The Role of Vertical Transmission of Shoot Endophytes in Root-Associated Microbiome Assembly and Heavy Metal Hyperaccumulation in Sedum alfredii

The transmission mode of shoot-associated endophytes in hyperaccumulators and their roles in root microbiome assembly and heavy metal accumulation remains unclear. Using 16S rRNA gene profiling, we investigated the vertical transmission of shoot-associated endophytes in relation to growth and Cd/Zn accumulation of Sedum alfredii (Crassulaceae). Endophytes were transmitted from shoot cuttings to the rhizocompartment of new plants in both sterilized (γ-irradiated) and native soils. Vertical transmission was far more efficient in the sterile soil and the transmitted endophytes have become a dominant component of the newly established root-associated microbiome. Based on 16S rRNA genes, the vertically-transmitted taxa were identified as the families of Streptomycetaceae, Nocardioidaceae, Pseudonocardiaceae, and Rhizobiaceae. Abundances of Streptomycetaceae, Nocardioidaceae and Pseudonocardiaceae were strongly correlated with increased shoot biomass and total Cd/Zn accumulation. Inoculation of S. alfredii with...