RNAi efficiency test
After finishing the vitro transcription, we put the adult P. striolata into glass bottles for doing the RNAi efficiency test.
Fig.5-1 Adult P. striolata and Brassica chinensis leaves were placed in the glass bottles. The solutions of siRNA/shRNA (10 ng/mL) were separately sprayed onto the leaves of Chinese cabbage every third day, each solution has two repeats. Around twenty adult beetles of P. striolata were tested per siRNA/shRNA sample.
Table 5-1 RNAi efficiencies of siRNA/shRNA
Fig. 5-2 The survival rate of Phyllotreta striolata at different days after siRNA/ shRNA treatment.
Fig. 5-3 Comparison of RNAi efficiencies between siRNA and shRNA
Fig. 5-4 Comparison of RNAi efficiencies between different shRNAs
Table 5-2 The effect of nucleotide content of shRNA on RNAi efficiency
By comparing the different degrees of decreasing survival rates, between siRNA and shRNA (Fig. 5-2), and between different shRNAs (Fig. 5-3), the RNAi efficiency had been showed. Results show that all the samples tested, except ALR-siRNA-1, and AlR-shRNA-1, could trigger RNAi mechanism, which was demonstrated by the survival rate decrease after treatment (Table 5-1, Fig. 5-1). After 11 days of treatment, there was a slight decrease of survival rate in water treatment (100% to 94%), in ALR-siRNA-1 (100%-81%) and in ALR-shRNA-1(100%-100%). The survival rate decrease of other treatments are significant (between 34.5%-85%). The differences of RNAi efficiency between siRNA and its corresponding shRNA, which have the same target site, are not significant (Fig. 5-2). But the nucleotide content of siRNA/shRNA seems play a role in RNAi efficiency (Fig. 5-3). When the antisense strand of the siRNA/shRNA has a weak base pairing at 3′-end (presence of A/U), but a strong base pairing at 5′-end (presence of G/C), such as ALR-siRNA-1 and ALR-shRNA-1 (Table 5-3), the RNAi efficiency of this siRNA/shRNA is very low. This result may be caused by the failure of the antisense strand to be loaded into RNA-induced silencing complex (RISC), due to the lower free energy level at the 5’end comparing to that at the 3’end.