FIG 1.

Schematic representation of the experimental approach used for identifying the active microbiome associated with roots and rhizosphere soil of oilseed rape. Brassica napus seedlings were grown in pots containing organically managed soil and subjected to ¹³CO₂ pulse labeling after 4 weeks growth. Systems were harvested destructively on days 0, 1, 3, 7, and 14, and soils were analyzed for ¹³C enrichment to determine the stage at which the maximum labeled carbon was allocated to soil through rhizodeposition. Subsequently, the rhizosphere soil and root samples from that time point were used for coextraction of DNA and RNA for analyses of abundant and active bacterial and fungal microbiomes using high-throughput sequencing. ^{12 + 13}C-RNA was subjected to density gradient ultracentrifugation to separate ¹³C-RNA and ¹²C-RNA fractions that were used to characterize the active bacterial and fungal microbiomes assimilating recent ¹³C-labeled photoassimilates of plants.