Root architecture and spatio-temporal C-exudation dynamics

Anna-Lena Prommersberger, Vergara-Sosa Manuel, Rodionov Andrei, Lehndorff Eva

P 5.5 in Open Poster Session

With regard to climate change, it is becoming increasingly important to know what influences carbon inputs and storage in soil. Since 2017, the priority program ‚Rhizosphere Spatiotemporal Organization – a Key to Rhizosphere Functions (SPP 2089)‘ conducts research on temporal and spatial interactions between roots and the surrounding rhizosphere soil. This project focuses on the influence of fine root hairs of maize roots on temporal and spatial dynamics of carbon release. We hypothesized that with fine roots C exudation reaches more efficiently, i.e. wider and faster, into soil compared to maize plants without root hairs. To test this, a genetically modified maize genotype (without root hairs) is compared with conventional maize (with root hairs). Both genotypes were raised in the same soil substrate. Subsequently, maize was labeled with 13CO2 to allow tracing of C exudation patterns. The plant exudation and microbial C turnover activity was stopped on different days after labeling (1, 2, 4 and 6 days) by freezing the pots and maize plants. This was followed by a targeted removal of partial roots within their soil matrix, which were then embedded in sodium silicate. These samples were analyzed for 13C tracer dynamics using EA-IRMS on root material, rhizosphere soil and bulk soil. Currently, samples are processed for spatial C and nutrient patterns using SEM/EDX and for micro-scale 13C dispersal using laser ablation-IRMS. Finally, we will be able to visualize the amount and distance of carbon emitted from the root in spatial-temporal resolution.

Keywords: rhizosphere, root hairs, carbon, exudates