Figure 1.
Tentative biosynthesis mechanism for tricyclic aromatic quinones.
(A) Production of SEK4 and SEK4b compounds catalyzed by OKS, PKS4, and PKS5 in E. coli. (B) The chemical structures of tricyclic aromatic quinone derivatives.
Figure 2.
Kinetic analysis of Aloe vera suspension culture.
(A) Biomass accumulation of Aloe vera adventitious roots cultivated in MS liquid medium supplemented with 0.3 mg/L IBA. (B) Accumulation patterns of aloe emodin and chrysophanol in Aloe vera adventitious roots cultured on MS medium including 0.3 mg/L IBA. Each value is the mean of replicates and error bars indicate standard deviation.
Figure 3.
Effect of elicitor treatments on aloe emodin and chrysophanol production in Aloe vera adventitious roots.
Aloe emodin and chrysophanol production in Aloe vera adventitious roots treated with SA (A), MJ (B), and ethephon (C) for 24 h. Data are represented as means of replicate samples ± standard deviation. Statistical analysis was carried out using the Tukey test (* p<0.05, ** p<0.01). Asterisks indicate significant differences compared to aloe emodin and chrysophanol contents obtained from non-treated adventitious roots.
Figure 4.
Time-course analysis of aloe emodin and chrysophanol production following elicitation.
Content of aloe emodin (A, C, and E) and chrysophanol (B, D, and F) in adventitious roots and culture medium following non and elicitation with 2000 µM SA (A and B), 500 µM MJ (C and D), or 500 µM ethephon (E and F). Data are represented as means of replicate samples ± standard deviation. Statistical analysis was carried out using the Tukey test (* p<0.05, ** p<0.01). Asterisks indicate significant differences compared to aloe emodin and chrysophanol contents obtained from adventitious roots before elicitation.
Figure 5.
Alteration of primary metabolites in Aloe vera adventitious roots in response to SA.
(A) OPLS-DA of primary metabolites obtained from adventitious roots treated with 0, 500, 1000, or 2000 µM SA analyzed by GC-MS. (B) Alteration of primary metabolites associated with TCA and glycolysis in response to SA elicitation. The level of malonyl-CoA decreased in a SA dose-dependent manner. Levels of other metabolites did not change in response to SA elicitation. G6P: Glucose-6-phosphate, F6P: Fructose 6-phosphate, PEP: phosphoenolpyruvate.
Figure 6.
Effect of SA elicitation on transcript accumulation of OKS and OKSL-1.
(A) Transcript accumulation of OKS and OKSL-1 at 6 h of 0, 500, 1000, and 2000 µM SA treatment relative to that of Ubiquitin. (B) Time course analysis of gene expression of OKS and OKSL-1 in the presence of 1000 µM SA relative to that of Ubiquitin. Each value is the mean of replicates and error bars mean standard deviation. Statistical analysis was carried out using the Tukey test (* p<0.05, ** p<0.01). Asterisks indicate significant differences compared to control groups.
Figure 7.
OPLS-DA score plots of control (black), 500 µM SA (red), 1000 µM SA (blue), and 2000 µM SA (green)-treated adventitious roots analyzed by UPLC-ESI-MS in positive (A) and in negative (B) mode.
Table 1.
UPLC-ESI/MS/MS data of metabolites induced by SA treatment in Aloe vera adventitious roots.
Figure 8.
Effect of extracts from SA-treated adventitious roots on UVB-induced expression in mouse skin cells.
UVB-exposed JB6 P+ cells that were stably transfected with plasmids containing the luciferase reporter gene fused to the COX-2 promoter (A), the AP-1 gene (B), or the NF- κB gene (C) were incubated with extract from 0, 500, 1000, or 2000 µM SA-treated adventitious roots for 1 h and harvested after 4 h. Data are represented as means of replicate samples ± standard deviation. Statistical analysis was carried out with the Tukey test (* p<0.05, ** p<0.01). Asterisks indicate significant differences compared to groups treated with UVB alone. Control indicates the extract from SA-untreated adventitious roots.