DNA METHYLATION LEVELS AND ETHYLENE PRODUCTION IN SENESCENT, SUSPENSION-CULTURED PEAR FRUIT CELLS - IMPLICATIONS FOR EPIGENETIC CONTROL

Auxin-deprived, senescent, suspension-cultured pear (Pyrus communis cv . Passe Crassane) fruit cells that can be stimulated to produce ethyle ne were employed in the search for a possible interdependence between DNA methylation levels and ethylene production. Neither short-term sti mulation of ethylene production by CuCl2, nor longer-term stimulation by auxin, nor the inhibition of ethylene biosynthesis had a significan t effect on the cellular level of DNA methylation. However, short-term exposure to S-adenosylhomocysteine enhanced cellular ethylene product ion and long-term exposure to azacytidine resulted in the reduction of both DNA methylation levels and stress-induced ethylene production. T hese and other correlative findings, or lack thereof, are discussed in the context of ethylene physiology, DNA methylation/demethylation, an d epigenetic control.