Fig. 3

The resistance to RSV can be improved by the increased production of MT and NO. The high disease incidence of Nipponbare inoculated with RSV can be reduced by exogenous MT and NO. The disease incidence of Nipponbare was recorded at 30 dpi pretreated with: (a) The disease incidence of Nipponbare inoculated with RSV pretreated with four different concentrations of MT (0.1, 1, 10 and 100 μM) or (b) with five different concentrations of SNP (10, 50, 100, 500 and 1000 μM) for 12 h and inoculated with viruliferous for 3 d. c The disease incidence of Nipponbare pretreated with deionized water, 10 μM MT, 100 μM SNP, 100 μM Old-SNP, 100 μM cPTIO and 10 μM MT + 100 μM cPTIO for 12 h and then inoculation with RSV for 3 d. All data were recorded at 30 dpi. Thirty plants were used for each treatment in the experiment of disease incidence. d and (e) Nipponbare plant treated with virus-free SBPH, RSV (viruliferous SBPH), 10 μM MT or 50 μM SNP. The rice plants were inoculated by virus-free SBPH or viruliferous SBPH for 3 days, then all SBPHs were removed from the plants, the time point when SBPHs were removed was set as 0 hpi. After 0, 6, 12, 18 and 24 h, plants were taken immediately for the melatonin or NO assays. All the experiments were repeated three times, and similar results were obtained. The data represent the means ± SD of triplicate measurements. Different letters or asterisks represent significantly difference at P < 0.05 according to Duncan’s multiple tests