Figure 6.

TMV activation of WIPK transcription in tobacco is N gene-dependent, SA-independent, and systemic. (A) WIPK mRNA induction in tobacco by TMV infection is N gene-dependent. TMV-susceptible tobacco plants [N. tabacum cv. Xanthi (nn), which lacks N resistance gene] were infected and WIPK mRNA was detected in the inoculated leaves by RNA blot analysis. (B) Induction of WIPK mRNA by TMV infection is SA-independent. Transgenic tobacco [cv. Xanthi nc (NN)] plants expressing the NahG gene were infected and WIPK mRNA was determined in the inoculated leaves by RNA gel blot analysis. (C) Increase of WIPK protein in TMV-infected NahG transgenic tobacco after temperature shift. Protein extracts were prepared from duplicate leaf discs to those used in B. Immunoblot analysis was performed as in Fig. 3. (D) Systemic induction of WIPK mRNA after TMV infection. Three leaves from each tobacco plant [cv. Xanthi nc (NN)] were either inoculated with TMV or buffer only (mock) and maintained at 22°C. At indicated days postinoculation (dpi), leaf discs were taken from the upper uninoculated leaves. Total RNA was isolated and WIPK mRNA levels were determined.