Comparative metabolic profiling of and during cold acclimation.

is a wild plant that can withstand extreme cold temperatures. However, the accumulation of metabolites during cold acclimation (CA) in . remains largely unknown. In this study, plantlets of and cv. Muscat of Hamburg were treated at 4 °C for 24 and 72 h, and changes of metabolites in leaves were detected by gas chromatography coupled with time-of-flight mass spectrometry. Most of the identified metabolites, including carbohydrates, amino acids, and organic acids, accumulated in the two types of grape after CA. Galactinol, raffinose, fructose, mannose, glycine, and ascorbate were continuously induced by cold in , but not in Muscat of Hamburg. Twelve metabolites, including isoleucine, valine, proline, 2-oxoglutarate, and putrescine, increased in during CA. More galactinol, ascorbate, 2-oxoglutarate, and putrescine, accumulated in , but not in Muscat of Hamburg, during CA, which may be responsible for the excellent cold tolerance in . The expression levels of the genes encoding β-amylase (BAMY), galactinol synthase (GolS), and raffinose synthase (RafS) were evaluated by quantitative reverse transcription-PCR. The expression () and () were primarily responsible for the accumulation of maltose and raffinose, respectively. The accumulation of galactinol was attributed to different members of GolS in the two grapes. In conclusion, these results show the inherent differences in metabolites between and under CA.