Chair of Root-Soil Interaction, School of Life Sciences, Technical University of Munich, Freising, Germany.
Chair of Soil Physics, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, Germany.
J Exp Bot. 2023 Sep 2;74(16):4808-4824. doi: 10.1093/jxb/erad249.
Arbuscular mycorrhizal fungi (AMF) have been presumed to ameliorate crop tolerance to drought. Here, we review the role of AMF in maintaining water supply to plants from drying soils and the underlying biophysical mechanisms. We used a soil-plant hydraulic model to illustrate the impact of several AMF mechanisms on plant responses to edaphic drought. The AMF enhance the soil's capability to transport water and extend the effective root length, thereby attenuating the drop in matric potential at the root surface during soil drying. The synthesized evidence and the corresponding simulations demonstrate that symbiosis with AMF postpones the stress onset limit, which is defined as the disproportionality between transpiration rates and leaf water potentials, during soil drying. The symbiosis can thus help crops survive extended intervals of limited water availability. We also provide our perspective on future research needs and call for reconciling the dynamic changes in soil and root hydraulics in order to better understand the role of AMF in plant water relations in the face of climate changes.
丛枝菌根真菌（AMF）被认为可以提高作物的耐旱性。在这里，我们回顾了 AMF 在从干燥土壤中为植物维持供水方面的作用以及潜在的生物物理机制。我们使用土壤-植物水力模型来说明几种 AMF 机制对植物对土壤干旱响应的影响。AMF 增强了土壤输送水的能力并延长了有效根系长度，从而减轻了土壤干燥过程中根表面基质势的下降。综合证据和相应的模拟表明，与 AMF 的共生关系推迟了土壤干燥过程中蒸腾速率与叶片水势之间不成比例的胁迫起始极限，这被定义为应力起始极限。因此，共生关系可以帮助作物在有限的水供应期内存活。我们还提供了对未来研究需求的看法，并呼吁协调土壤和根系水力的动态变化，以便更好地了解 AMF 在气候变化下对植物水分关系的作用。
