Chilling-Dependent Release of Seed and Bud Dormancy in Peach Associates to Common Changes in Gene Expression

Abstract

Reproductive meristems and embryos display dormancy mechanisms in specialized structures named respectively buds and seeds that arrest the growth of perennial plants until environmental conditions are optimal for survival. Dormancy shows common physiological features in buds and seeds. A genotype-specific period of chilling is usually required to release dormancy by molecular mechanisms that are still poorly understood. In order to find common transcriptional pathways associated to dormancy release, we analyzed the chilling-dependent expression in embryos of certain genes that were previously found related to dormancy in flower buds of peach. We propose the presence of short and long-term dormancy events affecting respectively the germination rate and seedling development by independent mechanisms. Short periods of chilling seem to improve germination in an abscisic acid-dependent manner, whereas the positive effect of longer cold treatments on physiological dwarfing coincides with the accumulation of phenylpropanoids in the seed.

Effects of Fluridone Treatment on Seed Germination and Dormancy-associated Gene Expression in an Ornamental Peach (<i>Prunus persica</i> (L.) Batsch)

“…(1977) found that short stratification promoted the production of morphological lesions on peach leaves. An in vitro culture experiment on peach seeds showed that seedlings grew with a dwarf phenotype when the chilling time was insufficient (Leida et al, 2012). These results suggest that chilling seeds at 5°C for 2 weeks was not enough to avoid dwarfism and lesions in this study.…”

“…In a previous study, LeMADS were also significantly repressed during chilling treatment of peach embryos (Worarad et al, 2016). Similarly, the expressions of DAM1 and DAM6 that are in the DORMANCY AS-SOCIATED MADS-box (DAM) group were decreased significantly by chilling treatment in peach seeds (Leida et al, 2012), suggesting that MADs box genes are associated with release of seed dormancy by stratification in mechanisms of transcriptional regulation. Furthermore, most of the genes encoding LEA proteins have been shown to contain ABA response (ABRE) and/or low temperature response (LTRE) elements in their promoters, and many of these genes are induced by ABA, cold, or drought stress (Hundertmark and Hincha, 2008).…”

“…As described above, dry seeds started to germinate with the uptake of water by imbibition and seeds of most Prunus species require a period of low temperature to break seed dormancy and allow normal growth (Chang and Werner, 1983;Leida et al, 2012;Suszka et al, 1996). In this study, we applied fluridone and moist chilling to peach seeds and determined the germination, ABA content, and expressions of the seven ABA-related genes.…”

“…5F). Similarly, the transcript levels of DAM1 and DAM6 were downregulated during dormancy release in seeds of two different peach cultivars (Leida et al, 2012). Chilling accumulation has been postulated as the major input conditioning seasonal fluctuations in the expression of MADS-box genes in peach buds .…”

“…In general, dry seeds start to germinate with the uptake of water by imbibition, followed by embryo expansion. Seeds of most Prunus species require a period of chilling to break seed dormancy and allow normal growth (Chang and Werner, 1983;Leida et al, 2012;Suszka et al, 1996). In peaches, when the cold treatment is insufficient, seedlings show physiological dwarfing which is considered a special case of embryo dormancy (Bewley and Black, 1982).…”