Temporal and spatial dynamics in the apple flower microbiome in the presence of the phytopathogen Erwinia amylovora

Plant microbiomes have important roles in plant health and productivity. However, despite flowers being directly linked to reproductive outcomes, little is known about the microbiomes of flowers and their potential interaction with pathogen infection. Here, we investigated the temporal spatial dynamics of the apple stigma microbiome when challenged with a phytopathogen Erwinia amylovora, the causal agent of fire blight disease. We profiled the microbiome from the stigmas of individual flowers, greatly increasing the resolution at which we can characterize shifts in the composition of the microbiome. Individual flowers harbored unique microbiomes at the operational taxonomic unit level. However, taxonomic analysis of community succession showed a population gradually dominated by bacteria within the families Enterobacteriaceae and Pseudomonadaceae. Flowers inoculated with E. amylovora established large populations of the phytopathogen, with pathogen-specific gene counts of >3.0 × 10⁷ in 90% of the flowers. Yet, only 42% of inoculated flowers later developed fire blight symptoms. This reveals that pathogen abundance on the stigma is not sufficient to predict disease outcome. Our data demonstrate that apple flowers represent an excellent model in which to characterize how plant microbiomes establish, develop, and correlate with biological processes such as disease progression in an experimentally tractable plant organ.Subject terms: Microbial ecology, Non-coding RNAs     

Sub-zero temperatures and large-scale weather patterns induce tooth damage in Icelandic arctic foxes

Tooth damage in carnivores can reflect shifts in both diet and feeding habits, and in large carnivores, it is associated with increased bone consumption. Variation in tooth condition in Icelandic arctic foxes, a mesocarnivore, was recorded from 854 individual foxes spanning 29 years. We hypothesized that annual climatic variations, which can influence food abundance and accessibility, will influence tooth condition by causing dietary shifts toward less edible prey. We examined tooth condition in relation to four climatic predictors: mean annual winter temperature, indices of both the El Niño anomaly and North Atlantic subpolar gyre (SPG), and the number of rain-on-snow days (ROS). We found unequivocal evidence for a strong effect of annual climate on tooth condition. Teeth of Icelandic foxes were in better condition when winter temperatures were higher, when the SPG was more positive, and when the number of ROS was low. We also found a substantial subregional effect with foxes from northeastern Iceland having lower tooth damage than those from two western sites. Contradicting our original hypothesis that foxes from northeastern Iceland, where foxes are known to scavenge on large mammal remains (e.g., sheep and horses), would show the highest tooth damage, we suggest that western coastal sites exhibited greater tooth damage because cold winter temperatures lowered the availability of seabirds, causing a shift in diet toward abrasive marine subsidies (e.g., bivalves) and frozen beach wrack. Our study shows that monitoring tooth breakage and wear can be a useful tool for evaluating the impact of climate on carnivore populations and that climate change may influence the condition and fitness of carnivores in complex and potentially conflicting ways.     

Nutritional composition of water hyacinths grown on domestic sewage

A nutrient analysis of water hyacinths grown in sewage wastewaters was conducted. Crude protein averaged 32.9% dry weight in the leaves, where it was most concentrated. The amino acid content of water hyacinth leaves was found to compare favorably with that of soybean and cottonseed meal. The vitamin and mineral content of dried water hyacinths met or exceeded the FAO recommended daily allowance, in many cases. It is concluded that in favorable climatic zones, water hyacinths grown in enriched mediums, such as sewage lagoons, could potentially serve as a substantial dietary supplement or nutrient source.     

The use of fumigants and anticoagulant rodenticides on game estates in Great Britain

Several studies have highlighted the potential risk to nontarget wildlife associated with accidental exposure to vertebrate control agents. In order to provide information that may assist in the mitigation of this problem, we questioned 215 gamekeepers in Great Britain about the use of vertebrate control agents on the land for which they were responsible. Fumigants were used to control Rabbits Oryctolagus cuniculus by 59% of gamekeepers. Use of fumigants was more common than on farms in general. 91% of gamekeepers reported the use of rodenticides, 95% of which were anticoagulants. Patterns of rodenticide use were similar to those on arable farms, though chlorophacinone and warfarin were used more commonly on game estates. Future studies of the exposure of nontarget wildlife to anticoagulants should be expanded to include these compounds. Rodenticides were apparently used in accordance with label recommendations in most cases. However, better information and guidelines for users may improve standards of agent application and reduce potential risks to nontarget wildlife.