Linking root carbon partitioning and root traits to inter-kingom microbial variation in the maize rhizosphere. Linking root carbon partitioning to interkingdom microbial variation

This study aimed to link the maize root photoassimilate level to the rhizosphere microbial colonization in high spatial resolution and across microbial kingdoms (bacteria, fungi and protists). A 11CO2 labelling experiment was conducted with 6, 13 and 21 day old maize plants. Pathways of 11C carbon tracer, hereafter referred to as freshly assimilated carbon, were tracked by PET to collect information on maize root carbon partitioning. Simultaneously, root system development was monitored by MRI. A co-registration of PET and MRI scans in 3D enabled image-guided sampling of the rhizosphere, where we could specifically target areas with distinct carbon patterns and distinguish between all relevant root types and age classes. Microbial variation was examined by 16S, 18S and ITS amplicon sequencing.Root carbon was not uniformly distributed between roots. C-allocation patterns, root type and root section explained a significant part of microbial diversity in the rhizosphere.