Abstract
BackgroundBud dormancy is a sophisticated strategy which plants evolve to survive in tough environments. Endodormancy is a key obstacle for anti-season culture of tree peony, and sufficient chilling exposure is an effective method to promote dormancy release in perennial plants including tree peony. However, the mechanism of dormancy release is still poorly understood, and there are few systematic studies on the metabolomics during chilling induced dormancy transition.ResultsThe tree peony buds were treated with artificial chilling, and the metabolmics analysis was employed at five time points after 0–4 °C treatment for 0, 7, 14, 21 and 28 d, respectively. A total of 535 metabolites were obtained and devided into 11 groups including flavonoids, amino acid and its derivatives, lipids, organic acids and its derivates, nucleotide and its derivates, alkaloids, hydroxycinnamoyl derivatives, carbohydrates and alcohols, phytohormones, coumarins and vitamins. Totally, 118 differential metabolites (VIP ≥ 1, P < 0.05) during chilling treatment process were detected, and their KEGG pathways involved in several metabolic pathways related to dormancy. Sucrose was the most abundant carbohydrate in peony bud. Starch was degradation and Embden Meyerhof Parnas (EMP) activity were increased during the dormancy release process, according to the variations of sugar contents, related enzyme activities and key genes expression. Flavonoids synthesis and accumulation were also promoted by prolonged chilling. Moreover, the variations of phytohormones (salicylic acid, jasmonic acid, abscisic acid, and indole-3-acetic acid) indicated they played different roles in dormancy transition.ConclusionOur study suggested that starch degradation, EMP activation, and flavonoids accumulation were crucial and associated with bud dormancy transition in tree peony.
Highlights
Bud dormancy is a sophisticated strategy which plants evolve to survive in tough environments
Metabolomics analysis during chilling induced dormancy transition To study the metabolic changes during chilling-induced dormancy release in tree peony, flower buds were picked at five time points after 0–4 °C treatment for 0, 7, 14, 21 and 28 d, respectively, and metabolic profiling was analyzed by ultra-performance liquid chromatography (UPLC) and tandem mass spectrometry (MS/MS) (Fig. 1a)
The results of metabolic pathway analysis showed that they were mapped to 14 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways (Fig. 1c), of them, totally 183 metabolites were assigned to the pathway of global and overview, followed by amino acid metabolism with 85, biosynthesis of other secondary metabolites numbered 82, metabolism of cofactors and vitamins numbered 33, nucleotide metabolism, carbohydrate metabolism amounted 33, and so on (Fig. 1c)
Summary
Bud dormancy is a sophisticated strategy which plants evolve to survive in tough environments. Endodormancy is a key obstacle for anti-season culture of tree peony, and sufficient chilling exposure is an effective method to promote dormancy release in perennial plants including tree peony. The bud dormancy of woody plants is a complex process that allows plants to survive in harsh environments such as cold and drought, and it is classified as paradormancy, endodormancy, and ecodormancy [1], of which endodormancy is regulated by internal factors [2]. Endodormancy has an important impact on the maintenence and producction of the plant, for instance, the anti-season cultivation of some fruit trees. In Paeonia lactiflora, low temperature accumulation at 5 °C for nine weeks was required to ensure the re-growth of buds [6]. The requirements of chilling unit are in a genotype dependent manner [8], and significantly different among apical buds, lateral buds and catkins in Persian walnut (Juglans regia L.) [9]
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