Divergence of Dioecious Hippophae tibetana Endophytic Communities and Investigation of Their Key Driving Factors

Dioecious plant species display sexual dimorphism in terms of their morphological and physiological properties. However, little is known about the differentiation among endophytes within female versus male members of dioecious host plants. Hence, the endophyte diversity and composition of different tissues of male and female Hippophae tibetana were investigated using amplicon sequencing, and key factors driving the differences were determined. The results showed that there were divergences in endophytic diversity, community composition, connectivity and complexity of the co-occurrence network between females and males H. tibetana. The females and males owned their unique phyla of endophytic bacteria (Fusobacteriota and Chloroflexi, respectively). Significant enrichment of species at different levels was found between females and males, suggesting that these species could be potential biomarkers for male and female H. tibetana. Variance partitioning analysis (VPA) and Spearman analysis revealed that the phytostoichiometry and metabolites of H. tibetana explained more differences in community composition of fungal and bacterial endophytes than rhizosphere soil physicochemical properties, and endophytes exhibited a significant positive correlation with the phytostoichiometry and metabolites of H. tibetana. PICRUSt and FUNGuild predictive analyses revealed differences in endophytic fungal function between female and male H. tibetana, while the endophytic bacterial functions were metabolism. These results reveal the sexual differentiation of endophytes in dioecious plants and provide important knowledge for dioecious plant–microbe interactions.