Abstract: The effect of DNA methylation inhibitor ( 5-azacytidine, 5-azaC) to chrysanthemum (Dendranthem a ×grandiflorum ) has been studied by the method of in vitro treatment. The results indicated that 500μmol·L - 1 of 5-azaC caused death, above 100μmol·L - 1 of 5-azaC inhibited the materials’development. The multiple buds differentiation of chrysanthemum was inhibited by every concentration of 5-azaC and the inhibiting effect of 5-azaC has time and dose additive effect. 5-azaC treatment at low concentration induced
the flowering early, this effect were stability and could be inherited through asexual multiplication. The results of MSAP (methylation sensitive amplified polymorphism technique) indicated that, the genomic of treated materials DNA methylation decreased distinctly. Part of the sites kept demethylation status in the successive transfer culture when 5-azaC removed.