Figure 4.

Activation of WIPK by TMV in tobacco plants [cv. Xanthi nc (NN)] maintained at 22°C throughout infection. (A) Increase in steady-state levels of WIPK mRNA in TMV-infected tobacco plants. Tobacco plants were inoculated with TMV or buffer (mock) as in Fig. 1 except a higher concentration of TMV was used (5 μg/ml). Leaf discs were taken at the indicated times in hr postinoculation (hpi). Total RNA was prepared and analyzed for WIPK mRNA as described in Fig. 3. (B) Increase of WIPK protein in TMV-infected tobacco maintained at 22°C. Protein extracts were prepared from duplicate leaf discs to those used in A. Twenty micrograms of protein was analyzed by immunoblotting by using Ab-p44N as described in Fig. 3. (C) Induction of WIPK enzymatic activity in TMV-infected tobacco maintained at 22°C. Selected protein extracts from B were analyzed by immune-complex kinase assay by using WIPK-specific Ab-p44N as described in Fig. 2.