Texture Dependency of Arbuscular Mycorrhiza-induced Plant Drought Tolerance

• Applicants: Professor Dr. Mutez Ali Ahmed; Dr. Michael Bitterlich; Professorin Dr. Johanna Pausch; Professorin Dr. Andrea Schnepf
• Subject Area: Soil Sciences ; Plant Cultivation, Plant Nutrition, Agricultural Technology
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 516052611

Availability of water, the basis of all life on Earth, is supposed to change in space and time in the Anthropocene. Specific knowledge gaps prevent full mechanistic understanding of interactions between plant roots, soil microbes, and soil hydraulic properties. Thus, this proposal gathers the expertise of three complementary teams that quantify the interactions between soil texture and arbuscular mycorrhizal fungi (AMF) hyphae in soil-plant (tomato) water relations upon soil drying. The project is composed of three closely interrelated work packages (WP). WP1 investigates how AMF influence (i) plant photosynthesis, (ii) macroscopic and pore-scale soil hydraulic properties, and (iii) mobilization of water and phosphorus by plants. Synchrotron X-ray computer tomography and stable (deuterium) and radioactive (tritium, 32P, 33P) isotope labeling will be employed over gradients of soil textures and moistures. In WP2, an automated root pressure chamber will be utilized to investigate the relationships between transpiration and xylem water potential over a range of soil moistures and textures. Further, we employ carbon (13C) and mobile nitrogen (15NO3-) isotopic labeling and tracing to investigate resource fluxes between plants and soil as affected by AMF under drought. Spatial insights into such resource exchanges will be gained by coupling neutron tomography with 13C labelling in patchily distributed soil textures. WP3 uses the experimental data of the previous WPs for developing AMF infection module for functional-structural plant models to quantify AMF effects on root architecture and growth. Plant water and nutrient uptake will be modelled and their fluxes quantified dynamically by implementing feedbacks between AMF, root systems, and soil hydraulic properties. Based on the previous, carbon investments of plants for resource uptake via roots and via AMF are quantified. This project will thus strongly improve our understanding of how the cosmopolitan AMF confer drought tolerance to their host plants in variable soil textures.

• DFG Programme: Research Grants