Comparative metabolic profiling of Vitis amurensis and Vitis vinifera during cold acclimation

Abstract

Vitis amurensis is a wild Vitis plant that can withstand extreme cold temperatures. However, the accumulation of metabolites during cold acclimation (CA) in V. amurensis remains largely unknown. In this study, plantlets of V. amurensis and V. vinifera 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 V. amurensis, but not in Muscat of Hamburg. Twelve metabolites, including isoleucine, valine, proline, 2-oxoglutarate, and putrescine, increased in V. amurensis during CA. More galactinol, ascorbate, 2-oxoglutarate, and putrescine, accumulated in V. amurensis, but not in Muscat of Hamburg, during CA, which may be responsible for the excellent cold tolerance in V. amurensis. 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 BAMY (VIT_02s0012 g00170) and RafS (VIT_05s0077 g00840) 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 V. amurensis and V. vinifera under CA.

Fig. 1. Principal component analysis of metabolite profiles in leaves of V. amurensis and V. vinifera cv. Muscat of Hamburg.

Va V. amurensis; Vv V. vinifera cv. Muscat of Hamburg. Score plot (a) of samples and loading plot (b) of metabolites for the first two components, 1 (PC1) and 2 (PC2). Samples at 0, 24, and 72 h after cold treatment are represented by different shapes with colors. Each point represents an individual biological replicate in a (n = 6) and a single metabolite in b

Fig. 2. Metabolites with significantly different levels (P-value < 0.05, Student’s t-test) in V. amurensis (blue) and V. vinifera cv.

Muscat of Hamburg (red) under the non-cold stress condition. Metabolite levels are normalized by the means of all samples and presented as the mean ± SEM. of six biological replicates

Fig. 3. Common responding metabolites in V. amurensis and V. vinifera cv.

Muscat Hamburg under the cold stress condition. a Sugars; b amino acids; c organic acids; d others. The time points are the non-stress condition (0) and cold stress at 24 h (24) and 72 h (72). The time points are connected using solid (V. amurensis) or dotted (V. vinifera) lines. Each data point represents the average of six biological replicates with error bars representing the standard deviation. Asterisks (**) and (*) indicate significant differences between the two species at P-value < 0.01 and P-value < 0.05 (Student’s t-test), respectively.

Fig. 3. Common responding metabolites in V. amurensis and V. vinifera cv.

Muscat Hamburg under the cold stress condition. a Sugars; b amino acids; c organic acids; d others. The time points are the non-stress condition (0) and cold stress at 24 h (24) and 72 h (72). The time points are connected using solid (V. amurensis) or dotted (V. vinifera) lines. Each data point represents the average of six biological replicates with error bars representing the standard deviation. Asterisks (**) and (*) indicate significant differences between the two species at P-value < 0.01 and P-value < 0.05 (Student’s t-test), respectively.

Fig. 4. Metabolites that specifically accumulated in V. amurensis and V. vinifera cv. Muscat Hamburg under the cold stress condition.

a the metabolites that specifically accumulated in V. amurensis; b the metabolites that specifically accumulated in V. vinifera cv. Muscat Hamburg. Time points are the non-stress condition (0) and cold stress at 24 h (24) and 72 h (72). Time points are connected using solid (V. amurensis) or dotted (V. vinifera) lines. Each data point represents the average of six biological replicates with error bars representing the standard deviation. Asterisks (**) and (*) indicate significant differences between the two species at P-value < 0.01 and P-value < 0.05 (Student’s t-test), respectively

Fig. 5. qRT-PCR results for the BAMY, GolS, and RafS gene family members in V. amurensisand V. vinifera cv. Muscat Hamburg.

a BAMY; b GolS; c RafS. The time points are the non-stress condition (0) and cold stress at 24 h (24) and 72 h (72). Gene expression was normalized to the expression obtained in V. amurensis under the non-stress condition. The mean expression value was calculated from three technical replicates with three independent biological replicates (n = 3). Error bars indicate the standard error of the mean. Asterisks (**) and (*) indicate significant differences compared with the WT at P-value < 0.01 and P-value < 0.05 (Student’s t-test), respectively

Fig. 5. qRT-PCR results for the BAMY, GolS, and RafS gene family members in V. amurensisand V. vinifera cv. Muscat Hamburg.

a BAMY; b GolS; c RafS. The time points are the non-stress condition (0) and cold stress at 24 h (24) and 72 h (72). Gene expression was normalized to the expression obtained in V. amurensis under the non-stress condition. The mean expression value was calculated from three technical replicates with three independent biological replicates (n = 3). Error bars indicate the standard error of the mean. Asterisks (**) and (*) indicate significant differences compared with the WT at P-value < 0.01 and P-value < 0.05 (Student’s t-test), respectively