Figure 1.
Leaf RWC and morphology in P. sepium seedlings during drought stress and re-watering.
Two different degrees of drought treatment, −0.4 and −1.0 MPa, were set. Plants were re-watered after being drought-stressed for 96 h under −0.4 MPa or −1.0 MPa. RWC were determined after 24 and 96 hours of Control, drought stress or re-watering. (RWC) relative water content, (A, B) RWC during drought and re-watering phase, data represent the mean ± standard deviation (SD) of three replicates. Different letters at the top of each bar indicate significant differences at P<0.01; (C-E) seedling after 96 hours of Control, −0.4 MPa and −1.0 MPa; (F-I) new buds after 96 hours of recovery from −1.0 MPa.
Figure 2.
Leaf proline biosynthesis metabolism in P. sepium seedlings during drought stress and re-watering.
Two different degrees of drought treatment, −0.4 and −1.0 MPa, were set. Plants were re-watered after being drought-stressed for 96 h under −0.4 MPa or −1.0 MPa. Parameters were determined after 0, 24 and 96 hours of drought stress or re-watering. (A) proline concentration; (B) activity of Δ1-pyrroline-5-carboxylate synthetase (P5CS); (C) activity of ornithine δ-aminotransferase (OAT). Data represent the mean ± standard deviation (SD) of three replicates. Different small letters along line of -0.4 MPa and capital letters along line of −1.0 MPa indicate significant differences between different time points at P<0.01, respectively.
Figure 3.
Stem and root proline biosynthesis metabolism in P. sepium seedlings during drought stress and re-watering.
Two different degrees of drought treatment, −0.4 and −1.0 MPa, were set. Plants were re-watered after being drought-stressed for 96 h under −0.4 MPa or −1.0 MPa. Parameters were determined after 0, 24 and 96 hours of drought stress or re-watering. (A, D) proline concentration in stems and roots; (B, E) activity of Δ1-pyrroline-5-carboxylate synthetase (P5CS) in stems and roots; (C, F) activity of ornithine δ-aminotransferase (OAT) in stems and roots. Data represent the mean ± standard deviation (SD) of three replicates. Different small letters along line of −0.4 MPa and capital letters along line of −1.0 MPa indicate significant differences between different time points at P<0.01, respectively.
Table 1.
Proline concentration, Δ1-pyrroline-5-carboxylate synthetase (P5CS) activity, ornithine δ-aminotransferase (OAT) activity and soluble protein (SP) concentration in the new buds germinated during recovery from −1.0 MPa.
Figure 4.
Leaf antioxidant defense in P. sepium seedlings during drought stress and re-watering.
Two different degrees of drought treatment, −0.4 and −1.0 MPa, were set. Plants were re-watered after being drought-stressed for 96 h under −0.4 MPa or −1.0 MPa. Parameters were determined after 0, 24 and 96 hours of drought stress or re-watering. (A-E) antioxidant enzyme acitivity; (F-J) antioxidant concentration; (A) superoxide dismutase (SOD), (B) catalase (CAT), (C) ascorbate peroxidase (APX), (D) glutathione reductase (GR), (E) peroxidase (POD), (F) total free amino acids (TFAA), (G) soluble sugars (SP), (H) anthocyanin (An), (I) total flavonoids (TF), (J) total phenols (TP). Data represent the mean ± standard deviation (SD) of three replicates. Different small letters along line of −0.4 MPa and capital letters along line of −1.0 MPa indicate significant differences between different time points at P<0.01, respectively.
Table 2.
Correlation coefficients between Pro and ten antioxidant parameters.
Figure 5.
Scree plot of variance explained by each factor of the principal component.
(PC1-PC3) the first, second and third principal component.
Figure 6.
Principal component analysis (PCA) of P. sepium leaf samples at all time points of drought and re-watering periods.
(A, C) PC1-PC2 and PC1-PC3 variables loading plots; (B, D) PC1-PC2 and PC1-PC3 samples score plots. (PC1-PC3) the first, second and third principal component; (0.4) −0.4 MPa, (1.0) −1.0 MPa, (+Pro) with 10 mM proline in stress solution, (--Pro) with 10 mM proline in recovery solution; (D24, D96) drought for 24 and 96 hours, (R24, R96) re-watering for 24 and 96 hours after 96 h drought.
Figure 7.
Significant positive correlation between leaf proline concentration and total antioxidant activity.
Table 3.
Total scores in leaf antioxidant activity of different samples.