Figure 4.
Prf overexpression leads to the activation of markers of SAR. (a) Plants that overexpress Prf constitutively express PR1 and PR2. The blot containing total RNA was sequentially probed with PR1, PR2, and an 18S rDNA probe as a loading control. Wild-type plants were induced for defense gene expression by vacuum infiltration with P. s. tomato DC3000 at a concentration of 1 × 107 cfu/ml and tissue collected from inoculated leaves 7 hr later. I1/I2-, insert 1 and insert 2, silenced for Prf; I1/I2, insert 1 and insert 2; and I2, insert 2. (b) Levels of free and total salicylic acid in axenically grown plants. Data points represent the mean of two replicates ±SD. WT-DC3000, wild-type plant induced for SAR. (c) The reduction in salicylic acid levels caused by NahG eliminates the enhanced resistance to P. s. tomato T1 in I2 plants. Data points represent the mean of three replicate experiments ±SD.