Biology subjects

Murrell, J. C.

Publications and source records attributed to Murrell, J. C..

3 recordsLinked to original sources

bioRxiv2021

Soil, senescence and exudate utilisation: Characterisation of the Paragon var. spring bread wheat root microbiome

Conventional methods of agricultural pest control and crop fertilisation are contributing to a crisis of biodiversity loss, biogeochemical cycle dysregulation, and ecosystem collapse. Thus, we must find ecologically responsible means to control disease and promote crop yields. The root-associated microbiome may contribute to this goal as microbes can aid plants with disease suppression, abiotic stress relief, and nutrient bioavailability. We applied 16S rRNA gene & fungal 18S rRNA gene (ITS2 region) amplicon sequencing to profile the diversity of the bacterial, archaeal & fungal communities associated with the roots of UK elite spring bread wheat variety Triticum aestivum var. Paragon in different soils and developmental stages. This revealed that community composition shifted significantly for all three groups across compartments. This shift was most pronounced for bacteria and fungi, while we observed weaker selection on the ammonia oxidising archaea-dominated archaeal community. Across multiple soil types we found that soil inoculum was a significant driver of endosphere community composition, however several bacterial families were identified as core enriched taxa in all soil conditions. The most abundant of these were Streptomycetaceae and Burkholderiaceae. Moreover, as the plants senesce, both families were reduced in abundance, indicating that input from the living plant was required to maintain their abundance in the endosphere. To understand which microbes are using wheat root exudates in the rhizosphere, root exudates were labelled in a 13CO2 DNA stable isotope probing experiment. This shows that bacterial taxa within the Burkholderiaceae family among other core enriched taxa, such as Pseudomonadaceae, were able to use root exudates but Streptomycetaceae were not. Overall, this work provides a better understanding of the wheat microbiome, including the endosphere community. Understanding crop microbiome formation will contribute to ecologically responsible methods for yield improvement and biocontrol in the future.

microbiology↗

bioRxiv2020

Competition-based screening secures the evolutionary stability of a defensive microbiome

Cuticular microbiomes of Acromyrmex leaf-cutting ants are exceptional because they are freely colonizable, and yet the prevalence of Pseudonocardia, a native vertically transmitted symbiont that controls Escovopsis fungus-garden disease, is never compromised. Game theory suggests that competition-based screening can allow the selective recruitment of antibiotic-producing bacteria from the environment, by fomenting and biasing competition for abundant host resources. Mutual symbiont aggression benefits the host and also maintains native symbiont viability. Here we use RNA-stable isotope probing (RNA-SIP) to confirm predictions that Acromyrmex cuticles can maintain a range of microbial symbionts. We then used dual-RNA-sequencing and bioassays to show that vertically transmitted Pseudonocardia strains produce antibacterials that differentially reduce the growth rates of other microbes, ultimately eliminating non-antibiotic-producing strains that might parasitize the symbiosis while still allowing antibiotic-producing Streptomyces strains to survive. Open cuticular microbiomes can thus maintain a specific co-evolved mutualism by restricting access for other bacterial strains.

evolutionary biology↗

bioRxiv2020

Dissecting the toxicity and mitigating the impact of harmful Prymnesium blooms in the UK waters of the Norfolk Broads

Prymnesium parvum is a toxin-producing microalga that causes harmful algal blooms (HABs) globally, frequently leading to massive fish kills that have adverse ecological and economic implications for natural waterways and aquaculture alike. The dramatic effects observed on fish are likely due to algae-produced polyether toxins, known as the prymnesins, but these compounds had not been detected in environmental samples, which has resulted in ambiguity about the true ichthyotoxic entities. Using qPCR, we found elevated levels of both P. parvum and its lytic virus, PpDNAV-BW1, in a fish-killing bloom on the Norfolk Broads, United Kingdom, in March 2015, a site historically plagued by P. parvum blooms. 16S rRNA gene sequencing confirmed that P. parvum dominated the bloom microbial community and that the microbial species diversity changed after recovery of the ecosystem. We also detected, for the first time, the recently discovered B-type prymnesin toxins in Broads waterway samples and gill tissue isolated from a dead fish taken from the study site. Furthermore, Norfolk Broads P. parvum isolates unambiguously produced B-type toxins in laboratory-grown cultures. In addition, a 2-year longitudinal study of the Broads study site showed P. parvum blooms positively correlated with increased temperature and that PpDNAV plays a significant role in P. parvum bloom demise in this natural setting. Finally, we used a field trial to show that treatment with low doses of hydrogen peroxide represents an effective strategy to mitigate blooms of P. parvum in enclosed water bodies.

microbiology↗