Salicylic Acid-Mediated Cell Death in the Arabidopsis len3 Mutant
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The <I>Arabidopsis lesion initiation 3</I> (<I>len3</I>) mutant develops lesions on leaves without pathogen attack. <I>len3</I> plants exhibit stunted growth, constitutively express pathogenesis-related (<I>PR</I>) genes, <I>PR-1</I>, <I>PR-2</I>, and <I>PR-5</I>, and accumulate elevated levels of salicylic acid (SA). Furthermore, <I>len3</I> is a semidominant, male gametophytic lethal mutation with partial defects in female gametophytic development. To determine the signaling pathway activated in <I>len3</I> plants, we crossed the <I>len3</I> plants with <I>nahG</I>, <I>npr1-1</I>, and <I>pad4-1</I> plants and analyzed the phenotypes of the double mutants. The <I>len3</I>-conferred phenotypes, including cell death and <I>PR-1</I> expressions, were suppressed in the double mutants. Thus SA, NPR1, and PAD4 are required for the phenotypes. However, none of these double mutants could completely suppress the <I>len3</I>-conferred stunted growth. This result suggests that an SA-, NPR1-, and PAD4-independent pathway is also involved in the phenotype. Treatment with BTH (benzo(1,2,3)thiadiazole-7-carbothioic acid), an SA analog, induced cell death in <I>len3 nahG</I> plants but not in <I>len3 npr1</I> or <I>len3 pad4</I> plants, suggesting the involvement of the PAD4-dependent but SA-independent second signal pathway in cell death in <I>len3</I> plants.
- Agricultural and Biological Chemistry
Agricultural and Biological Chemistry 70(6), 1447-1453, 2006-06-23
Japan Society for Bioscience, Biotechnology, and Agrochemistry