Figure 3.

The ability of DC3000 to elicit an HR and inject T3E-CyaA fusions in tobacco is inhibited by PTI. A, PTI was induced in tobacco leaves by infiltration with 3 × 10⁸ cells/mL of the DC3000 hrcC mutant 0, 2, 4, or 8 h prior to an overlapping infiltration with 2 × 10⁷ cells/mL of the wild-type DC3000 and scored for HR inhibition. The fraction to the left of each image indicates the number of times that the HR was inhibited over the total number of times the assay was performed. B, PTI was induced in tobacco leaves by infiltration of 1 μm flg21 0, 0.5, 1, or 2 h prior to infiltration with 2 × 10⁷ cells/mL DC3000 and scored for HR inhibition. C, The level of injection was determined by measuring cAMP in tobacco 7 h after infiltration with 3 × 10⁸ cells/mL of DC3000(phopU1-cyaA) in plants pretreated with hrcC or flg21 at the times indicated. D, AvrRpt2-HA is cleaved only when present inside plant cells. PTI was induced in tobacco leaves with a 1 μm flg21 treatment prior to infiltration of DC3000 containing a construct that encodes AvrRpt2-HA. In a water (mock) treatment control cleavage of AvrRpt2-HA can be detected with anti-HA antibodies, but no or reduced amounts of cleaved AvrRpt2-HA can be detected in PTI-induced tobacco tissue. Molecular mass markers in kilodaltons are indicated at the left. PTI induction inhibited the HR and the ability of DC3000 to inject HopU1-CyaA or AvrRpt2-HA into tobacco cells. Each experiment was repeated at least three times with similar results. Standard error bars are shown when appropriate.