Figure 4.
Ry sto ‐dependent ER is epistatic to HR and is temperature‐independent. (a) Determination of epistatic effect of ER to HR. Potato Ry sto /Ny‐1 and Ny‐1 plants were inoculated with PVYNTN . Five days after infection, symptoms of local cell death occurred only in Ny‐1 plants. The experiment was repeated three times. (b) Ry sto ‐dependent PVY resistance is not inhibited at elevated temperature. Potato Ry sto /Ny‐1 and Ny‐1 plants were inoculated with PVYNTN and divided into two groups, at 20 °C and 28 °C. Water‐treated plants were used as negative controls. Seven days after inoculation, samples of inoculated (lower graphs) and upper non‐inoculated leaves (upper graphs) were collected and PVY RNA levels were measured using qPCR. Values are expressed relative to EF1 and Sec3 reference genes and are expressed as means ± SD calculated from three biological replicates per plant line. A and C describe the names of transgenic Ry sto lines used. One‐way ANOVA with Tukey's test for statistical analysis was performed. (c) Stable transgenic N. tabacum plants carrying Ry sto under the control of a 35S promoter are resistant to PVY infection at elevated (32 °C) temperature. Seven‐week‐old N. tabacum 35S:Ry sto transgenic and non‐transformed plants were inoculated with a PVYN 205:GFP clone. Typical symptoms of PVY infection were observed 7 dpi in non‐transformed plants, whereas Ry sto lines remained symptomless. Image was taken at 14 dpi.