Figure 7.

The role of LeMPK1, LeMPK2, and LeMPK3 in Cf-4-mediated HR and resistance to C. fulvum. Tomato plants were inoculated with TRV:GFP, TRV:Cf-4, TRV:LeMPK1, TRV:LeMPK2, or TRV:LeMPK3 and injected with Avr4 or challenged with C. fulvum-expressing Avr4. A, After 3 weeks, a total of 160 leaflets of the TRV-inoculated ‘Money Maker’-Cf-4 plants were injected with Avr4 protein at 10 sites. The average number of sites per leaf that developed a specific HR, visible as necrosis, is shown (see “Materials and Methods” for details). The asterisks indicate a significantly decreased response as compared to TRV:GFP-inoculated plants (P ≤ 0.05). B, ‘Money Maker’-Cf-0 plants that are fully susceptible to C. fulvum and ‘Money Maker’-Cf-4 plants that are fully resistant were inoculated with the indicated recombinant TRV VIGS constructs. After 3 weeks, the plants were inoculated with a strain of C. fulvum-expressing Avr4 and GUS and leaflets were stained for GUS activity after 14 d. Leaflets representative of five independent experiments are shown at the top and magnification of GUS-stained areas is shown at the bottom; green margins indicate compromised resistance.