Wheat arabinoxylans: Exploiting variation in amount and composition to develop enhanced varieties

Arabinoxylans (AX) are the major polymers of wheat grain cell walls. The content and the structure of AX polymers show large differences between tissues and between wheat cultivars that affect the end-use properties and nutritional quality of the grain. The development of new wheat cultivars with enhanced quality, therefore, requires methods to exploit this variation and it is essential to understand and modulate the mechanisms controlling the key events of cell-wall polymer synthesis.This paper summarises recent knowledge on the structure and physicochemical properties of AX including variation between cultivars and tissues, methods for analysis and screening, biosynthetic mechanisms and approaches to identifying key genes. This knowledge is essential to understand AX properties and defined possible targets for plant breeding.     

Genotype and environment effects on the contents of vitamins B1, B2, B3, and B6 in wheat grain

The total contents of thiamine (vitamin B1), riboflavin (B2), and pyridoxine (B6) and the bioavailable forms of niacin (B3) were determined on wholemeal flours of 24 winter wheat varieties grown on four sites (United Kingdom, Poland, France, and Hungary) in 2007 and of two spring varieties grown on the same sites with the exception of Poland. The contents of vitamins B1 (5.53-13.55 μg/g dw), B2 (0.77-1.40 μg/g dw), and B6 (1.27-2.97 μg/g dw) were within the ranges reported previously, while the content of bioavailable vitamin B3 (0.16-1.74 μg/g dw) was about 10-15% of the total contents of vitamin B3 reported in previous studies. Strong correlations were observed between the contents of vitamins B1, B3, and B6, and partitioning of the variance in the contents of these three B vitamins showed that between 48 and 70% was accounted for by the environment. By contrast, the content of vitamin B2 was not correlated with the contents of other B vitamins, and 73% of the variance was ascribed to the error term, which suggests that this trait may be influenced by genotype × environment interactions. Whereas the contents of vitamins B1, B3, and B6 were correlated positively with the mean temperature from heading to harvest (r > 0.8), the content of vitamin B2 was positively correlated with precipitation during the 3 months prior to heading. These results are discussed in relation to the development of new wheat varieties with enhanced health benefits.     

Long-term feeding ecology and habitat use in harbour porpoises Phocoena phocoena from Scandinavian waters inferred from trace elements and stable isotopes

Background  

We investigated the feeding ecology and habitat use of 32 harbour porpoises by-caught in 4 localities along the Scandinavian coast from the North Sea to the Barents Sea using time-integrative markers: stable isotopes (δ¹³C, δ¹⁵N) and trace elements (Zn, Cu, Fe, Se, total Hg and Cd), in relation to habitat characteristics (bathymetry) and geographic position (latitude).     

Impact of city historical management on soil organic carbon stocks in Paris (France)

Journal of Soils and Sediments - Assessments of urban soil organic carbon stock (SOCS) are scant because citywide data are scarce. Moreover, we do not know which factors mostly explain SOCS spatial...     

Crop border and mineral oil sprays used in combination as physical control methods of the aphid‐transmitted potato virus Y in potato

BACKGROUND: The objectives of this work were to determine if the control of potato virus Y (PVY, genus Potyvirus, family Potyviridae) in seed potato could be improved by combining border crops and mineral oil sprays, and if the border crop acts as a barrier or a virus sink. RESULTS: Field tests over 3 years confirmed that mineral oils alone are an effective barrier to PVY, and showed that borders alone act as a PVY sink. Combining the familiar mineral oil and the more recent crop border methods was almost twice as effective in reducing PVY incidence as either one used alone. The combination provided consistently high PVY control compared with the variable and often lower level of control by either method alone. The contribution of the oil to PVY reduction was similar whether it was applied to the border, the center seed plot, or both. Oil application to the border alone should not affect efficacy and would help keep control costs down. CONCLUSION: Combining border and oil provided the best reduction in PVY incidence 3 years out of 3, providing producers with a tool to reduce year‐to‐year variation in the effectiveness of crop borders or oil sprays used separately. © Her Majesty the Queen in Right of Canada, as represented by the Minister of Agriculture and Agri‐Food Canada. Published by John Wiley and Sons, Ltd.     

Effects of temperature and wetness duration on conidial infection, latent period and asexual sporulation of Pyrenopeziza brassicae on leaves of oilseed rape

Experiments in controlled environments were carried out to determine the effects of temperature and leaf wetness duration on infection of oilseed rape leaves by conidia of the light leaf spot pathogen, Pyrenopeziza brassicae . Visible spore pustules developed on leaves of cv. Bristol inoculated with P. brassicae conidia at temperatures from 4 to 20°C, but not at 24°C; spore pustules developed when the leaf wetness duration after inoculation was longer than or equal to approximately 6 h at 12–20°C, 10 h at 8°C, 16 h at 6°C or 24 h at 4°C. On leaves of cvs. Capricorn or Cobra, light leaf spot symptoms developed at 8 and 16°C when the leaf wetness duration after inoculation was greater than 3 or 24 h, respectively. The latent period (the time period from inoculation to first spore pustules) of P. brassicae on cv. Bristol was, on average, approximately 10 days at 16°C when leaf wetness duration was 24 h, and increased to approximately 12 days as temperature increased to 20°C and to 26 days as temperature decreased to 4°C. At 8°C, an increase in leaf wetness duration from 10 to 72 h decreased the latent period from approximately 25 to 16 days; at 6°C, an increase in leaf wetness duration from 16 to 72 h decreased the latent period from approximately 23 to 17 days. The numbers of conidia produced were greatest at 12–16°C, and decreased as temperature decreased to 8°C or increased to 20°C. At temperatures from 8 to 20°C, an increase in leaf wetness duration from 6 to 24 h increased the production of conidia. There were linear relationships between the number of conidia produced on a leaf and the proportion of the leaf area covered by 'lesions' (both log₁₀-transformed) at different temperatures.     

Correction to: Coupling landscape graph modeling and biological data: a review

Landscape Ecology - In the original publication of the article, the sixth author name has been misspelt. The correct name is given in this Correction. The original article has been corrected.     

Multi-scale impacts of urbanization on species distribution within the genus Tetramorium

Landscape Ecology - Urbanization is a global change which deeply impacts landscapes. Long studied through transects along urbanization gradients, ecological response to urbanization can now be...     

Using landscape graphs to delineate ecologically functional areas

Context

Landscape graphs are widely used to model connectivity and to support decision-making in conservation planning. Compartmentalization methods applied to such graphs aim to define clusters of highly interconnected patches. Recent studies show that compartmentalization based on modularity is suitable, but it applies to non-weighted graphs whereas most landscape graphs involve weighted nodes and links.

Objectives

We propose to adapt modularity computation to weighted landscape graphs and to validate the relevance of the resulting compartments using demographic or genetic data about the patches.

Methods

A weighted adjacency matrix was designed to express potential fluxes, associating patch capacities and inter-patch distances. Eight weighting scenarios were compared. The statistical evaluation of each compartmentalization was based on Wilks’ Lambda. These methods were performed on a grassland network where patches are documented by annual densities of water voles in the Jura massif (France).

Results

The scenarios in which patch capacity is assigned a small weight led to the more relevant results, giving high modularity values and low Wilks’ Lambda values. When considering a fixed number of compartments, we found a significant negative correlation between these two criteria. Comparison showed that compartments are ecologically more valid than graph components.

Conclusions

The method proposed is suitable for designing ecologically functional areas from weighted landscape graphs. Maximum modularity values can serve as a guide for setting the parameters of the adjacency matrix.

     

Changes in fatty acid and sterol composition during oogenesis in the pearl oyster Pinctada margaritifera

The fatty acid and sterol composition of the oyster Pinctada margaritifera during oogenesis and in eggs was analysed. No major differences were observed during oogenesis, but the egg composition was significantly different from that of gonads. The amount of saturated fatty acids was the highest in eggs and the C16:0 predominant (P<5%); by contrast, the amount of 22:6(n‐3) was significantly lower (P<5%) than in gonads. No major differences were observed for the polar lipid (PL) composition during oogenesis. The main free sterols in gonads and eggs were cholesterol and brassicasterol. Among free sterols, the proportion of cholesterol diminished continuously from the beginning to the end of gonad maturation, and this decrease persisted in eggs after spawning. Cholesterol represented 40% to 55% of the sterol ester encountered in gonad and eggs. This study allowed us to investigate the fatty acid and sterol composition during oogenesis of the pearl oyster P. margaritifera, leading to a clearer understanding of the nutritional requirements of pearl oyster during the reproduction process.