Stressed Plants Destroy Damaged Chloroplasts | Chemical & Engineering News
Volume 93 Issue 42 | p. 23 | Concentrates
Issue Date: October 26, 2015

Stressed Plants Destroy Damaged Chloroplasts

Plant Biology: A ubiquitin ligase prompts cells to destroy organelles that govern photosynthesis
Department: Science & Technology | Collection: Life Sciences
News Channels: Biological SCENE
Keywords: oxidative stress, chloroplasts, reactive oxygen species, plant biology, drought
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This TEM image reveals a damaged chloroplast (white arrow) with its contents leaking out.
Credit: Salk Institute
A damaged chloroplast is degraded in a micrograph of Arabidopsis thaliana cells.
 
This TEM image reveals a damaged chloroplast (white arrow) with its contents leaking out.
Credit: Salk Institute

In stressful conditions such as drought and high temperature, a plant cell’s chloroplasts can become damaged and produce harmful reactive oxygen species (ROS). Researchers at the Salk Institute have uncovered that plants produce an enzyme to signal cells to degrade ROS-producing chloroplasts before they do too much damage (Science 2015, DOI: 10.1126/science.aac7444). The team led by Jesse D. Woodson and Joanne Chory first created a strain of Arabidopsis thaliana sensitive to photooxidative stress. With transmission electron microscopy the researchers observed cells degrading damaged chloroplasts, which leak out their contents. With these green organelles destroyed, young plants never became green. The researchers then bred a second mutant plant that also underwent photooxidative stress but did turn green, indicating that chloroplasts were damaged but not destroyed. A genetic screen of these plants revealed a mutation disabling an enzyme called plant U-box 4 E3 ubiquitin ligase, suggesting that chloroplast degradation depends on that enzyme acting as a stress signal. Understanding this mechanism may help scientists create better drought- or temperature-resistant plants.

 
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ISSN 0009-2347
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