Drought is a critical factor limiting the productivity of legumes worldwide. Legumes can enter into a unique tripartite symbiotic relationship with root-nodulating bacteria of genera Rhizobium, Bradyrhizobium, or Sinorhizobium and colonization by arbuscular mycorrhizal fungi (AMF). Rhizobial symbiosis provides nitrogen necessary for growth. AMF symbiosis enhances uptake of diffusion-limited nutrients such as P, Zn, Cu, etc., and also water from the soil via plant-associated fungal hyphae. Rhizobial and AMF symbioses can act synergistically in promoting plant growth and fitness, resulting in overall yield benefits under drought stress. One of the approaches that rhizobia use to survive under stress is the accumulation of compatible solutes, or osmolytes, such as trehalose. Trehalose is a non-reducing disaccharide and an osmolyte reported to accumulate in a range of organisms. High accumulation of trehalose in bacteroids during nodulation protects cells and proteins from osmotic shock, desiccation, and heat under drought stress. Manipulation of trehalose cell concentrations has been directly correlated with stress response in plants and other organisms, including AMF. However, the role of this compound in the tripartite symbiotic relationship is not fully explored. This review describes the biological importance and the role of trehalose in the tripartite symbiosis between plants, rhizobia, and AMF. In particular, we review the physiological functions and the molecular investigations of trehalose carried out using omics-based approaches. This review will pave the way for future studies investigating possible metabolic engineering of this biomolecule for enhancing abiotic stress tolerance in plants.

干旱是限制全球豆类生产力的关键因素。豆科植物可与属的根结菌形成独特的三方共生关系根瘤菌,慢生根瘤菌， 或者中华根瘤菌以及丛枝菌根真菌（AMF）的定植。根瘤菌共生提供生长所需的氮。AMF 共生增强了对扩散限制养分（如磷、锌、铜等）以及土壤中水的吸收通过与植物相关的真菌菌丝。根瘤菌和 AMF 共生可以在促进植物生长和适应性方面发挥协同作用，从而在干旱胁迫下产生总体产量效益。根瘤菌在胁迫下生存的方法之一是积累相容性溶质或渗透剂，例如海藻糖。海藻糖是一种非还原性二糖和渗透调节剂，据报道可在多种生物体中积累。结瘤期间，类菌体内海藻糖的大量积累可保护细胞和蛋白质免受干旱胁迫下的渗透压休克、干燥和热量的影响。海藻糖细胞浓度的控制与植物和其他生物体（包括 AMF）的应激反应直接相关。然而，这种化合物在三方共生关系中的作用尚未得到充分探索。这篇综述描述了海藻糖在植物、根瘤菌和 AMF 三方共生中的生物学重要性和作用。特别是，我们回顾了使用基于组学的方法进行的海藻糖的生理功能和分子研究。该综述将为未来研究这种生物分子可能的代谢工程以增强植物非生物胁迫耐受性的研究铺平道路。