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

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.

Evaluating the Effect of Light Intensity on Flower Development Uniformity in Strawberry (Fragaria ×ananassa) under Early Induction Conditions in Forcing Culture

Uniform flower development is crucial for the uniform production of mature fruit, and it is essential in the management and production of commercial strawberry (Fragaria ×ananassa) in greenhouses. Environmental factors such as temperature, light intensity, and photoperiod have been extensively evaluated to determine their roles in strawberry flower induction and growth; however, data on the role that lighting conditions play in the uniformity of flower development are still lacking. The aim of this study was to clarify the influence of light intensity on the uniformity of strawberry flower development in forcing culture. Two experiments were conducted to evaluate plants’ response to both shading and light-emitting diode (LED) treatments. Plant growth parameters (i.e., leaf area, dry matter, and number of leaves between inflorescences) and flower development data [i.e., time from flower beginning to full bloom (FB), time from transplanting to flowering (TB), and bud number (BN)] were recorded. As expected, flower development was enhanced when exposed to LED light and was delayed when shaded. Within each cultivar, a strong relationship between lighting environment and uniformity of flower development was also detected. In both experiments, TB and BN showed less variation when exposed to high light intensity compared with low intensity. This trend was true for other parameters as well, including dry matter, leaf area, and number of leaves between inflorescences. However, there were no significant differences in FB between the shading and LED treatments. The results show that strawberry growth and flower development were highly variable in a low light environment. In addition to light being an important factor in inflorescence initiation and high yield production, the results of this study also show that the amount of light supplied is an important factor in maintaining uniform flowering in forcing culture.