleotide sequences confer high specificity and sensitivity for the intended target. The most challenging steps in designing these assays include finding genomic sequences that are unique to the target pathogen and absent from off-target organisms, as well as designing primers for those sequences. Here, we present user-friendly, reliable and comprehensive tool DiPPER2 (Diagnostic Primer Picking and Evaluation pipeline for Reproducibility and Reliability), which finds unique diagnostic targets, designs end-point or qPCR primers for them, evaluates the primers in silico for specificity and sensitivity, characterizes the diagnostic target and produces a comprehensive and intuitive report. The pipeline has been developed according to FAIR (findable, accessible, interoperable and reproducible) principles and allows for flexible adjustment of primer parameters. It designs primers compatible with qPCR-, dPCR- and ddPCR. DiPPER2 can also evaluate previously designed primer sequences in silico for specificity and sensitivity. We use Pseudomonas amygdali pv. morsprunorum as an example to show that a clade-based, phylogeny-informed approach to diagnostic primer design ensures effective target discovery and specificity.

bioinformatics↗

bioRxiv2025

Advancing RNAi-Based Strategies Against Downy Mildews: Insights Into dsRNA Uptake and Gene Silencing

Downy mildew (DMs) dieases are caused by destructive obligate pathogens with limited control options, posing a significant threat to global agriculture. RNA interference (RNAi) has emerged as a promising, environmentally sustainable strategy for disease management. In this study, we evaluated the efficacy of dsRNA-mediated RNAi in suppressing key biological functions in DM pathogens of Arabidopsis thaliana, pea and lettuce DM pathogens, Hyaloperonospora arabidopsidis (Hpa), Peronospora viciae f. sp. pisi (Pvp) and Bremia lactucae (Bl), respectively. We specifically targeted the cellulose synthase 3 (CesA3) and the beta tubulin (BTUB) genes. Silencing CesA3 impaired spore germination and infection across multiple species, while BTUB silencing reinforced the potential of dsRNA-mediated inhibition. Reduction in gene expression levels correlated well with the sporulation assays confirming the effectiveness of dsRNA-mediated gene silencing. We used dsRNAs that were chemically synthesized, in vitro transcribed (IVT) or produced in E. coli. We found that the length and concentration of these dsRNAs significantly affected uptake efficiency, spore germination, and sporulation, with higher concentrations enhancing inhibitory effects. Confocal microscopy using Cy-5-labelled short-synthesized dsRNA (SS-dsRNA) provided direct evidence of spore uptake, confirming the potential of SS-dsRNA for pathogen control. However, species-specific sequence variations influenced dsRNA efficacy, underscoring the importance of target sequence design. Multiplexed RNAi impacted silencing synergisticly, further reducing germination and sporulation in Hpa. Additionally, we demonstrated that SS-dsRNA-mediated gene silencing is sustained over time, with a significant reduction in gene expression level at 4, 7, 10 and 11dpi. This indicates the durability and efficacy of this approach. Taken together, these findings demonstrate the potential of dsRNA-mediated gene silencing as a precision tool for managing DM pathogens.

plant biology↗

bioRxiv2025

Non-target effects on the soil microbiome of a plant root exudate biocontrol for Fusarium wilt

Crop rotation and intercropping with Allium spp. (e.g. garlic, onion) are recognized as biological controls of Fusarium wilt in several crops. However, the non-target effects of this strategy on the soil microbiome are largely unknown. We evaluated the effect of cultivating Musa basjoo, Allium tuberosum (Chinese leek), and their co-cultivation on the rhizosphere and bulk soil microbiome under glasshouse conditions. We do not report the impact of Chinese leek on Foc abundances, as this has been previously reported. The bacterial and fungal communities in the rhizosphere and bulk soil varied depending on the plant type. The microbiomes of allium and bananas were consistently dissimilar, and the co-cultivation treatment contained constituent taxa from both. However, the effect of allium on soil community composition was outweighed by that of bananas in the co-cultivation scenario. Discriminative taxa for allium included members of the genera Sphingomonas, Microbacterium, Flavihumibacter, Brevundimonas, Pseudolabrys, Ramlibacter, Trichoderma, Mortierella and Fusarium. In the case of bananas, predominant biomarkers encompassed members of Rhizobacter, Noviherbaspirillum, Pseudarthrobacter, Aquabacterium, Pseudomonas, Tausonia and Humicola Biomarkers and predictions of functional gene abundances suggest that shifts in the soil microbiome induced by allium are correlated with increases in microorganisms exhibiting potential disease suppression and antibiotic or antifungal traits, whereas those in bananas are associated with plant-growth-promoting microorganisms. The biocontrol efficacy of allium co-cultivation may there involve shifts in the soil microbiome as well as direct impacts of root exudate chemistry on Fusarium plant pathogens.

ecology↗

bioRxiv2025

Pea-Saving Partners: Bacillus and Pseudomonas combat downy mildew in pea crops

Downy mildew (DM) is a destructive disease that significantly reduces the yield and quality of important pulses (legumes) and horticultural crops, particularly during humid and cool seasons. This disease is caused by obligate and host-specific oomycete pathogens. Controlling the pathogen is challenging due to its long-term survival as spores and its rapid mutation. Use of chemical pesticides has been the most effective method to control DM pathogens, but their environmental hazards are a global concern. Current research is focused on exploring the potential of microbial biological control agents (MBCA), particularly rhizobacteria strains of the genera Bacillus and Pseudomonas, which have shown suppression of plant pathogens. However, to date, no MBCA has been reported to be effective against DM pathogens in pulses. We investigated the effectiveness of Bacillus and Pseudomonas strains as potential biopesticides against the pea downy mildew pathogen Peronospora viciae f. sp. pisi (Pvp). In our study, in vitro bioassays showed 100% inhibition of Pvp spore germination compared to the control. In planta antagonism assays further demonstrated significant suppression (>80%) of Pvp sporulation in pea plants sprayed with strains of Bacillus velezensis or P. fluorescens or their filtrates. The drench application also showed significant effects where either a Pseudomonas or cold-adapted Bacillus strain was used. We observed a synergistic effect for the dual foliar application of the microbes compared to individual application (27.6 to 46.7% suppression). Furthermore, the results from the molecular biomass analysis were consistent with the results of the sporulation assays. This demonstrates the strong interactive and promotive benefits of using Bacillus and Pseudomonas as biocontrol agents Based on these results, we conclude that these MBCAs could be effective in combatting Pvp infections in the field.

plant biology↗

bioRxiv2024

DIAMOND2GO: A rapid Gene Ontology assignment and enrichment tool for functional genomics

DIAMOND2GO (D2GO) is a new toolset to rapidly assign Gene Ontology (GO) terms to genes or proteins based on sequence similarity searches. D2GO uses DIAMOND for alignment, which is 100 - 20,000 X faster than BLAST. D2GO leverages GO- terms already assigned to sequences in the NCBI non-redundant database to achieve rapid GO-term assignment on large sets of query sequences. In one test, 98% of the 130,184 predicted human proteins and splice variants were assigned GO-terms (>2 million in total) in < 13 minutes on a laptop computer. D2GO also features the ability to perform enrichment analysis between subsets of data, thereby allowing rapid assignment and detection of over-represented GO-terms in novel sets of sequences. D2GO is freely available under the MIT licence from https://github.com/rhysf/DIAMOND2GO

bioinformatics↗

bioRxiv2024

Synchronization of Circadian Clock Gene Expression in Arabidopsis and Hyaloperonospora arabidopsidis and its Impact on Host-Pathogen Interactions

Organisms across all kingdoms have an internal circadian clock running in 24h cycles. This clock affects a variety of processes, including innate immunity in plants. However, the role of pathogen circadian clocks had not been extensively explored. We previously showed that light can influence infection of the oomycete Hyaloperonospora arabidopsidis (Hpa, downy mildew disease) on its natural host Arabidopsis thaliana. Here, we identified Hpa orthologs of known circadian clock genes (CCGs) Drosophila TIMELESS (TIM) and Arabidopsis Sensitive to Red Light Reduced 1 (AtSRR1) genes. Expression of both HpaTIM and HpaSRR1 showed a circadian rhythm when Hpa was exposed to constant light. Contrastingly, these two genes were negatively regulated by constant dark exposure. Furthermore, the expression patterns of HpaTIM and HpaSRR1 correlate with those of AtCCA1 and AtLHY, indicating a synchronisation of biological clock genes between the host and the pathogen. In addition, screening mutants of Arabidopsis Clock Regulated Genes (AtCRGs) with three virulent Hpa isolates revealed that mutations in AtCRGs influenced HpaTIM and HpaSRR1 expression and Hpa development, indicating a functional link between the plant biological clock and virulence. Moreover, sporulation of Hpa was reduced by targeting HpaTIM and HpaSRR1 with short synthesized small interfering RNAs, indicating that the pathogen clock is also relevant to virulence. We propose that plant and pathogen clocks are synchronized during infection and that proper regulation of both clocks are genetically necessary for pathogen virulence.

plant biology↗

bioRxiv2023

Manipulating multi-level selection in a fungal entomopathogen reveals social conflicts and a method for improving biocontrol traits

Changes in parasite virulence are commonly expected to lead to trade-offs in other life history traits that can affect fitness. Understanding these trade-offs is particularly important if we want to manipulate the virulence of microbial biological control agents. Theoretically, selection across different spatial scales, i.e. between- and within-hosts, shapes these trade- offs. However, trade-offs are also dependent on parasite biology. Despite their applied importance the evolution of virulence in fungal parasites is poorly understood: virulence can be unstable in culture and commonly fails to increase in simple passage experiments. We hypothesized that manipulating selection intensity at different scales would reveal virulence trade-offs in a fungal pathogen of aphids, Akanthomyces muscarius. Starting with a genetically diverse stock we selected for infectivity, parasite yield or speed of kill by manipulating competition within and between hosts and between groups of hosts over 7 rounds of infection. We characterized ancestral and evolved lineages by whole genome sequencing and by measuring virulence, growth rate, sporulation and fitness. While several lineages showed increases in virulence, we saw none of the trade-offs commonly found in obligately-killing parasites. Phenotypically similar lineages within treatments often shared multiple single-nucleotide variants, indicating strong convergent evolution. The most dramatic phenotypic changes were in timing of sporulation and spore production in vitro. We found that early sporulation led to reduced competitive fitness but could increase yield of spores on media, a trade-off characteristic of social conflict. Notably, the selection regime with strongest between-group competition and lowest genetic diversity produced the most consistent shift to early sporulation, as predicted by social evolution theory. Mutli-level selection therefore revealed social interactions novel to fungi and showed that these biocontrol agents have the genomic flexibility to improve multiple traits -virulence and spore production - that are often in conflict in other parasites. Author summaryUnderstanding the ecological forces that shape virulence is a key challenge in evolutionary biology. Here we investigated how competition at different levels of selection (within-hosts, between-hosts, between populations) could alter investment in virulence in a fungal entomopathogen. We predicted that cooperative investment in virulence would increase at higher scales of competition and aimed to further our understanding of potential trade-offs shaping life-history of a fungal insect pathogens. We found moderate increases in virulence in different selection regimes but importantly, none of the commonly expected trade-offs, such as that between spore production and virulence or a relationship between virulence and growth rate, which is consistent with cooperation. However, we found convergent genetic changes and significant differences in timing and production of spores, dependent how we manipulated scales of selection. Our data suggests that this is driven by social conflict regarding the timing of sporulation. This carries fundamental importance for understanding how varying selection pressure at different scales shape pathogen life history. In addition, these results also have applied importance for understanding how to improve and select for beneficial traits in biocontrol agents.

evolutionary biology↗

bioRxiv2022

Genome sequence data reveal at least two distinct incursions of the tropical race 4 (TR4) variant of Fusarium wilt into South America

The global banana industry is threatened by one of the most devastating diseases: Fusarium wilt (FWB). FWB is caused by the soil-borne fungus Fusarium oxysporum f. sp. cubense (Foc), which almost annihilated the banana production in the late 1950s. A new strain of Foc, known as tropical race 4 (TR4), attacks a wide range of banana varieties including Cavendish clones which are the source of 99% of banana exports. In 2019, Foc TR4 was reported in Colombia, and more recently (2021) in Peru. In this study, we sequenced three fungal isolates identified as Foc TR4 from La Guajira (Colombia) and compared them against 19 whole-genome sequences of Foc TR4 publicly available, including four genome sequences recently released from Peru. To understand the genetic relatedness of the Colombian Foc TR4 isolates and those from Peru, we conducted a phylogenetic analysis based on a genome-wide set of single nucleotide polymorphisms (SNPs). Additionally, we compared the genomes of the 22 available Foc TR4 isolates looking for the presence-absence of gene polymorphisms and genomic regions. Our results reveal that (i) the Colombian and Peruvian isolates are genetically distant, which could be better explained by independent incursions of the pathogen to the continent, and (ii) there is a high correspondence between the genetic relatedness and geographic origin of Foc TR4. The profile of present/absent genes and the distribution of missing genomic regions showed a high correspondence to the clades recovered in the phylogenetic analysis, supporting the results obtained by SNP-based phylogeny.

genomics↗

bioRxiv2021

Two-speed genome expansion drives the evolution of pathogenicity in animal fungal pathogens

The origins of virulence in amphibian-infecting chytrids Batrachochytrium dendrobatidis (Bd) and Batrachochytrium salamandrivorans (Bsal) are largely unknown. Here, we use deep nanopore sequencing of Bsal and comparative genomics against 21 high-quality genome assemblies that span the fungal Chytridiomycota. Bsal has the most repeat-rich genome, comprising 40.9% repetitive elements, which has expanded to more than 3X the length of its conspecific Bd. M36 metalloprotease virulence factors are highly expanded in Bsal and 53% of the 177 unique genes are flanked by transposable elements, suggesting repeat-driven expansion. The largest M36 sub-family are mostly (84%) flanked upstream by a novel LINE element, a repeat superfamily implicated with gene copy number variations. We find that Bsal has a highly compartmentalized genome architecture, with virulence factors enriched in gene-sparse/repeat-rich compartments, while core conserved genes occur in gene-rich/repeat-poor compartments. This is a hallmark of two-speed genome evolution. Furthermore, genes with signatures of positive selection in Bd are enriched in repeat-rich regions, suggesting they are a cradle for chytrid pathogenicity evolution, and Bd also has a two-speed genome. This is the first evidence of two-speed genomes in any animal pathogen, and sheds new light on the evolution of fungal pathogens of vertebrates driving global declines and extinctions.

genomics↗

bioRxiv2020

Halophytic bacterial endophytome: a potential source of beneficial microbes for a sustainable agriculture

Halophytes have evolved several strategies to survive in saline environments; however, additional support from their associated microbiota could help combat adverse conditions. Endophytic communities of halophytes may be different than those in other plants because salinity acts as an environmental filter. At the same time, they may contribute to the hosts adaptation to adverse environmental conditions and can improve host tolerance against various biotic and abiotic stresses, which may be of importance in modern and sustainable agriculture. In this study the culturable endophytic bacteria of three halophytic species Cakile maritima, Matthiola tricuspidata and Crithmum maritimum were isolated and identified. Endophytic bacteria were isolated from roots and leaves of the sampled plants. Significant differences were observed in bacterial species abundance among different plant species and tissue from which the isolates were obtained. In total, 115 strains were identified by analysis of complete 16S rDNA sequences, while the majority of these isolates were derived from the root samples. The strains were evaluated for their ability to: 1) grow in-vitro in high levels of NaCl; 2) inhibit the growth of the economically important plant pathogenic fungus Verticillium dahliae in vitro and in planta, the human pathogenic fungus Aspergillus fumigatus in vitro, as well as, the economically important plant bacterial pathogens Ralstonia solanacearum and Clavibacter michiganensis in vitro; 3) provide salt tolerance in planta; 4) provide growth promoting effect in planta. Additionally, the genomes of twelve selected isolates, exhibiting interesting features, were sequenced and analysed. Three novel bacterial species were identified that belong to the genus Pseudomonas (two strains) and Arthrobacter (one strain). The outcome of our study is the proof-of-concept that the crop wild relatives (CWR) halophytic microbiome could potentially serve as a source of beneficial microorganisms that could be used (as unique species or as artificial communities) as Bio-Inoculants, for the enhancement of plant growth and stress tolerance in crops, including the high-salinity stress. This is very important in the era of ecosystem degradation and climate change, where the maximizing microbial functions in agroecosystems could be a prerequisite for the future of global sustainable agriculture. Globally, there is a strong need for the identification and bio-banking of novel beneficial endophytic microbes with as many desirable characters, for the development of a new environmentally friendly global strategy in food production that will be based in the sustainable agriculture with low chemical inputs and a low environmental impact.

microbiology↗

bioRxiv2019

Evaluation of 20 enset (Ensete ventricosum) landraces for response to Xanthomonas vasicola pv. musacearum infection

Bacterial wilt, caused by Xanthomonas vasicola pv. musacearum (Xvm), formerly X. campestris pv. musacearum, is the most threatening and economically important disease of enset (Ensete ventricosum), the multipurpose food security crop orphan to south and southwestern Ethiopia. Xvm has also had a major impact on banana and plantain production in East Africa following its detection in Uganda in 2001 and subsequent spread. Effective control of this disease currently relies on integrated disease management (IDM) strategies including minimization of field pathogen inoculum and deployment of wilt resistant enset landraces. Identifying landraces with stable and durable Xvm resistance will greatly accelerate breeding of varieties that can be included as a component of IDM. In this study, 20 enset landraces previously reported to exhibit lower susceptibility to Xvm were grown in pots under open field conditions and inoculated with an aggressive Xvm inoculum isolated from a disease hotspot area. Longitudinal and survival analyses were applied to each landrace, based on disease units representing a combination of area-under-disease progress stairs, disease index and apparent infection rate. Considerable variation was observed among the 20 landraces; however, none exhibited full immunity to Xvm infection. Three landraces, viz. Haela, Mazia and Lemat (HML), showed lowest susceptibility to Xvm as evidenced by lower disease units and higher survival rates. Landraces Kuro, Gezewet, Bededet, and Alagena showed similar levels of Xvm infection as did HML, but with lower survival rates. By contrast, landrace Arkia showed the highest infection level and lowest survival rate, suggesting a high degree of susceptibility to Xvm. This study identifies new material that can be used in future breeding programmes to develop Xvm-resistant enset varieties.

plant biology↗

bioRxiv2019

The Zymoseptoria tritici ORFeome: a functional genomics community resource

Libraries of protein-encoding sequences can be generated by identification of open reading frames (ORFs) from a genome of choice that are then assembled into collections of plasmids termed ORFeome libraries. These represent powerful resources to facilitate functional genomic characterization of genes and their encoded products. Here, we report the generation of an ORFeome for Zymoseptoria tritici, which causes the most serious disease of wheat in temperate regions of the world. We screened the genome of strain IP0323 for high confidence gene models, identifying 4075 candidates from 10,933 predicted genes. These were amplified from genomic DNA, cloned into the Gateway(R) Entry Vector pDONR207, and sequenced, providing a total of 3022 quality-controlled plasmids. The ORFeome includes genes predicted to encode effectors (n = 410) and secondary metabolite biosynthetic proteins (n = 171), in addition to genes residing at dispensable chromosomes (n= 122), or those that are preferentially expressed during plant infection (n = 527). The ORFeome plasmid library is compatible with our previously developed suite of Gateway(R) Destination vectors, which have various combinations of promoters, selection markers, and epitope tags. The Z. tritici ORFeome constitutes a powerful resource for functional genomics, and offers unparalleled opportunities to understand the biology of Z. tritici.

systems biology↗

bioRxiv2019

Transfer of Xanthomonas campestris pv. arecae, and Xanthomonas campestris pv. musacearum to Xanthomonas vasicola (Vauterin) as Xanthomonas vasicola pv. arecae comb. nov., and Xanthomonas vasicola pv. musacearum comb. nov. and description of Xanthomonas vasicola pv. vasculorum pv. nov.

LETTER TO THE EDITOR LETTER TO THE EDITOR EMENDED DESCRIPTION OF... REFERENCES Members of the genus Xanthomonas, within the gamma-Proteobacteria, collectively cause disease on more than 400 plant species (Hayward 1993), though some members are apparently non-pathogenic (Vauterin et al. 1996) and some have been isolated from clinical samples such as skin microbiota (Seite, Zelenkova, and Martin 2017). Historically, taxonomy of Xanthomonas was tied to the host of isolation (Starr 1981; Wernham 1948), with the genus being split into large numbers of species, each defined by this single phenotypic feature (Dye 1962). Subsequently, most of the species were transferred (lumped) into a single species, X. campestris, and designated as nomenspec ...

microbiology↗

bioRxiv2019

Draft Genome Sequence and intraspecific diversification of the wild crop relative Brassica cretica Lam. using demographic model selection

Crop wild relatives contain great levels of genetic diversity, representing an invaluable resource for crop improvement. Many of their traits have the potential to help crops become more resistant and resilient, and adapt to the new conditions that they will experience due to climate change. An impressive global effort occurs for the conservation of various wild crop relatives and facilitates their use in crop breeding for food security.\n\nThe genus Brassica is listed in Annex I of the International Treaty on Plant Genetic Resources for Food and Agriculture. Brassica oleracea (or wild cabbage) is a species native to coastal southern and western Europe that has become established as an important human food crop plant because of its large reserves stored over the winter in its leaves.\n\nBrassica cretica Lam. is a wild relative crop in the brassica group and B. cretica subsp. nivea has been suggested as a separate subspecies. The species B. cretica has been proposed as a potential gene donor to a number of crops in the brassica group, including broccoli, Brussels sprout, cabbage, cauliflower, kale, swede, turnip and oilseed rape.\n\nHere, we present the draft de novo genome assemblies of four B. cretica individuals, including two B. cretica subsp. nivea and two B. cretica.\n\nDe novo assembly of Illumina MiSeq genomic shotgun sequencing data yielded 243,461 contigs totalling 412.5 Mb in length, corresponding to 122 % of the estimated genome size of B. cretica (339 Mb). According to synteny mapping and phylogenetic analysis of conserved genes, B. cretica genome based on our sequence data reveals approximately 30.360 proteins.\n\nFurthermore, our demographic analysis based on whole genome data, suggests that distinct populations of B. cretica are not isolated. Our findings suggest that the classification of the B. cretica in distinct subspecies is not supported from the genome sequence data we analyzed.

genomics↗