Chromosomal and Plasmid Diversity of Agrobacterium Strains Isolated from Ficus benjamina Tumors

Agrobacteria were previously isolated from tumors developing on branches and aerial and hypogeous roots of weeping fig plants in Italy and in The Netherlands. A representative group of 48 strains was analyzed by PCR–RFLP of 16S and 16S + IGS ribosomal regions, PCR–RFLP of six Ti plasmid (pTi) regions and characterized for plasmid content. Two groups of agrobacteria were separated by cluster analysis of PCR–RFLP profiles of rrs gene: seventeen strains were similar to the new species Agrobacterium larrymoorei, while the remaining strains were included within the agrobacterium biovar 1 group. Sixteen different plasmid profiles from one to five plasmids were observed. In addition, 21 ribotypes and 20 pTi structures were arranged in many different combinations, showing that fig agrobacteria were characterized by a wide heterogeneity. A general lack of correlation between strain ribotypes and plasmid content was observed.     

Localization of alkylresorcinols in wheat,rye and barley kernels

Cereal alkylresorcinols (AR), a group of phenolic lipids mainly found in the outer parts of wheat and rye kernels, are currently being studied for the possibility to use them as biomarkers for the intake of whole grain wheat and rye foods. In this work, AR were localised in grains by using light microscopy and gas chromatographic analysis of hand-dissected botanical and pearling fractions. GC-analysis of hand-dissected fractions showed that more than 99% of the total AR content was located in an intermediate layer of the caryopsis, including the hyaline layer, testa and inner pericarp. Microscopic examination showed that the outer cuticle of testa/inner cuticle of pericarp was the exact location, and that no AR were found in the endosperm or in the germ, suggesting that AR could be used as a selective marker of testa.     

Biscrolling nanotube sheets and functional guests into yarns

Multifunctional applications of textiles have been limited by the inability to spin important materials into yarns. Generically applicable methods are demonstrated for producing weavable yarns comprising up to 95 weight percent of otherwise unspinnable particulate or nanofiber powders that remain highly functional. Scrolled 50-nanometer-thick carbon nanotube sheets confine these powders in the galleries of irregular scroll sacks whose observed complex structures are related to twist-dependent extension of Archimedean spirals, Fermat spirals, or spiral pairs into scrolls. The strength and electronic connectivity of a small weight fraction of scrolled carbon nanotube sheet enables yarn weaving, sewing, knotting, braiding, and charge collection. This technology is used to make yarns of superconductors, lithium-ion battery materials, graphene ribbons, catalytic nanofibers for fuel cells, and titanium dioxide for photocatalysis.     

Turning back the tide of American mink invasion at an unprecedented scale through community participation and adaptive management

Successful eradications of harmful invasive species have been mostly confined to islands while control programs in mainland areas remain small, uncoordinated and vulnerable to recolonisation. To allow the recovery of threatened native species, innovative management strategies are required to remove invasives from large areas. We took an adaptive approach to achieve large scale eradication of invasive American mink in North East Scotland. The project was centred on the Cairngorms National Park (Scotland), with the primary aim of protecting endangered water vole populations. The project was initiated by scientists and supported and implemented through a partnership comprising a government agency, national park authority and local fisheries boards. Capitalising on the convergent interests of a diverse range of local stakeholders, we created a coordinated coalition of trained volunteers to detect and trap mink. Starting in montane headwaters, we systematically moved down river catchments, deploying mink rafts, an effective detection and trapping platform. Volunteers took increasing responsibility for raft monitoring and mink trapping as the project progressed. Within 3 years, the project removed 376 mink from 10570 km² with the involvement of 186 volunteers. Capture rate within sub-catchments increased with greater connectivity to mink in other sub-catchments and with proximity to the coast where there is more productive habitat. The main factor underpinning the success of this project was functional volunteer participation. The project is a reason for optimism that the tide of invasion can be rolled back on a large scale where the convergent interest of local communities can be harnessed.     

Field effect of P fertilization on N2 fixation rate of Ulex europaeus

European gorse (Ulex europaeus L.) N₂ fixation rate (%Ndfa) was studied in a maritime pine (Pinus pinaster Aït.) oligotrophic forest. Fertilization field trials were carried out on 5 sites with various inputs of phosphorus (0–240 kg P₂O₅·ha^?1). Seven to ten years after pine planting, gorse were sampled to evaluate the effect of P fertilization on gorse %Ndfa, determined using the ¹⁵N natural abundance method. One of the prerequisites of this method is the existence of a significant difference between the ¹⁵N/¹⁴N ratios in the atmospheric N reference and in the stand soil N references. This prerequisite was satisfied for 80 of 120 cases. The average %Ndfa was high (70 ± 3%) but with high local variability. No significant difference in %Ndfa was detected among P treatments. Nitrogen concentration of gorse was significantly higher in the highest dose treatments compared to the control.     

Weeds,aphids, and specialist parasitoids and predators benefit differently from organic and conventional cropping of winter cereals

The aphid–natural enemy interaction in winter wheat fields constitutes a complex system that has been frequently studied because of its implication for biological control. However, not all of the aphids living in cereal fields are crop pests, as there are also aphids living on weeds that may serve as alternative hosts or prey for aphid parasitoids or predators. In this context, a concomitant survey of the plant and insect communities was conducted to understand how different plant communities affect the abundance and richness of aphids and the interactions with their natural enemies. The plant community was split into functional groups (grasses, legumes and forbs), and the aphid community was divided into feeding groups according to their host preferences (specialists in grasses or forbs). The grass aphids, which dominated the total aphid catches, responded positively to grass cover, which was particularly enhanced in the conventional fields. Conversely, the forb aphids, which mainly conditioned the total species richness of the aphids, were closely correlated with the local abundance of legumes. The system of cereal aphid-parasitoids was enhanced in the conventional fields, where the abundance of grasses was higher, whereas the legumes of the organic fields indirectly played a key role in enhancing the richness of the parasitoids and the abundance of predators. Our findings indicate that a bottom-up effect exists throughout the plant community, aphids, and aphidophagous insects and that plant community characteristics should be considered to better understand cereal aphid control.     

Mutualism between euryhaline tilapia Sarotherodon melanotheron heudelotii and Chlorella sp.—Implications for nano-algal production in warmwater phytoplankton-based recirculating systems

The West-African euryhaline tilapia, Sarotherodon melanotheron heudelotii shift from visually feeding on zooplankton when juveniles to mostly filter feeding on phytoplankton when adults. When reared using an appropriate ration in intensive aquaculture systems, S. m. heudelotii also consume algal-based detritus, and contribute to sediment mineralization, clean up their environment, and ultimately stimulate and sustain algal growth. We analysed such practical advantages for phytoplankton-based recirculating systems, using S. m. heudelotii and Chlorella sp. as biological material originating from the prototype of such a system operated in Senegal. We performed a 24-h factorial design experiment in 36 tubs, cross-classifying three levels of S. m. heudelotii (fishless control, unfed fish, and fed fish) with four levels of Chlorella initial density.Chlorella overall mean density increased significantly from fishless, to unfed fish, and fed fish treatments, and with Chlorella initial density. S. m. heudelotii did not alter nitrogen nor phosphorus concentrations, only affected by algal initial densities. Most ammonia excreted by fish was probably uptaken by Chlorella. Bacteria-mediated diurnal nitrification was possibly an alternative ammonium loss mechanism at highest oxygen concentrations. Algae were not limited by nitrogen or phosphorus but most likely by low dissolved organic carbon availability. Chlorella differential responses with fed vs. unfed Sarotherodon suggest that CO₂ supplied by heterotrophic S. m. heudelotii respiration played a key role. Observed Chlorella growth rates were similar to the highest rates obtained in algal mass cultures, enriched with CO₂, nitrate and phosphate, under artificial lighting.Our results suggest the existence of a Sarotherodon-Chlorella mutualism in our systems, where S. m. heudelotii provide CO₂, the major limiting factor of Chlorella growth, whereas Chlorella oxygenate and detoxify the water media from ammonia, promoting S. m. heudelotii production. This mutualism could be used to optimize photosynthetic suspended-growth aquaculture systems, particularly in the Tropics where light is abundant and temperature is continuously high.     

Using unsupervised learning techniques to assess interactions among complex traits in soybeans

Soybean yield components and agronomic traits are connected through physiological pathways that impose tradeoffs through genetic and environmental constraints. Our primary aim is to assess the interdependence of soybean traits by using unsupervised machine learning techniques to divide phenotypic associations into environmental and genetic associations. This study was performed on large scale, jointly analyzing 14 quantitative traits in a large multi-parental population designed for genetic studies. We collected phenotypes from 2012 to 2015 from a soybean nested association panel with 40 families of approximately 140 individuals each. Pearson and Spearman correlations measured phenotypic associations. A multivariate mixed linear model provided genotypic and environmental correlations. To evaluate relationships among traits, the study used principal component and undirected graphical models from phenotypic, genotypic, and environmental correlation matrices. Results indicate that high phenotypic correlation occurs when traits display both genetic and environmental correlations. In genetic terms, length of reproductive period, node number, and canopy coverage play important roles in determining yield potential. Optimal grain yield production occurs when the growing environment favors faster canopy closure and extended reproductive length. Environmental associations found among yield components give insight into the nature of yield component compensation. The use of unsupervised learning methods provides a good framework for investigating interactions among various quantitative traits and defining target traits for breeding.     

Assessment of molecular detection of Fusarium circinatum in insects and passive spore traps in Pinus radiata plantations

Fusarium circinatum is the causal agent of pitch canker, a destructive disease that threatens natural and planted pine forests around the world. Although pitch canker has caused problems in Spain and Portugal, concerning Europe as a whole, the fungus is not established across the pine distribution area. Its dispersion by wind and/or insect vectors could nevertheless play a role in the colonization of currently uninfected stands. It is therefore crucial to develop monitoring tools for its detection. To this end, we assessed the molecular detection of the pathogen in environmental samples of bark beetles and passive spore traps, collected in two infected Pinus radiata plantations in Basque country, Spain. The spread pattern of F. circinatum was assessed by an experimental design that included insect and spore traps installed at the centre, at the edge and outside the plots. Our results showed that F. circinatum was detected in both types of samples, at almost all collection dates. In both type of samples, positive detections were mainly found at the centre of the plots, a lower proportion at the edge, and very few outside. This suggests that long‐distance dispersion of Fusarium circinatum does not rely on wind spore dispersal neither on insect flight. Our study also shows that molecular methods are a powerful tool to monitor the pathogen in environmental samples.     

Quantitative impact assessment of spray coverage and pest behavior on contact pesticide performance

BACKGROUND: Standard procedures for evaluation of pesticide performance do not take into account pest behavioral response or incomplete spray coverage. In this study, a series of laboratory experiments was conducted with two non‐systemic miticides (propargite and hexythiazox) applied to cotyledon cotton plants, which were subsequently infested with spider mites. The results of these laboratory experiments are discussed through a comprehensive pest population dynamics model. RESULTS: When cotton leaves were submerged in miticide solutions, both miticides provided effective control of spider mites. In a two‐choice test it was demonstrated that propargite was repellent to spider mites, but not hexythiazox. Finally, the spray coverage on cotton plants was varied, and, for both miticides, significantly positive relationships between spray coverage and spider mite mortality were shown. However, propargite required higher spray coverage (20%) than hexythiazox (10%) to control spider mites. A theoretical model showed that, without repellency, the pesticide performance is positively correlated with target pest mobility. If the pesticide is repellent, the probability of exposure decreases, especially for a less mobile pest. CONCLUSION: With an experimental and theoretical modeling approach, it was demonstrated how the combination of behavioral avoidance and low spray coverage can markedly reduce pesticide performance. Copyright © 2012 Society of Chemical Industry