Relationship between DNA methylation and ethylene in plants: A review.

DNA methylation, as a central mechanism of epigenetic regulation, plays a key role in coordinating plant growth and stress responses. Simultaneously, the gaseous phytohormone ethylene is also a crucial regulator in these processes. Both form a metabolic competition through S-adenosyl-L-methionine (SAM) and mutually regulate each other at the level of gene expression. Studies demonstrate that DNA methylation functions to either enhance or block ethylene synthesis and ethylene signal transduction, thereby regulating a spectrum of developmental processes including seed development, root growth, flower opening and senescence, flower sex differentiation, and fruit maturation. Conversely, ethylene acts to reprogram DNA methylation patterns to accelerate seedling development, leaf senescence, fruit ripening, and abscission. Under abiotic stresses, alterations in DNA methylation affect the ethylene pathway, thereby enhancing plant tolerance to cold, heat, herbicides, sulfur dioxide, and salinity. During pathogen infection, DNA methylation enhances ethylene biosynthesis and signalling, thereby reinforcing disease defence mechanisms. Additionally, studies have shown that DNA methylation regulates the ethylene pathway in processes such as embryonic development, domestication, fruit softening, and the accumulation of aromatic compounds and pigments. Although there still exist unclear specific effects and causal mechanisms concerning DNA methylation and ethylene, the current knowledge we summarized may provide new insights into ethylene and epigenetic modification in plants.