Abstract
The Arabidopsis lesion initiation 3 (len3) mutant develops lesions on leaves without pathogen attack. len3 plants express pathogenesis-related ( PR ) genes and accumulate elevated levels of salicylic acid (SA). To determine the signaling pathway, which is activated in len3 plants, we crossed the len3 plants with nahG, npr1-1, and pad4-1 plants and analyzed the phenotypes of the double mutants. The len3-conferred phenotypes, including cell death and PR expressions were suppressed in len3 nahG plants. The phenotypes of len3 npr1 and len3 pad4 plants were almost the same as those of len3 nahG plants. However, although BTH treatment could restore cell death phenotype in len3 nahG plants, but not in len3 npr1 and len3 pad4 plants. This result might suggest the involvement of the PAD4-dependent signal for the cell death in len3 plants.
