Background: The analytic techniques of methylation-sensitive amplification polymorphism and high-performance liquid chromatography were employed to detect variation DNA methylation of mature leaves of Chrysanthemum during the floral transition induced by short-day (SD) treatment.

Results: The time to capitulum bud appearance and early blooming from the date of planting were significantly shorter than those of the control for both an early and late-flowering cultivar. Capitulum development of the early- flowering cultivar was significantly accelerated compared with that of the control, which was different with the late-flowering cultivar. DNA methylation percentage of leaves changed dynamically during flower development. For the early-flowering cultivar, DNA methylation was 42.2%-51.3% before capitulum bud appearance and 30.5%-44.5% after capitulum bud appearance. The respective DNA methylation percentages for the late-flowering cultivar were 43.5%-56% and 37.2%-44.9%.

Conclusions: Percentage DNA methylation of leaves of Chrysanthemum decreased significantly during floral development. The decline in DNA methylation was elevated in the early-flowering cultivar compared with that of the late- flowering cultivar.