Metabolomic Analysis Provides Insights into Bud Paradormancy in Camellia sinensis cv. Huangdan

Bud paradormancy has been widely studied in perennial deciduous woody species, but little attention has been paid to paradormancy set and release in perennial evergreen tree species. Here, shoot bud paradormancy in Camellia sinensis cv. Huangdan was studied by untargeted metabolomics. We found that after removing the axillary floral buds for one day, the paradormancy of the axillary shoot buds was released. The paradormant shoot buds had lower glucose-1-phosphate, fructose, and D-(-)-tagatofuranose content but higher trehalose, raffinose, galactinol, and α-D-xylopyranose content. Meanwhile, high levels of asparagine were accumulated. Flavonoids were differentially accumulated, and higher levels of three flavone glycosides (C-diglucosylapigenin, apigenin 6-C-glucoside 8-C-arabinoside, and prunin) and four proanthocyanidins (Procyanidin trimer isomer 1, Galloylprocyanidin dimer, Procyanidin trimer isomer 3, and Galloylated trimeric proanthocyanidin) were accumulated in paradormant shoot buds. During the paradormancy-to-growth transition, all these metabolites were reversed. These data suggest that the reconfiguration of carbon, nitrogen, and flavonoid metabolism could be an important aspect for the paradormancy set and release of tea axillary shoot buds. This study provided novel insights into shoot bud paradormancy set and release in a perennial evergreen tree species.