3.4 Effects of nano-Se application on flavone compounds and phenolic acids in wheat seedlings.
Flavone compounds and phenolic acids play an important role in plants to defense against pests and disease (Czerniewicz, Sytykiewicz, Durak, Borowiak-Sobkowiak, & Chrzanowski, 2017). In general, the concentration of flavone compounds and phenolic acids increased with nano-Se treatment, especially at the application rate of 5.0 mg/L (Figure 4). The flavone compounds measured in this study included quercetin, luteolin, apigenin, rutin, kaempferol and myricetin which all increased to varying degrees after application of nano-Se. Among these compounds, luteolin demonstrated the greatest increase, increased by 1.7 times, 1.3 times, and 1.1 time after the application of nano-Se at 1.0, 5.0, and 20.0 mg/L. Nano-Se (5mg/L) increased apigenin, quercetin, and rutin levels by 100.0, 14.5, and 22.2%, respectively. However, kaempferol and myricetin levels were unchanged across nano-Se treatments.
As for the phenolic acids, compared to the controls, nano-Se (5.0mg/L) applied could increase the caffeic acid, hydroxy-3, 5-dimethoxycinnamic acid, 4-hydroxybenzoic acid, 4-hydroxycinnamic acid, and chlorogenic acid levels by 74.9, 73.6, 98.0, 38.0, and 14.7%, respectively. However, the ferulic acid, syringic acid, and vanillin acid contents have non-obvious change. The results indicate that the application of nano-Se at 5.0 mg/L could invoke the changes in the concentration of plant secondary substances in wheat seedlings.
3.5 Effects of significant difference of exogenous onS. avenae growth.
As shown in Figure 5 A, compared to control, aphid number reduced by 42.9 % (nano-Se5), 35% (MT10), and 52.2% (the combination of nano-Se5 and MT10), respectively. The nano-Se application increased the DIMBOA, MT, and JA concentration by 31.1%, 57.0%, and 43.6% respectively. The MT application enhanced DIMBOA, MT, and JA levels by 31.8%, 62.8%, and 38.2%, respectively. The combined application of nano-Se5 and MT10 enhanced the DIMBOA, MT, and JA concentration by 34.8%, 70.8%, and 51.3%, respectively. The SA contents decreased by 42.2%, 37.3%, and 57.5% when treated with nano-Se, MT, and their combination (Figure 5B).
The expressions of DIMBOA (TaBx1A , TaBx3A , TaBx4A ) and MT (TaASMT2, TaCOMT ) related genes were determined (Figure 5C). Compared to the control, TaBx1A (254.7%), TaBx3A(40.0%), TaBx4A (55.9%), TaASMT2 (34.1%), andTaCOMT (12.3 times) were increased by nano-Se5. MT10 promote the expression of TaBx1A (200.7%), TaBx3A (2.0%),TaBx4A (23.7%), TaASMT2 (8.4%), and TaCOMT(7.5 times). Their combination treatment increased the expression ofTaBx1A , TaBx3A , TaBx4A, TaASMT2 and TaCOMTby 405.2%, 52.5%, 103.4%, 52.3% and 25.3 times, respectively.