Imaging plant cell death: GFP-Nit1 aggregation marks an early step of wound and herbicide induced cell death.

Abstract

BACKGROUND:

A great deal is known about the morphological endpoints of plant cell death, but relatively little is known about its sequence of events and/or its execution at the biochemical level. Live cell imaging using GFP-tagged markers is a powerful way to provide dynamic portraits of a cellular process that can in turn provide a descriptive foundation valuable for future biochemical and genetic investigations.

RESULTS:

While characterizing a collection of random GFP-protein fusion markers we discovered that mechanical wounding induces rapid aggregation of a GFP-Nitrilase 1 fusion protein in Arabidopsis cells directly abutting wound sites. Time-lapse imaging of this response shows that the aggregation occurs in cells that subsequently die 30-60 minutes post-wounding, indicating that GFP-Nit1 aggregation is an early marker of cell death at wound sites. Time-lapse confocal imaging was used to characterize wound-induced cell death using GFP-Nit1 and markers of the nucleus and endoplasmic reticulum. These analyses provide dynamic portraits of well-known death-associated responses such as nuclear contraction and cellular collapse and reveal novel features such as nuclear envelope separation, ER vesiculation and loss of nuclear-lumen contents. As a parallel system for imaging cell death, we developed a chemical method for rapidly triggering cell death using the herbicides bromoxynil or chloroxynil which cause rapid GFP-Nit1 aggregation, loss of nuclear contents and cellular collapse, but not nuclear contraction, separating this response from others during plant cell death.

CONCLUSION:

Our observations place aggregation of Nitrilase 1 as one of the earliest events associated with wound and herbicide-induced cell death and highlight several novel cellular events that occur as plant cells die. Our data create a detailed descriptive framework for future investigations of plant cell death and provide new tools for both its cellular and biochemical analysis.

• Authors: Sean R Cutler, Chris R Somerville
• Journal: BMC plant biology (BMC Plant Biol) Vol. 5 Pg. 4 (Mar 29 2005) ISSN: 1471-2229 [Electronic] England
• PMID: 15796778 (Publication Type: Journal Article, Research Support, U.S. Gov't, Non-P.H.S.)

Chemical References

• Arabidopsis Proteins
• Biomarkers
• Herbicides
• Nitriles
• Recombinant Fusion Proteins
• Green Fluorescent Proteins
• benzonitrile
• Aminohydrolases
• nitrilase
• bromoxynil

Topics

• Aminohydrolases (analysis, genetics)
• Arabidopsis (cytology, drug effects, physiology)
• Arabidopsis Proteins (analysis, genetics)
• Biomarkers
• Cell Death (physiology)
• Cell Nucleus (metabolism, physiology, ultrastructure)
• Endoplasmic Reticulum (metabolism)
• Green Fluorescent Proteins (genetics)
• Herbicides (toxicity)
• Imaging, Three-Dimensional
• Microscopy, Confocal
• Microscopy, Fluorescence
• Nitriles (toxicity)
• Nuclear Envelope (physiology, ultrastructure)
• Recombinant Fusion Proteins (analysis)