Do culturable seed endophyte communities differ between native and invasive Fabaceae sharing the same habitat?

Invasive plant species threaten ecosystems by decreasing biodiversity and altering their functioning. Recent findings suggest that endophytes play a crucial role in germination and early seedling development, which may enhance plant invasion success. This study aimed to characterize the culturable seed endophytes of invasive Acacia spp. and coexisting Portuguese native Fabaceae (Erophaca baetica, Genista triacanthos, Retama monosperma, Stauracanthus genistoides and Ulex jussiaei) within two habitats: Dune and Forest. We compared seed microbial endophytes, their richness, diversity, and functional traits. Microbial communities were obtained through classical microbiology, followed by 16S rRNA and ITS region sequencing for identification. The most relevant functional traits were predicted using FAPROTAX and FungalTraits. A total of 150 isolates, 99 bacterial and 51 fungal, were identified. A distinct clustering of microbial communities was observed in Dune and Forest, indicating environment dependency. Invasive Acacia spp. had the richer and more diverse culturable microbiomes when compared with native species, acquiring a subset of microbial partners shared with natives. In Dune habitat, there was higher similarity of seed endophyte communities between Acacia and native plants than in Forest. Functional traits were more diverse in invasive than in native species, especially for bacteria; fungi had functions complementary to bacteria in all plant species. General functions were related to metabolism, biocontrol and hormonal growth promotion, which are beneficial traits that enhance germination. This study highlights the ability of Acacia spp. to acquire locally beneficial endophytes in invaded areas, which may enhance their invasion success.