Different respiration metabolism between mycorrhizal and non-mycorrhizal rice under low-temperature stress: a cry for help from the host

Low-temperature stress is an important environmental factor that severely disrupts plant respiration but can be alleviated by symbiotic arbuscular mycorrhizal fungi (AMF). In the current study, a pot experiment was performed to determine changes in the respiratory metabolic capacity of mycorrhizal rice (Oryza sativa) under low-temperature stress. The results demonstrated that low temperature might accelerate the biosynthesis of strigolactone in mycorrhizal rice roots by triggering the expression of genes for the synthesis of strigolactone, which acted as a host stress response signal. In addition, AMF prompted the host tricarboxylic acid (TCA) cycle by enhancing pyruvate metabolism, up-regulating the expression of genes of the TCA cycle under low-temperature stress and affecting the electron transport chain. The alternative oxidase pathway might be the main electron transport pathway in non-mycorrhizal rice under stress, while the cytochrome c oxidase (COX) pathway might be the predominant pathway in arbuscular mycorrhizal symbiosis. Mycorrhizal rice also had higher adenosine triphosphate production to maintain the natural status of respiration under stress conditions, which resulted in improved root growth status and alleviated low-temperature stress.