Reprogramming seed chromatin during germination: Insights from histone variants and modifications – SeedChrom

Seeds are essential for human food and plant dispersal. Metabolically quiescent in the dry state, the developmental transition to the germinating seedling requires important transcriptional and epigenetic reprogramming. Nucleosomes constitute the first degree of chromatin organization; however, nucleosome composition in histone variants and their histone modifications in the dry seed have not been fully characterized. Our preliminary evidence suggests that seed chromatin is enriched in specific H3 and H2B histone variants and shows particular low histone H2B ubiquitination levels. This seed-specific chromatin organization is rapidly remodeled during imbibition of the seed and interfering with variant deposition or specific histone modifications such as H2Bub results in altered seed vigor. In this project, we will combine genetic and epigenomic approaches coupled to microscopy and image analysis to dissect the seed-specific chromatin organization and to determine how this particular chromatin state is rapidly reprogrammed during seed imbibition and germination. Using screening approaches with and without a priori we will further aim to identify new actors in seed vigor.