High levels of the cytokinin BAP induce PCD by accelerating senescence

• Published in: Plant science (Limerick) Vol. 166; no. 4; pp. 963 - 969
• Main Authors: Carimi, Francesco, Terzi, Mario, De Michele, Roberto, Zottini, Michela, Lo Schiavo, Fiorella
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier Ireland Ltd 01.04.2004; Elsevier Science
• Subjects: 6-benzylaminopurine; apoptosis; Arabidopsis thaliana; benzyladenine; Biological and medical sciences; carrots; cultured cells; Cysteine protease gene; cytokinins; Daucus carota; Fundamental and applied biological sciences. Psychology; Growth regulators; in vitro regeneration; micropropagation; Plant cell suspension cultures; Plant physiology and development; Programmed cell death; SAG12; SAG12 gene; Senescence; Senescence and abscission; somatic embryos; Vegetative apparatus, growth and morphogenesis. Senescence; Senescence; Programmed cell death; SAG12; Plant cell suspension cultures; Cysteine protease gene; Growth regulators; Cysteine; Daucus carota; Growth; Arabidopsis thaliana; Gene; Cruciferae; Dicotyledones; Angiospermae; Serine endopeptidases; Omptin; Enzyme; Hypersensitivity; Plant leaf; Cytokinin; Peptidases; Hydrolases; Spermatophyta; Umbelliferae; Apoptosis
• ISSN: 0168-9452; 1873-2259
• DOI: 10.1016/j.plantsci.2003.12.016

The cytokinin 6-benzylaminopurine (BAP), if added at high dosage to plants and cultivated cell suspensions of Arabidopsis thaliana and Daucus carota, induce programmed cell death (PCD) by accelerating senescence. The Arabidopsis cells in culture express, at the end of subculturing cycle, when they start senescing, SAG12, a cysteine protease which is typically associated with leaf senescence and not found in other forms of programmed cell death (e.g. hypersensitive response). In Arabidopsis cell suspension cultures, cell death and DNA fragmentation, due to high levels of the cytokinin, is preceded by the early expression of SAG12. The perception of BAP is influenced by the physiological state of the cells: carrot embryos are resistant to the hormonal treatment whereas unorganized growing cells are not. The possibility of using suspension cell cultures as a model system for studying senescence is discussed.