Research progress on exogenous substances and their mechanisms of action in alleviating low-temperature stress in...

Exogenous substances can enhance plant tolerance to low-temperature stress through five primary mechanisms. The rational application of these substances during early spring cold snaps and other unexpected low-temperature events at various growth stages can effectively mitigate crop damage and ensure stable yields. Low-temperature stress (LTS) is one of the main abiotic stress factors limiting plant growth and development and crop yield. It severely affects plant yield and even causes death by interfering with cell membrane stability, inhibiting photosynthesis, and causing metabolic imbalance. In recent years, exogenous substances (ESs) regulation technology has become an important research direction for improving plants' resistance to LTS due to its high efficiency and operability. Multiple ESs have been shown to effectively alleviate LTS in plants. This paper systematically reviews the research findings on 82 ESs from 121 literature sources and summarizes the molecular physiological mechanisms by which these substances alleviate LTS. The mechanisms of action mainly include the following five aspects: (1) enhancing the antioxidant defense system; (2) optimizing plant hormone balance; (3) maintaining and enhancing photosynthetic efficiency; (4) accumulating osmoprotective substances; (5) improving plant nutritional status. In addition, we explored in depth how to effectively utilize exogenous substances with potential and efficiency to address the challenges posed by LTS in agricultural production. This paper summarizes the research progress on the mechanisms of exogenous substances in resisting LTS, providing theoretical basis and technical support for crop cultivation and stable production in response to LTS.