Ozone-Induced Cell Death in Tobacco Cultivar Bel W3 Plants. The Role of Programmed Cell Death in Lesion Formation

AUTOR(ES)

Pasqualini, Stefania

FONTE

The American Society for Plant Biologists

RESUMO

Treatment of the ozone-sensitive tobacco (Nicotiana tabacum L. cv Bel W3) with an ozone pulse (150 nL L–1 for 5 h) induced visible injury, which manifested 48 to 72 h from onset of ozone fumigation. The “classical” ozone symptoms in tobacco cv Bel W3 plants occur as sharply defined, dot-like lesions on the adaxial side of the leaf and result from the death of groups of palisade cells. We investigated whether this reaction had the features of a hypersensitive response like that which results from the incompatible plant-pathogen interaction. We detected an oxidative burst, the result of H2O2 accumulation at 12 h from the starting of fumigation. Ozone treatment induced deposition of autofluorescent compounds and callose 24 h from the start of treatment. Total phenolic content was also strongly stimulated at the 10th and 72nd h from starting fumigation, concomitant with an enhancement in phenylalanine ammonia-lyase a and phenylalanine ammonia-lyase b expression, as evaluated by reverse transcriptase-polymerase chain reaction. There was also a marked, but transient, increase in the mRNA level of pathogenesis-related-1a, a typical hypersensitive response marker. Overall, these results are evidence that ozone triggers a hypersensitive response in tobacco cv Bel W3 plants. We adopted four criteria for detecting programmed cell death in ozonated tobacco cv Bel W3 leaves: (a) early release of cytochrome c from mitochondria; (b) activation of protease; (c) DNA fragmentation by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling of DNA 3′-OH groups; and (d) ultrastructural changes characteristic of programmed cell death, including chromatin condensation and blebbing of plasma membrane. We, therefore, provide evidence that ozone-induced oxidative stress triggers a cell death program in tobacco cv Bel W3.

Documentos Relacionados

• Ozone-Induced Programmed Cell Death in the Arabidopsis radical-induced cell death1 Mutant1
• Jasmonic Acid Signaling Modulates Ozone-Induced Hypersensitive Cell Death
• Ethylene Insensitivity Modulates Ozone-Induced Cell Death in Birch1
• Programmed Cell Death in Plants.
• Amelioration of Ozone-Induced Oxidative Damage in Wheat Plants Grown under High Carbon Dioxide (Role of Antioxidant Enzymes).