2.2 Aphid Infestation.
Aphid (Sitobion avenae ) was
provided by Dunlun Song, College of Plant Protection, China Agricultural
University. The aphids were kept in the compartment with the relative
humidity at 50%~70%, temperature at
18~25℃, and the light intensity of 80 µmol
m-2 s-1. The nano-Se was applied in
the wheat seeding stage. Ten adults of apterous S. avenae were
then inoculated on wheat leaves after two days. Nano-Se was sprayed
every 7 days and used 3 times at all. Aphid numbers were counted every 5
days after the inoculation (only adults were counted). All experiments
were carried out on 120 mesh nylon mesh (75 × 75 ×75 cm), and there were
five nylon meshes in total. Each nylon mesh had four different
treatments (control, Se1, Se5, and Se20) with five replicates. The whole
test lasted for one month. The aphid was removed from the wheat leaves
and collected the wheat seedlings in liquid nitrogen. The samples were
stored at -80℃ before measurement for antioxidant enzymes and gene
expression.