Figure 5.
Enhanced pathogen-induced PCD in transgenic tobacco plants with reduced catalase (AS1). (A) A protein blot showing that PR-1 protein does not accumulate in AS1 plants growing under controlled conditions. PR-1 expression is shown to be induced after infection of plants with bacteria (P. syringae pv. phaseolicola, NPS3121; OD600 = 0.1). (B) A graph showing enhanced HR cell death in AS1 plants infiltrated with different concentrations of bacteria compared with wild-type plants infiltrated with the same amount of bacteria. (C) Cell death induced in AS1 plants by a low titer of bacteria is accompanied by fragmentation of nuclear DNA. Wild-type and AS1 plants were infiltrated with a high (OD600 = 1) or low (OD600 = 0.1) titer of bacteria. At 18 h postinfection total DNA was extracted from duplicate leaf samples and DNA fragmentation was assayed by FIGE. (D) Rapid development of necrotic lesions in AS1 plants in response to infiltration with the bacterial pathogen P. syringae pv. tabaci. Wild-type and AS1 plants were infiltrated with water (Mock) or P. syringae pv. tabaci (OD600 = 1) and photographed 18 h after inoculation. An OD600 of 1.0 is the equivalent of 500,000 cfu/ml.