## 3 Results
### S10 Induced the Expression of Defense-Related Genes in Wheat Seedlings  
To evaluate whether S10 can induce the expression of defense-related genes in wheat seedlings, the expression levels of eight genes in wheat seedlings subjected to different treatments were determined. As presented in Figure 6, SA-related genes _PR1.1, PR2, PR5_, and _PAL1_ in wheat plants inoculated with _F. granimearum_ only displayed similar patterns. Compared with the Fg group, _PR1.1_ and _PR2_ all showed a maximum expression level at 24 hpi in the S10 + Fg-treated plants and increased by 3.67- and 5.18-fold, respectively  
Figure 5: Effects of _S. pratensis_ S10 on the activities of defense-related enzymes in wheat seedlings. (**A**) Catalase (CAT) activity. (**B**) Superoxide dismutase (SOD) activity. (**C**) Peroxidase (POD) activity. (**D**) Phenylalanineammonalylase (PAL) activity. (**E**) Polyphenoloxidase (PPO) activity. Data are presented as mean \(\pm\) SE of three independent experiments consisting of three biological replicates (ANOVA, Duncan’s test). Capital letters (A, B, C) on bars indicate significant differences between different treatments at the same time, and ns indicates no statistical difference based on [PERSON]’s test (_p_ < 0.01). SDW represents wheat plants treated with sterile distilled water used as a control; S10 means the wheat seedlings were treated with S. _pratensis_ S10 only; Fg indicates the wheat seedlings that were inoculated with _F. granimearum_ only; and S10 + Fg represents the wheat seedlings that were pretreated with S10 24 h prior and then inoculated with _F. granimearum_.  
(Figure 6A,B). The _PR5_ expression in the S10 + Fg treatment group was obviously increased at 48 hpi and was 4.86-fold higher than that in the Fg group (Figure 6C). _PAL1_ reached the highest expression level at 48 hpi in the S10 + Fg treatment group, with a fold change of 1.76, in comparison with the Fg group (Figure 6D). Additionally, with the JA/ET-related genes _PR3_, _PR4a_, and _PR9_, the overall dynamics of _PR3_ expression were similar to those of _PR4a_ expression (Figure 6E,F). The expression levels of the two genes in the S10 + Fg treatment group were all higher than those in the Fg treatment group. Remarkably, the relative expressions of genes _PR3_ and _PR4a_ both reached a maximum at 72 hpi, and the expression of _PR3_ and _PR4a_ in the S10 + Fg treatment group was 2.11- and 2.06-fold higher than in the Fg treatment group at this time (Figure 6E,F). In wheat seedlings treated with S10 + Fg, the gene _PR9_ was obviously up-regulated at all time points in comparison with the Fg treatment group (Figure 6G). The _PR9_ expression peaked at 48 hpi in the S10 + Fg treatment group, with 7.99-fold (Figures 6G). The expression of _PDF1.2_ showed a slight up-regulation in the S10 + Fg treatment group, 2.25-fold higher in comparison with that in the Fg treatment group (Figure 6H). Overall, we found that when wheat seedlings were pretreated with S10, the JA/ET and SA signaling pathways were apparently activated in wheat plants but only upon _F. graminearum_ infection. These results indicated that S10 modulated plant defense signaling pathways during pathogen infection.  
Figure 6: The expression levels of eight defense-related genes. The effects of _S. pratensis_ S10 on PR1.1 (**A**), PR2 (**B**), PR5 (**C**), PAL1 (**D**), PR3 (**E**), PR4a (**F**), PR9 (**G**), and PDF1.2 (**H**) expression in wheat seedlings. Data are presented as mean \(\pm\) SE of three independent experiments consisting of three biological replicates (_p_ < 0.05, ANOVA, Duncan’s test). Lowercase letters on bars indicate significant differences. SDW represents wheat plants treated with sterile distilled water used as a control; S10 means the wheat seedlings were treated with _S. pratensis_ S10 only; Fg indicates the wheat seedlings that were inoculated with _F. graminearum_ only; and S10 + Fg represents the wheat seedlings that were pretreated with S10 24 h prior and then inoculated with _F. graminearum_.