Presumable protective role of peroxidase and polyphenol oxidase enzymes against freezing stress in peach (Prunus persica /L./ Batsch)

Abstract

Antioxidant enzymes have important roles in inactivation of the active oxygen forms induced by the different stresses. During winter, the over-wintering organs of peach are exposed to severe chilling temperatures. Our aim was to study the role of two antioxidant enzymes in the protection mechanisms against freezing injuries in three peach genotypes representing contrasting levels of cold hardiness. The activity of these two antioxidant enzymes in the different plant tissues increased during the first half, while decreased during the second half of the dormancy period. Due to the cold spells during ecodormancy the activity of antioxidant enzymes increased again in some sample. This phenomenon was mostly characteristic to the cold tolerant genotypes. In floral buds the activity of polyphenol-oxidase changed to a greater extent, while in the vegetative tissues it was the peroxidase enzyme showing a greater change. Thus to establish the exact role of antioxidant enzymes in abiotic stress tolerance requires further detailed investigations.