Fig. 1: Enhanced delivery efficiency and protective effect of SPc-loaded dsRNA on leaves.

a SPc promoted the uptake of fluorescently-labelled dseGFP by P. infestans sporangia. Five μL of dseGFP (500 ng/μL) and dseGFP/SPc complex were respectively added to both P. infestans sporangia and hyphae (12 d) (10⁵ sporangia /mL), and fluorescence intensity was measured at 12 h after the incubation. (n = 3 biological replicates). b, c SPc promoted the uptake of fluorescent dseGFP by potato leaves after washing (fluorescein was used as the control). c The fluorescence intensity was measured at 12 h after the application (n = 3 leaves containing 12 inoculation points). The asterisk indicates significant difference according to independent two-tailed t-test (***p < 0.001). Bars represent the mean ± SE. d SPc promoted the uptake of fluorescently labelled dseGFP by N. benthamiana roots and leaves. The plot of the profile (right) indicates that the majority of the green fluorescence (white line) was found in the dseGFP/SPc complex-treated samples. (n = 3 biological replicates). e, f SPc increased the RNAi efficiency of the tdTomato gene in a P. infestans transformant expressing tdTomato fluorescent protein. Enlarged images of representative sporangia are shown. Five μL of dstdTomato (500 ng/μL) and dstdTomato/SPc complex were used, separately, to treat 5 μL of tdT-88069 sporangia suspension (10⁵ sporangia/mL). Both fluorescence intensity and gene expression were examined at 12 h after the treatment. The plot of the profile (right) indicates the majority of the red fluorescence (white line). Bars represent the mean ± SE. Gene expression (f) represents the comparison with the non-silenced control. (n = 3 biological replicates). The asterisk indicates significant difference according to independent two-tailed t-test (***p < 0.001). Bars represent the mean ± SE. g, h Enhanced protective effect of SPc-loaded dsRNA on potato leaves. g The detached potato leaves were sprayed with various formulations (dsRNA concentration: 500 ng/μL), and sporangia suspension was inoculated onto plant leaves after 24 h. Pictures were acquired at 2, 5 and 15 dpi, and then (h) lesion area was measured (n = 3 biological replicates). Different letters above each bar indicate significant differences at p < 0.05 as determined by one-way ANOVA with Tukey’s HSD multiple comparison post hoc test. Bars represent the mean ± SE. A five-pointed star means that the corresponding value is zero. Source data are provided as a Source Data file.