Identification of programmed cell death in situ in individual plant cells in vivo using a chromosome preparation technique.

A simple procedure, which combines a chromosome preparation technique with an in situ labelling technique modified from fluorescence in situ hybridization (FISH), has been developed for in situ detection of plant programmed cell death (PCD) at the single-cell level. After exposure of chromosomes and nuclei on slides by enzymolysis, Klenow or TdT was used to incorporate Bio-dUTP or fluorescein-dUTP at sites of DNA breaks. After Klenow-mediated labelling, the signals were amplified by a cascade of antigen-antibody reaction according to the detection system of FISH. This method enables in situ detection of plant PCD in vivo morphologically and biochemically at the chromosome, nuclear and DNA levels without cell culture and histological sectioning. This technique permits labelling of DNA breaks with high sensitivity due to increased chromosome and nucleus exposure to the labelling solutions, as well as due to the immunological amplification of the signals. Moreover, the changes in the cells were easier to be observed because the spatial obstacle of the cell wall and its autofluorescence were eliminated. It is potentially useful for in situ detection of PCD in plant root meristematic cells triggered by various environmental abiotic factors. It is proposed that the root tip is a versatile in vivo system for studying PCD induced by environmental abiotic factors.