2013 ASHS Annual Conference

Changes of cold hardiness were estimated in the shoots of two peach seedlings (Prunus perisica cvs. Daewol and Kiraranokiwami) during repeated experimental deacclimation and reacclimation. In addition, changes of dehydrins by SDS-PAGE and their related gene expressions by a quantitative real-time RT-PCR were examined to find out the relationship with cold hardiness. During the first deacclimation, relative electrolyte leakage (REL) values of two cultivars increased more than each control, indicating that their cold hardiness declined. When deacclimated two cultivars were reacclimated first, REL values, indicating that their cold hardiness was regained, decreased. And then, REL values of two cultivars reexposed to warm temperature by the second deacclimation increased more than those of the first deacclimation, and ‘Kiraranokiwami’ was entirely deacclimated. After that, when ‘Daewol’ was reexposed to low temperature by the second reacclimation, REL values of ‘Daewol’ increased more than those of the first reacclimation. Finally, ‘Daewol’ was entirely deacclimated by the third deacclimation treatment. Changes of dehydrins and their gene expressions (PpDhn1, PpDhn2, and PpDhn3), also positively correlated with changes of cold hardiness throughout the experiments. Our results indicate that recent repeated warm spells may cause premature deacclimation in late winter and early spring, and ‘Daewol’ may be more flexible to freezing injury caused by unstable temperature conditions.