Role for salicylic acid in the activation of defense responses in catalase-deficient transgenic tobacco

Transgenic tobacco plants with severely reduced catalase activity were crossed with NahG plants that do not accumulate salicylic acid. Some of the progeny from the cross spontaneously developed necrosis when grown under strong light, similar to that observed on the parental severely catalase-deficient plants. However, in contrast to the parental catalase-deficient plants, these progeny plants did not constitutively express PR-I genes or develop enhanced resistance. Thus, salicylic acid appears to be required for the induction of these defense responses in catalase-deficient tobacco plants.