Dominique Desclaux

Developments in breeding cereals for organic agriculture

The need for increased sustainability of performance in cereal varieties, particularly in organic agriculture (OA), is limited by the lack of varieties adapted to organic conditions. Here, the needs for breeding are reviewed in the context of three major marketing types, global, regional, local, in European OA. Currently, the effort is determined, partly, by the outcomes from trials that compare varieties under OA and CA (conventional agriculture) conditions. The differences are sufficiently large and important to warrant an increase in appropriate breeding. The wide range of environments within OA and between years, underlines the need to try to select for specific adaptation in target environments. The difficulty of doing so can be helped by decentralised breeding with farmer participation and the use of crops buffered by variety mixtures or populations. Varieties for OA need efficient nutrient uptake and use and weed competition. These and other characters need to be considered in relation to the OA cropping system over the whole rotation. Positive interactions are needed, such as early crop vigour for nutrient uptake, weed competition and disease resistance. Incorporation of all characteristics into the crop can be helped by diversification within the crop, allowing complementation and compensation among plants. Although the problems of breeding cereals for organic farming systems are large, there is encouraging progress. This lies in applications of ecology to organic crop production, innovations in plant sciences, and the realisation that such progress is central to both OA and CA, because of climate change and the increasing costs of fossil fuels.

Membrane proteomics: use of additive main effects with multiplicative interaction model to classify plasma membrane proteins according to their solubility and electrophoretic properties.

Recent efforts at the proteomic level were employed to describe the protein equipment of the plasma membrane of the model plant Arabidopsis thaliana. These studies had revealed that the plasma membrane is rich in extrinsic proteins but came up against two major problems: (i) few hydrophobic proteins were recovered in two‐dimensional electrophoresis gels, and (ii) many plasma membrane proteins had no known function or were unknown in the database despite extensive sequencing of the Arabidopsis genome. In this paper, several methods expected to enrich a membrane sample in hydrophobic proteins were compared. The optimization of solubilization procedures revealed that the detergent to be used depends on the lipid content of the sample. The corresponding proteomes were compared with the statistical model AMMI (additive main effects with multiplicative interaction) that aimed at regrouping proteins according to their solubility and electrophoretic properties. Distinct groups emerged from this analysis and the identification of proteins in each group allowed us to assign specific features to several of them. For instance, two of these groups regrouped very hydrophobic proteins, one group contained V‐ATPase subunits, another group contained proteins with one transmembrane domain as well as proteins known to interact with membrane proteins. This study provides methodological tools to study particular classes of plasma membrane proteins and should be applicable to other cellular membranes.

Impact of drought stress on the phenology of two soybean ( Glycine max L. Merr) cultivars

Abstract Drought stresses modify the phenology of plants, and thus affect the yield components. The impact of various periods of water stress on the organ appearance rate and on the durations of the main vegetative and reproductive periods was studied under greenhouse conditions on soybean cultivars differing by type of growth. The two cultivars, Weber and Spot, maturity group I, indeterminate and determinate respectively, were subjected to drought stress (30% PAW) during a main developmental stage: i.e., vegetative, flowering, pod lengthening or seed filling. Drought stress seemed to trigger a signal that caused an early switch of plant development from vegetative to reproductive. Appearance of nodes initiated during stress was delayed, resulting in a small number of nodes produced, whereas flower and pod appearance were hastened. Each reproductive phase was shorter under stress, mainly because of the appearance of new organs that prevented the emergence of organs belonging to the earlier ontogenetic phases. The seed-filling stage and the final stage in seed abortion began earlier in stressed plants and the duration of the maturation period was significantly reduced by stress during seed filling, leading to accelerated senescence. The cultivars differed mostly with respect to their strategies of partitioning between the main stem and branches. Under stress, the duration of the main reproductive phase was increased on the main stem but reduced on the branches in cultivar Weber, whereas the opposite response was noted in cultivar Spot.

Does the Seed Sector Offer Meet the Needs of Organic Cropping Diversity? Challenges for Organic Crop Varieties

This chapter aims to study the current balance between the offer and demand of the organic seed sector and how the breeding system can be adapted to the diversity of needs.