Climate change, loss of (bio)diversity, natural ressource depletion, social marginalization etc: Our adaptation and mitigation contribution

The environmental and social challenges of the planet are a sad reality. Organic Agriculture advocates often espouse its contributions to mitigating the negative effects of farming. But mitigation alone is not enough. Farmers also need to adapt to a changed climate, reduced biodiversity and depleted resources as well as to an ever-changing socio-cultural environment

Carpel development

International audienceThe carpel is the female reproductive organ that encloses the ovules in the flowering plants or angiosperms. The origin of the carpel and its subsequent morphological modifications were probably of vital importance to the evolution of the angiosperms, and the carpel is also very important as the precursor organ to the fruit. Here we describe the general attributes of the angiosperm carpel and several hypotheses for its evolutionary origin. As carpels share many developmental processes with leaves, we describe these processes in the leaf, and then detail the regulation of carpel and fruit development in the model angiosperm Arabidopsis thaliana. We also describe the relationship between carpel formation and the arrest of organ proliferation which occurs at the centre of the Arabidopsis floral meristem. We then provide a brief overview of carpel development in angiosperms occupying important phylogenetic positions, including ANA grade angiosperms, monocots, basal eudicots and core eudicots, focussing on the probable ancestral state of the carpel in each case, and on the available molecular and genetic data. We end with a brief discussion of future research directions relating to carpel and fruit development

Unravelling cell wall formation in the woody dicot stem

Populus is presented as a model system for the study of wood formation (xylogenesis). The formation of wood (secondary xylem) is an ordered developmental process involving cell division, cell expansion, secondary wall deposition, lignification and programmed cell death. Because wood is formed in a variable environment and subject to developmental control, xylem cells are produced that differ in size, shape, cell wall structure, texture and composition. Hormones mediate some of the variability observed and control the process of xylogenesis. High-resolution analysis of auxin distribution across cambial region tissues, combined with the analysis of transgenic plants with modified auxin distribution, suggests that auxin provides positional information for the exit of cells from the meristem and probably also for the duration of cell expansion. Poplar sequencing projects have provided access to genes involved in cell wall formation. Genes involved in the biosynthesis of the carbohydrate skeleton of the cell wall are briefly reviewed. Most progress has been made in characterizing pectin methyl esterases that modify pectins in the cambial region. Specific expression patterns have also been found for expansins, xyloglucan endotransglycosylases and cellulose synthases, pointing to their role in wood cell wall formation and modification. Finally, by studying transgenic plants modified in various steps of the monolignol biosynthetic pathway and by localizing the expression of various enzymes, new insight into the lignin biosynthesis in planta has been gained.Journal ArticleResearch Support, Non-U.S. Gov'tReviewinfo:eu-repo/semantics/publishe