Figure 6.

Comparison of pathogen-induced PR-1 mRNA accumulation in hybrid poplar clones 245 and 388. Leaves of 8-week-old cuttings were infiltrated with either P. syringae pv maculicola KD4326 (Psm) in 10 mm MgCl₂ or mock inoculated with 10 mm MgCl₂ (Mock). Total RNA was extracted from the infiltrated area of the second through fifth fully expanded leaves, subjected to RNA-blot hybridization analysis, and the amount of hybridizing radioactivity was quantitated using a phosphor imager. Time points represent the hours after infiltration.