Plant genetics and site properties influenced the diversity of seed endophytic bacterial communities of Odontarrhena species from serpentine soil of Albania

Aims Seed endophytic bacteria (SEB) are able to improve plant growth and to protect them against abi otic or biotic stresses. This work aimed to characterize the seed endophytic bacterial communities associated with diferent species of the nickel hyperaccumulator Odontarrhena, which is adapted to extreme environ ments such as serpentine soils. Moreover, this work also aimed to study any potential congruency between SEB community diversity and plant phylogeny. Methods Endophytic bacterial communities were characterized for seeds from 9 Odontarrhena popu lations, using high throughput sequencing. The plant genomes and environmental properties of the sites had previously been described. Results and discussion All Odontarrhena popula tions shared more than 95% of their OTUs and meta barcoding revealed a large SEB core microbiome. The plant species was more determinant than the site in explaining the dissimilarities between SEB com munities. Nonetheless, both site and Odontarrhena species factors were signifcant diversity drivers of the SEB communities and the best explanatory fac tor was the interaction between them. When focusing only on plant populations, some OTUs were over- or under-represented in the O. chalcidica SEB commu nities in comparison with the SEB communities of the 4 other Odontarrhena species. With the current genetic markers, the cophylogenetic analysis revealed a non-signifcant coherence of phylogenies between seed microbiota and corresponding host plants. The OTUs based prediction of metabolic functions, is a frst step that would potentially allow the power of the microbiome to be harnessed, thereby improv ing hyperaccumulator production in an agromining context.