Does manipulation of fruit-tree architecture affect the development of pests and pathogens? A case study in an organic apple orchard

Summary

Centrifugal training, based on the extinction procedure, is an innovative type of apple tree training recently used in French apple orchards. A thinning cut of fruiting spurs along the trunk and on the proximal and underside parts of the fruiting branches modifies the within-tree leaf density and light environment, which is likely to affect the development of some apple pests and pathogens. In this study, development of the most serious foliar pests (aphids, mites) and disease (apple scab) was assessed over 3 years in an organic apple orchard with two training systems: the centrifugal training (CT) system, and the Original Solaxe (OS) system, using a bent axis with no removal of fruiting spurs, as a control. Infestation levels were significantly lower in 2002 and 2004 in the CT system than in the OS system for the most prevalent pest, the rosy apple aphid, Dysaphis plantaginea and, in 2003, for the red spider mite, Panonychus ulmi. Infestation by the green apple aphid, Aphis pomi, was higher in June 2002 and 2004 and lower in June 2003 in the CT system, compared to the OS control. The incidence of apple leaf scab was lower in the CT system than in the OS control in Spring 2002 and Spring 2004; but, later in the Summer, it increased more in CT trees, resulting in no difference between training systems in the levels of fruit infection at harvest. Hypotheses considered were based mainly on: (i) the removal of pests or inoculum due to the thinning cut of fruiting spurs for CT trees; (ii) effects on within-tree microclimate, providing a more aerated canopy in the CT system; (iii) shoot density and distribution, allowing greater distances between growing shoots in CT trees; and/or (iv) the shoot growth dynamics, allowing the presence of attractive or susceptible leaves in late June. Since the most serious apple pests and diseases were less prevalent in the CT system over the 3 years of the experiment, CT may prove to be a complementary, sustainable means to contribute to crop protection, especially in organic or integrated pest management orchards.     

Influence of the allelic variants encoded at the Gli-B1 locus, responsible for a major allergen of wheat, on IgE reactivity for patients suffering from food allergy to wheat

Wheat presents an important genetic diversity that could be useful to look for cultivars with reduced allergencity. omega5-Gliadins have been described as major allergens for wheat allergic patients suffering from wheat-dependent exercise-induced anaphylaxis (WDEIA) and some cases of chronic urticaria (U). Our objective was to study the influence of genetic variability at the Gli-B1 locus encoding for omega5-gliadins on the reactivity of IgE antibodies from these patients. We selected cultivars expressing 13 alleles at Gli-B1 including a wheat/rye translocation and studied the reactivity to gliadins of a rabbit antiserum specific for omega5-gliadins and of IgE from 10 patients. The antiserum and IgE from nine patients with WDEIA and U strongly detected omega5-gliadins expressed by most of the Gli-B1 alleles but showed no or faint responses to the gliadins and secalins extracted from the translocated wheat. The selection of genotypes lacking the Gli-B1 locus may reduce wheat allergenicity.     

ALS-based estimation of plot volume and site index in a eucalyptus plantation with a nonlinear mixed-effect model that accounts for the clone effect

Introduction  

Most airborne laser scanning (ALS) studies have been carried out in semi-natural forests, but some research has also been carried out in plantations. Results indicate that methods similar to those which are used in semi-natural forest are also usable in plantation forestry. The study was conducted in a pulpwood plantation growing Eucalyptus urograndis in Bahia State, Brazil.     

Elimination of common scab sensitive progeny from a potato breeding population using thaxtomin A as a selective agent

Common scab is one of the most important soil‐borne diseases of potato and is difficult to control. Selection of potato breeding lines for resistance to common scab is also cumbersome due to environmental factors influencing symptom development and an erratic spatial distribution of the scab pathogens (Streptomyces spp.) in the field. The bacterial phytotoxin thaxtomin A, which causes scab symptoms, can be used to screen large numbers of potato seedlings for tolerance in vitro, but few studies have investigated whether the results correspond to resistance to common scab observed in the field. In this study, 120 F1 potato progeny from a single cross were screened in vitro by exposing the seedlings to thaxtomin A added to the culture medium. Eighteen genotypes were selected based on high sensitivity or tolerance using shoot growth as the criterion, multiplied in vitro, and tested for resistance to common scab caused by S. turgidiscabies and S. scabies in a glasshouse and in three different fields. Evaluation of ca. 6500 tubers showed that the 18 potato genotypes differed in scab indices and disease severity (P < 0·0001). The relative shoot height in vitro (thaxtomin A used at 0·5 μg mL^?1) and the scab index in the field showed significant correlation (r_s = ?0·463, P = 0·0528, n = 18), also consistent with the results obtained under controlled conditions in the glasshouse. Hence, the in vitro bioassay may be used to discard scab‐susceptible genotypes and elevate the overall levels of common scab resistance in the potato breeding populations.     

Characterization of a common susceptibility locus for asthma-related traits

Susceptibility to asthma depends on variation at an unknown number of genetic loci. To identify susceptibility genes on chromosome 7p, we adopted a hierarchical genotyping design, leading to the identification of a 133-kilobase risk-conferring segment containing two genes. One of these coded for an orphan G protein-coupled receptor named GPRA (G protein-coupled receptor for asthma susceptibility), which showed distinct distribution of protein isoforms between bronchial biopsies from healthy and asthmatic individuals. In three cohorts from Finland and Canada, single nucleotide polymorphism-tagged haplotypes associated with high serum immunoglobulin E or asthma. The murine ortholog of GPRA was up-regulated in a mouse model of ovalbumin-induced inflammation. Together, these data implicate GPRA in the pathogenesis of atopy and asthma.     

Inventory of aspen trees in spruce dominated stands in conserva-tion area

Background: The occurrence of aspen trees increases the conservation value of mature conifer dominated forests.Aspens typically occur as scattered individuals among major tree species, and therefore the inventory of aspens is challenging.Methods: We characterized aspen populations in a boreal nature reserve using diameter distribution, spatial pattern, and forest attributes: volume, number of aspens, number of large aspen stems and basal area median diameter. The data were collected from three separate forest stands in Koli National Park, eastern Finland. At each site, we measured breast height diameter and coordinates of each aspen. The comparison of inventory methods of aspens within the three stands was based on simulations with mapped field data. We mimicked stand level inventory by locating varying numbers of fixed area circular plots both systematically and randomly within the stands. Additionally, we also tested if the use of airborne laser scanning(ALS) data as auxiliary information would improve the accuracy of the stand level inventory by applying the probability proportional to size sampling to assist the selection of field plot locations.Results: The results showed that aspens were always clustered, and the diameter distributions indicated different stand structures in the three investigated forest stands. The reliability of the volume and number of large aspen trees varied from relative root mean square error figures above 50% with fewer sample plots(5–10) to values of25%–50% with 10 or more sample plots. Stand level inventory estimates were also able to detect spatial pattern and the shape of the diameter distribution. In addition, ALS-based auxiliary information could be useful in guiding the inventories, but caution should be used when applying the ALS-supported inventory technique.Conclusions: This study characterized European aspen populations for the purposes of monitoring and management of boreal conservation areas. Our results suggest that if the number of sample plots is adequate,i.e. 10 or more stand level inventory will provide accurate enough forest attributes estimates in conservation areas(minimum accuracy requirement of RMSE% is 20%–50%). Even for the more ecologically valuable attributes, such as diameter distribution, spatial pattern and large aspens, the estimates are acceptable for conservation purposes.     

Enrichment of conjugated linoleic acid in oats (Avena sativa L.) by microbial isomerization

A method for microbial isomerization of oat linoleic acid to conjugated linoleic acid (CLA) was developed. The method includes hydrolysis of oat lipids in aqueous flour slurries by the endogenous oat lipase. Then, the flour slurry containing free linoleic acid is utilized as a substrate for the isomerization reaction carried out by resting cells of Propionibacterium freudenreichii ssp. shermanii. The isomerization reaction progressed most effectively when, after the lipid hydrolysis period, the pH of the slightly acidic oat slurry was elevated to 8.0-8.5 and maintained at this range. With slurries containing 5% (w/v) oat flour, the amounts of CLA formed per dry matter were up to 10.1 mg/g corresponding to 102 mg/g lipids or 0.44 mg/mL slurry. Increments in the flour content up to 15% increased the volumetric production of CLA to 0.85 mg/mL. The proportion of the cis-9,trans-11 isomer was 80% of the total CLA formed. CLA could be concentrated into the solid material of the oat slurry by acidification.     

Climate change mitigation through increased wood use in the European construction sector—towards an integrated modelling framework

Using wood as a building material affects the carbon balance through several mechanisms. This paper describes a modelling approach that integrates a wood product substitution model, a global partial equilibrium model, a regional forest model and a stand-level model. Three different scenarios were compared with a business-as-usual scenario over a 23-year period (2008?C2030). Two scenarios assumed an additional one million apartment flats per year will be built of wood instead of non-wood materials by 2030. These scenarios had little effect on markets and forest management and reduced annual carbon emissions by 0.2?C0.5% of the total 1990 European GHG emissions. However, the scenarios are associated with high specific CO₂ emission reductions per unit of wood used. The third scenario, an extreme assumption that all European countries will consume 1-m³ sawn wood per capita by 2030, had large effects on carbon emission, volumes and trade flows. The price changes of this scenario, however, also affected forest management in ways that greatly deviated from the partial equilibrium model projections. Our results suggest that increased wood construction will have a minor impact on forest management and forest carbon stocks. To analyse larger perturbations on the demand side, a market equilibrium model seems crucial. However, for that analytical system to work properly, the market and forest regional models must be better synchronized than here, in particular regarding assumptions on timber supply behaviour. Also, bioenergy as a commodity in market and forest models needs to be considered to study new market developments; those modules are currently missing.     

Parr dispersal between streams via a marine environment: A novel mechanism behind straying for anadromous brown trout?

Otolith Sr:Ca profiles demonstrated that juvenile anadromous brown trout (ABT) Salmo trutta may descend to the brackish waters of the Baltic Sea from their natal streams as parr or fry and then migrate into non‐natal streams before transforming into smolt. To our knowledge, no such published documentation exists for ABT. The ecological significance of this life‐history strategy is presently not clear. However, stream shifting through the marine environment should to be considered with regard to stock management and the assessment and restoration of salmonid populations and their potential habitats.