Figure 7

Chloroxynil induced death – collapse of cells without nuclear contractions. (A) The nuclear marker line N7 was mounted in agarose, and the bromoxynil-analog chloroxynil was added to a final concentration of 500 μM and a Z-series of the hypocotyl-root junction was collected at 2 min intervals. Loss of nuclear label into the cytoplasm and a generalized loss of GFP fluorescence were followed by staining of nuclei by propidium iodide and massive cellular collapse. The shape of the nuclei remained constant throughout the experiment and did not display the characteristic contractions seen during wound induced cell death. The white asterisk identifies the same nucleus, and the green arrows to two cells in this plane of view that displayed massive plasmolysis. (B) Chloroxynil induced release of N7 marker from nucleoplasm in 12 day old N7 plants mounted in agarose and overlaid with chloroxynil to a final concentration of 500 μM. An initiating lateral root was imaged by the acquisition of Z-series at 120 sec intervals. A gradual release of nuclear label and illumination of the cytoplasm occurs without the characteristic nuclear contractions induced by wounding. Scale bars = 25 μm. Inset numbers indicate min after herbicide addition.