Abstract

Polysaccharidic mucilage is a widespread plant trait with diverse features, often present around plant structures in contact with the environment, providing numerous functions including protection and adhesion. Seed mucilage is released upon imbibition and therefore can play roles in the early seedling stages, but the evolutionary origins of this trait are unclear. Its presence in several flowering plant species suggests that it was present in their last common ancestor whereas the extreme inter-species morphological and chemical natural diversity suggests multiple origins. Here, we summarize the recent advances on molecular mechanisms and ecological functions underlying this inter- and intra-species natural diversity. A master regulatory complex balancing carbon partitioning in seed appears to be conserved among flowering plants with a sequential evolution of its molecular components. At the intra-species level, a high polymorphism was detected for a few genes in relation to the observed morphological diversity. Historically, the ecological functions of seed mucilage were mostly related to germination and seed dissemination but recently some exosystemic functions were uncovered such as soil micro-organism control and plant establishment support. These recent advances enable drawing a clearer picture of the seed mucilage evolution, the underlying molecular mechanisms, and the associated ecological roles.