The key resistance of betaine to temperature stress in plants focuses on the low temperature layer.  The physiological needs of plants under low temperature and the efficacy of betaine against low temperature are discussed below  

Low temperature stress affects the whole physiological process of plant, such as reactive oxygen metabolism, respiration, photosynthesis and nitrogen metabolism.  The membrane system is the main location of freezing injury. The initial reaction of irreversible damage caused by temperature setback is the change of lipid molecular structure in biofilm system.  Oxygen free radicals and reactive oxygen species in plant body have strong air oxidation capacity, which can destroy the molecular structure of many microorganisms.  

Oxygen free radicals, reactive oxygen species, and antioxidant and non-antioxidant chemicals that eliminate them remain in equilibrium under all normal standards, and do not easily lead to membrane lipid peroxides within a certain low temperature range;  However, when the temperature decreases again or the delay time of low temperature increases, the production of reactive oxygen species and oxygen free radicals will increase significantly, while the elimination amount will decrease, resulting in the accumulation of oxygen free radicals, leading to membrane lipid peroxides, and then malondialdehyde (MDA), resulting in increased membrane permeability and increased electrolyte leakage, thus damaging the cytoplasmic system software.  

 Low temperature stress also reduces the compressive strength of plant photosynthesis. Existing studies have shown that low temperature stress has significant harm to the key physiological and biochemical processes of plant photosynthetic pigment components,chloroplast submicrostructure, photosynthetic energy consumption and other products.  

Effect of betaine at temperature Stress Level Some plant types accumulate betaine under low temperature stress and integrate it into low temperature to improve tolerance to freezing. Application of betaine can also improve some plant types (natural accumulation;  Betaine and non-cumulative betaine plants) 14-16.