Glycine Betaine as an Osmolyte for Plant Protection Against Abiotic Stress: A Comprehensive Review

Abstract

Plants are constantly exposed to various stresses, both biotic and abiotic, which inhibit plant growth and development. Plant responses to these stresses involve specific resistance mechanisms. These mechanisms are linked to the presence of sugars and proline, which are recognized as key metabolites associated with stress conditions. Furthermore, a non-toxic compound, glycine betaine (GB), mitigates the effects of stress in some plants. Plant cells respond to abiotic stress factors by accumulating GB in the cytoplasm. Signaling molecules such as jasmonic acid and methyl jasmonates are responsible for initiating stress-mediated GB production. The resilience mechanism refers to the enhanced ability of plants to adapt to various environmental stressors, reflecting their capacity to retain information about these environments. Plant resistance to drought and salinity stress relies on sustained GB accumulation in plant cells, even after the stress conditions have stabilized or ceased. GB is more advantageous than any other osmoprotectant, such as sugar or proline, since it is metabolically more stable. In practice, GB has been extensively applied to plant surfaces as a foliar spray to promote acclimatization and adaptability, reduce stress, and stabilize plant responses to stressful conditions. The current chapter discusses the metabolic and physiological changes induced by GB, the need for genetic transformation to introduce GB-producing genes, and the potential of these genes to enhance plant stress resistance and facilitate the development of tolerance mechanisms.