Metabonomic analysis reveals EMP pathway activation and flavonoid accumulation during dormancy transition in tree peony

Abstract

Background Bud dormancy is a sophisticated strategy in which plants evolved to survive in tough environments. Chilling exposure is an effective method to promote dormancy release in perennial plants including tree peony, and endodormancy is a key obstacle for forcing culture of 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. Results A total of 535 small molecules were obtained in tree peony buds treated with chilling, belonging to 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, respectively. 118 differential metabolites were detected, and they involved in serveral metabolic pathways related to dormancy. Sucrose was the most abundant carbohydrate in peony bud. Starch degradation and EMP activity were enhanced during the dormancy release, according to the variations of sugar contents, related enzyme activities and key genes expression. Flavonoids synthesis and accunmulation were also promoted by prolonged chilling, which might attribute to the activated expression of PsDFR and PsANS. Moreover, the variations of phytohormones (SA, JA, ABA, and IAA) indicated they played different roles in dormancy transition. Conclusion Our study suggested that starch degradation, EMP activation, and flavonoid accumulation were crucial and associated with bud dormancy transition in tree peony.