40 research outputs found

    Specific and sensitive detection tools for Xanthomonas arboricola pv. corylina, the causal agent of bacterial blight of hazelnut, developed with comparative genomics

    Get PDF
    Xanthomonas arboricola pv. corylina (Xac; formerly Xanthomonas campestris pv. corylina) is the causal agent of the bacterial blight of hazelnuts, a devastating disease of trees in plant nurseries and young orchards. Currently, there are no PCR assays to distinguish Xac from all other pathovars of X. arboricola. A comparative genomics approach with publicly available genomes of Xac was used to identify unique sequences, conserved across the genomes of the pathogen. We identified a 2,440 bp genomic region that was unique to Xac and designed identification and detection systems for conventional PCR, qPCR (SYBR® Green and TaqMan™), and loop-mediated isothermal amplification (LAMP). All PCR assays performed on genomic DNA isolated from eight X. arboricola pathovars and closely related bacterial species confirmed the specificity of designed primers. These new multi-platform molecular diagnostic tools may be used by plant clinics and researchers to detect and identify Xac in pure cultures and hazelnut tissues rapidly and accurately

    Volcanic impacts on peatland microbial communities: A tephropalaeoecological hypothesis-test

    Get PDF
    Volcanic eruptions affect peatlands around the world, depositing volcanic ash (tephra) and a variety of chemicals including compounds of sulphur. These volcanic impacts may be important for many reasons, in particular sulphur deposition has been shown to suppress peatland methane flux, potentially reinforcing climatic cooling. Experiments have shown that sulphur deposition also forces changes in testate amoeba communities, potentially relating to the reduced methane flux. Large volcanic eruptions in regions with extensive peatlands are relatively rare so it is difficult to assess the extent to which volcanic eruptions affect peatland microbial communities; palaeoecological analyses across tephra layers provide a means to resolve this uncertainty. In this study, testate amoebae were analysed across multiple monoliths from a peatland in southern Alaska containing two tephras, probably representing the 1883 eruption of Augustine Volcano and a 20th Century eruption of Redoubt Volcano. Results showed relatively distinct and often statistically significant changes in testate amoeba community coincident with tephra layers which largely matched the response found in experimental studies of sulphur deposition. The results suggest volcanic impacts on peatland microbial communities which might relate to changes in methane flux

    Managing fruit rot diseases of Vaccinium corymbosum

    Get PDF
    Blueberry is an important perennial fruit crop with expanding consumption and production worldwide. Consumer demand for blueberries has grown due to the desirable flavor and numerous health benefits, and fresh market production in the U.S. has risen in turn. U.S. imports have also increased to satisfy year-round consumer demand for fresh blueberries. Pre- and post-harvest fruit diseases such as anthracnose (caused by Colletotrichum spp.) and botrytis fruit rot (caused by Botrytis spp.) have a significant impact on fruit quality and consumer acceptance. These are also among the most difficult diseases to control in the blueberry cropping system. These latent pathogens can cause significant losses both in the field, and especially during transport and marketplace storage. Although both diseases result in rotted fruit, the biology and infection strategies of the causal pathogens are very different, and the management strategies differ. Innovations for management, such as improved molecular detection assays for fungicide resistance, postharvest imaging, breeding resistant cultivars, and biopesticides have been developed for improved fruit quality. Development and integration of new strategies is critical for the long-term success of the blueberry industry

    Metabolic Versatility and Antibacterial Metabolite Biosynthesis Are Distinguishing Genomic Features of the Fire Blight Antagonist Pantoea vagans C9-1

    Get PDF
    Smits THM, Rezzonico F, Kamber T, et al. Metabolic Versatility and Antibacterial Metabolite Biosynthesis Are Distinguishing Genomic Features of the Fire Blight Antagonist Pantoea vagans C9-1. PLoS ONE. 2011;6(7): e22247.Background: Pantoea vagans is a commercialized biological control agent used against the pome fruit bacterial disease fire blight, caused by Erwinia amylovora. Compared to other biocontrol agents, relatively little is currently known regarding Pantoea genetics. Better understanding of antagonist mechanisms of action and ecological fitness is critical to improving efficacy. Principal Findings: Genome analysis indicated two major factors contribute to biocontrol activity: competition for limiting substrates and antibacterial metabolite production. Pathways for utilization of a broad diversity of sugars and acquisition of iron were identified. Metabolism of sorbitol by P. vagans C9-1 may be a major metabolic feature in biocontrol of fire blight. Biosynthetic genes for the antibacterial peptide pantocin A were found on a chromosomal 28-kb genomic island, and for dapdiamide E on the plasmid pPag2. There was no evidence of potential virulence factors that could enable an animal or phytopathogenic lifestyle and no indication of any genetic-based biosafety risk in the antagonist. Conclusions: Identifying key determinants contributing to disease suppression allows the development of procedures to follow their expression in planta and the genome sequence contributes to rationale risk assessment regarding the use of the biocontrol strain in agricultural systems

    Plant Agricultural Streptomycin Formulations Do Not Carry Antibiotic Resistance Genesâ–¿

    No full text
    Streptomycin is used in plant agriculture for bacterial disease control, particularly against fire blight in pome fruit orchards. Concerns that this may increase environmental antibiotic resistance have led to bans or restrictions on use. Experience with antibiotic use in animal feeds raises the possible influence of formulation-delivered resistance genes. We demonstrate that agricultural streptomycin formulations do not carry producer organism resistance genes. By using an optimized extraction procedure, Streptomyces 16S rRNA genes and the streptomycin resistance gene strA were not detected in agricultural streptomycin formulations. This diminishes the likelihood for one potential factor in resistance development due to streptomycin use
    corecore