Differences in cold hardiness, carbohydrates, dehydrins and related gene expressions under an experimental deacclimation and reacclimation in Prunus persica

Abstract

To boost our understanding of a recent outbreak of freezing injury, we sought to confirm distinctive features between the shoot tissues of the peach (Prunus persica) cultivars Daewol and Kiraranokiwami by mimicking unseasonable changes of temperatures that occur in the early spring through repeated deacclimation and reacclimation treatments. Patterns of cold hardiness declined dramatically during the deacclimation and rose during the reacclimation in both cultivars. Our results indicated that 'Daewol' possessed higher capacity in response to repeated deacclimation and reacclimation treatments than 'Kiraranokiwami'. 'Daewol' showed more sensitive changes in the carbohydrates in response to warm and low temperatures compared with 'Kiraranokiwami'. 'Daewol' indicated almost similar repeated down- and up-patterns in soluble sugar content in response to repeated deacclimation and reacclimation, whereas it indicated repeated up- and down-patterns in starch content. However, 'Kiraranokiwami' showed a progressive increase in the soluble sugar content and a progressive decrease in starch content. Notably, patterns of accumulation of a 60-kDa dehydrin protein encoded by the PpDhn1 gene were confirmed through western blotting and paralleled fluctuations of cold hardiness in both cultivars. Expression of this dehydrin was weak in both cultivars during deacclimation but its band intensity increased during reacclimation. Changes in related genes (β-amylase, PpDhn1, PpDhn2 and PpDhn3) were positively correlated with changes in cold hardiness throughout the experiment. Our results indicate that recent repeated warm periods may cause premature deacclimation in the early spring, and that more cold-tolerant cultivar may be more resilient to freezing injury caused by unstable temperature conditions.

Proline accumulation in response to high temperature in winter-acclimated shoots ofPrunus persica: a response associated with growth resumption or heat stress?

“…One-year-old 'Daewol' peach trees, commercially grafted on wild peach seedlings, were used in this study. This cultivar was selected because in our previous studies (Shin et al 2015a(Shin et al , 2015b(Shin et al , 2015c, 'Daewol' shoots showed the most sensitive response to seasonal or abrupt changes in temperatures (transition from coldhardened to dehardened status), with accompanying changes in soluble sugars, dehydrins, and related gene expression. On 2 Feb. 2015, a total of 35 one-year-old trees were dug up from the nursery and planted in 2-L pots containing sandy loam soil and maintained outdoors (latitude 36°43′07.2″N, longitude 127°29′00.0″E) for 4 d (average temperature 0.6°C; max.…”

“…The rationale for using two HTs was as follows: we have previously demonstrated that exposure of BT plants (cold acclimated) to HT1 results in significant deacclimation, and that HT1 plants reacclimated followed by deacclimation when exposed to CT followed by another HT, i.e., HT2 (Shin et al 2015c). The loss and gain in freezing tolerance in this study was accompanied by loss and gain, respectively, in the dehydrins and related gene expression as well as carbohydrates accumulation, all of which have been linked with cold acclimation mechanisms.…”

Proline Accumulates in Response to Higher Temperatures during Dehardening in Peach Shoot Tissues

“…Cold hardiness was determined by the relative electrolyte leakage (REL) method described by Arora et al (1992) and Shin et al (2015b), with slight modification. Twenty-seven 5-cm-long shoot segments of similar diameter from 15 trees of each cultivar were randomly collected from the upper part of the current-year shoots.…”

Relationship between cold hardiness and dehydrin gene expression in peach shoot tissues under field conditions

“…3). In our other study, western-blot analysis verified that this 60-kDa protein was a dehydrin (Shin et al, 2014). On the other hand, a 30-kDa protein, assumed to be a dehydrin protein encoded by PpDhn2 , did not display any discernible changes.…”