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Huang, F.-Y., Department of Biology, University of Massachusetts, Amherst, MA 01003, United States
Philosoph-Hadas, S., Dept. Postharvest Sci. Fresh Produce, Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel
Meir, S., Dept. Postharvest Sci. Fresh Produce, Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel
Callaham, D.A., Department of Biology, University of Massachusetts, Amherst, MA 01003, United States
Sabato, R., Dept. Postharvest Sci. Fresh Produce, Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel
Zelcer, A., Department of Plant Genetics, Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel
Hepler, P.K., Department of Biology, University of Massachusetts, Amherst, MA 01003, United States
The ability to maintain the cytoplasmic Ca2+ concentration ([Ca2+](cyt)) at homeostatic levels has been examined during leaf senescence in detached parsley (Petroselinum crispum) leaves. Fluorescence ratiometric imaging of mesophyll cells isolated from parsley leaves at various senescence stages and loaded with the Ca2+ indicator fura-2 has revealed a distinct elevation of [Ca2+](cyt), which was positively correlated with the progress of leaf senescence. This initial increase of [Ca2+](cyt), which was first observed in cells isolated from 3-d-senescent leaves, occurred I d before or in parallel with changes in two established senescence parameters, chlorophyll loss and lipid peroxidation. However, the [Ca2+](cyt) elevation followed by 2 d the initial increase in the senescence-associated proteolysis. Whereas the [Ca2+](cyt) of nonsenescent cells remained at the basal level, the elevated [Ca2+](cyt) of the senescent cells was a long-lasting effect. Experimental retardation of senescence processes, achieved by pretreatment of detached leaves with the cytokinin benzyladenine, resulted in maintenance of homeostatic levels of [Ca2+](cyt) in cells isolated from 3-d-senescent leaves. These observations demonstrate for the first time to our knowledge a correlation between elevated [Ca2+](cyt) and the process of senescence in parsley leaves. Such senescence-associated elevation of [Ca2+](cyt), which presumably results from a loss of the cell's capability to extrude Ca2+, may serve as a signal inducing subsequent deteriorative processes.
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Increases in cytosolic Ca2+ in parsley mesophyll cells correlate with leaf senescence
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Huang, F.-Y., Department of Biology, University of Massachusetts, Amherst, MA 01003, United States
Philosoph-Hadas, S., Dept. Postharvest Sci. Fresh Produce, Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel
Meir, S., Dept. Postharvest Sci. Fresh Produce, Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel
Callaham, D.A., Department of Biology, University of Massachusetts, Amherst, MA 01003, United States
Sabato, R., Dept. Postharvest Sci. Fresh Produce, Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel
Zelcer, A., Department of Plant Genetics, Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel
Hepler, P.K., Department of Biology, University of Massachusetts, Amherst, MA 01003, United States
Increases in cytosolic Ca2+ in parsley mesophyll cells correlate with leaf senescence
The ability to maintain the cytoplasmic Ca2+ concentration ([Ca2+](cyt)) at homeostatic levels has been examined during leaf senescence in detached parsley (Petroselinum crispum) leaves. Fluorescence ratiometric imaging of mesophyll cells isolated from parsley leaves at various senescence stages and loaded with the Ca2+ indicator fura-2 has revealed a distinct elevation of [Ca2+](cyt), which was positively correlated with the progress of leaf senescence. This initial increase of [Ca2+](cyt), which was first observed in cells isolated from 3-d-senescent leaves, occurred I d before or in parallel with changes in two established senescence parameters, chlorophyll loss and lipid peroxidation. However, the [Ca2+](cyt) elevation followed by 2 d the initial increase in the senescence-associated proteolysis. Whereas the [Ca2+](cyt) of nonsenescent cells remained at the basal level, the elevated [Ca2+](cyt) of the senescent cells was a long-lasting effect. Experimental retardation of senescence processes, achieved by pretreatment of detached leaves with the cytokinin benzyladenine, resulted in maintenance of homeostatic levels of [Ca2+](cyt) in cells isolated from 3-d-senescent leaves. These observations demonstrate for the first time to our knowledge a correlation between elevated [Ca2+](cyt) and the process of senescence in parsley leaves. Such senescence-associated elevation of [Ca2+](cyt), which presumably results from a loss of the cell's capability to extrude Ca2+, may serve as a signal inducing subsequent deteriorative processes.
Scientific Publication
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