Figure 4.

Exogenous spray of MeSA induced NbAGO2 expression. (A) 500 µM of MeSA was sprayed on N. benthamiana leaves and the leaves were collected at 10 h post spray. Total RNAs were isolated and NbPR1a level was determined by Northern blot experiment using NbPR1a sequence specific probe. The same blot also includes the TMV infected leaf sample after 10 h of infection. NbActin served as internal control and its mRNA level was evaluated by same way using NbActin specific probe. The number below the panel indicates the ratio of the blot band intensity between NbPR1a and NbActin, in which the ratio in first lane was arbitrarily defined as 1. (B) The same leaf tissues treated by MeSA were collected at different time points and NbAGO2 expression was determined by quantitative real-time PCR. Plants sprayed with water solution served as control treatment. NbAGO2 expression in control was arbitrarily designated as 1. N. benthamiana GAPDH gene served as the internal control. Significant differences between groups were calculated by Student’s t-test. Single asterisk indicated significant difference at p < 0.05.