Changes in Cold Hardiness and P5CS Gene Expression of Four Peach (Prunus persica) Cultivars during Deacclimation

Low temperature is a crucial abiotic factor limiting geographical distribution, growth, and productivity of temperate plants. The low temperature reactions of most plants are different depending on season and stage of development. This study was conducted to investigate seasonal changes of cold hardiness by electrolyte leakage analysis and expression ofP5CS gene in field-grown peach cultivars during deacclimation. Current-year shoots from 7 - to 8-year-old deciduous peach trees (Prunus persica) of four cultivars used for this study are ‘Odoroki’, ‘Kanoiwa Hakuto’, ‘Jinmi’, and ‘Janghowon Hwangdo’. Cold hardiness of those cultivars was observed from November, 2012 to April, 2013. Cold hardiness of all cultivars gradually increased and reached maximum in December 2012 and then decreased by April 2013.Relative expression levels of P5CS gene increased steadily and reached maximum in January 2013 in ‘Odoroki’, ‘Kanoiwa Hakuto’, ‘Janghowon Hwangdo’. The seasonal pattern of expression of P5CS gene was slightly different from cold hardiness, which maximized in December 2012. On the other hands, expression of P5CS gene in ‘Jinmi’ did not appear to be seasonally regulated.