Abstract EN:

The nutritional quality of legume seeds is an important economic issue in the light of the growing demand for vegetable protein for livestock consumption and humans. Certain transcription factors (TFs) play an important role in the transcriptional regulation of different seed storage proteins. The goal of this study has been (i) to define a framework of seed development, (ii) to identify TFs potentially involved in the filling phase, (iii) and to validate their role with the model legume Medicago truncatula and evaluate their influence on the pea seed quality (Pisum sativum). Firstly, an overview of the expression of 51k genes during seed development allowed us to identify seven key stages of seed development and corresponding molecular processes. These stages have been chosen for the profiling of 712 TFs using qRT-PCR. Out of these, 170 TFs showed differential expression during seed development. These have been divided into functional groups associated with late embryogenesis, the transition between embryogenesis and seed filling, the synthesis of vicilin, legumin A, legumin K and finally the desiccation processes. Secondly, we focused on the role of the transcription factor, LEAFY COTYLEDON1-LIKE (L1L) in legumes. Our results showed that in M. Truncatula and P. Sativum, L1L genes were expressed preferentially at the transition between embryogenesis and seed filling. Mutant analyses in both species indicated a negative role of this gene in seed storage protein accumulation, with a possible antagonistic role to that of LEC1. A sequence polymorphism of PsL1L correlated with grain weight, suggesting the fundamental role of the gene L1L in determining legume seed quality.