Texture Dependency of Arbuscular Mycorrhiza-induced Plant Drought Tolerance

水是地球上所有生命的基础，在人类世，水的可用性应该会随着时间和空间的变化而改变。具体的知识差距阻碍了对植物根系、土壤微生物和土壤水力特性之间相互作用的全面机制理解。因此，本提案汇集了三个互补团队的专业知识，量化土壤干燥时土壤-植物（番茄）水分关系中土壤质地和丛枝菌根真菌（AMF）菌丝之间的相互作用。该项目由三个密切相关的工作包（WP）组成。WP1研究AMF如何影响(i)植物光合作用，（ii）宏观和孔隙尺度的土壤水力特性，以及（iii）植物对水和磷的动员。同步加速器x射线计算机断层扫描和稳定（氘）和放射性（氚，32P, 33P）同位素标记将用于土壤质地和湿度的梯度。在WP2中，一个自动化的根压室将被用来研究在一系列土壤湿度和质地下蒸腾和木质部水势之间的关系。此外，我们采用碳（13C）和流动氮（15NO3-）同位素标记和示踪来研究干旱条件下AMF对植物与土壤之间资源通量的影响。这种资源交换的空间洞察将通过在斑驳分布的土壤纹理中耦合中子层析成像和13C标记来获得。WP3利用以往WPs的实验数据开发AMF侵染模块，用于功能-结构植物模型，量化AMF对根构型和生长的影响。通过AMF、根系和土壤水力特性之间的反馈，模拟植物水分和养分的吸收，并动态量化它们的通量。在此基础上，对植物通过根系和AMF吸收资源的碳投资进行了量化。因此，该项目将大大提高我们对世界性AMF如何在不同土壤质地中赋予寄主植物耐旱性的理解。

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.