Cours du 27 mai 2015

Intervenant : Ioan Negrutiu, Professeur Emérite, Ecole normale supérieure de Lyon, coordonnateur des cours Bioresources and Biodiversity et Science et Société
http://institutmichelserres.ens-lyon.fr/spip.php?article459

Abstract

Plants are the main producers of biomass and as such they represent the matrix and engine of complex and resilient ecosystems on land. They operate as cellular and biochemical factories that shape life patterns in the biosphere.
The evolution of flowering plants has accelerated these trends. The main evolutionary innovations and optimizations are discussed : robust productivity and species and habitat diversity, rich and multifunctional secondary metabolism, flower structures with closed carpels, double fertlization, fruits. The angiosperm seed bears embryo and endosperm structures. Last but not least, together with mammals, flowering plants are placental organisms.
All these evolutionary undertakings have been explored and exploited through domestication and plant breeding. The results have been and are extraordinary. Seed production for food and feed is a case in point. The endosperm in monocots and the cotyledons in dicots synthesize and process storage molecules : sugars, lipids, and proteins. The origin, structure, diversity, and processing capacities of storage proteins are highlighted.

There is a triple take-home message :

• The evolutionary potential of flowering plants is a combination of modular and sequential developmental capacities (continuous growth), coupled to robustness-plasticity balance (including epigenetic regulations) ;
• Potent agriculture systems and thus sophisticated human societies have only been possible through the essentially unlimited developmental potential (morphological and biochemical) of flowering plants ;
• Storage proteins - the green proteins of the world, are the dominant challenge in the making of sustainable agriculture systems. As such they play a critical role in food systems, food political economy, and geopolitics.