Brassica napus seed microbiota

Seeds are involved in the vertical transmission of microorganisms from one plant generation to another and consequently act as reservoirs for the plant microbiota. The driving processes influencing seed microbiota assemblage have not been yet deciphered because of confounding factors related to environmental location, agricultural practices and host genotype selection.Nine genotypes were chosen among a large panel of genetically diverse Brassica napus accessions. The taxonomic structure of the seed microbiota was monitored by amplification and subsequent high-throughput sequencing of gyrB and ITS1 markers for two successive years in seed lots collected from self-pollinated plants. Seed germination capacities were compared between all seed lots.Although harvesting year was the main driver of seed microbiota composition, the host genotype was also significantly altering the structure of seed microbial assemblages. The core microbiota of B. napus included nine fungal taxa shared between all the genotypes and years, while no bacterial taxa was conserved across all genotypes and years. The harvesting year had the major effect on seed germination but with some differences between genotypes.The study demonstrates the relative contribution of host- and environmental-filtering on the assemblage of the seed microbiota. It suggests some influence of these assemblages on seed germination.