Legumes such as pea (Pisum sativum L.) can accumulate large amounts of protein in their seeds even without nitrogen fertilizer thanks to their symbiosis with N2-fixing soil bacteria. Pea cultivation offers undeniable economic and environmental benefits in the context of a growing demand for plant proteins. The aim of this project is to elucidate the molecular processes underlying the accumulation of seed storage proteins (SSPs) in pea, focusing on the NUCLEAR FACTOR YB (NF-YB) transcription factors, including LEAFY COTYLEDON 1 (LEC1) and LEC1-like (L1L), which have been shown to be key regulators of seed development and storage compound accumulation in Arabidopsis thaliana. Phylogenetic and transcriptomic analyses identified four seed-specific NF-YB candidates for the regulation of SSP synthesis in pea, two164 of which are orthologs of the AtLEC1 and AtL1L genes. Pea mutants for these genes were obtained by TILLING (Targeting Induced Local Lesions IN Genomes), and preliminary phenotyping showed that loss of function l1l mutants are affected in seed size and seed protein composition, suggesting that L1L may regulate SSP accumulation. A transient expression system in moss (Physcomitrella patens) protoplasts (thevenin et al.,2016), was used to test the ability of these regulators to activate the promoter of genes related to storage activities.