The effect of low temperature on the circadian expression of nuclear genes encoding chloroplast proteins in chilling sensitive plants
Martino-Catt, Susan Jo
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Permalink
https://hdl.handle.net/2142/23532
Description
Title
The effect of low temperature on the circadian expression of nuclear genes encoding chloroplast proteins in chilling sensitive plants
Author(s)
Martino-Catt, Susan Jo
Issue Date
1991
Doctoral Committee Chair(s)
Ort, Donald R.
Department of Study
Biology, Molecular
Biology, Plant Physiology
Discipline
Biology, Molecular
Biology, Plant Physiology
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biology, Molecular
Biology, Plant Physiology
Language
eng
Abstract
Many commercially significant plants which have originated from tropical and subtropical habitats, such as tomato and corn, are quite susceptible to brief exposures to low, non-freezing temperatures. Although the effects of low temperature are often quite dramatic, the causes of the damage are quite subtle. Of the many metabolic processes affected, photosynthesis is often the most sensitive. Much research has focused on identifying sites of damage which result in the observed decrease in photosynthetic competence following low temperature exposure. The emphasis of this dissertation research was to identify possible causes of the inhibition in photosynthesis caused by dark-chilling in tomato.
We have described a technique for in vivo labelling experiments in tomato that allows a single gel to be used for autoradiography, Western blotting and Coomassie staining. Although we have optimized this system for our needs in tomato, the basic protocol should be widely applicable to other areas of research as well. We have also documented an arrest in the normal progression of the circadian rhythm which regulates expression of Cab and rubisco activase. The length of the arrest was directly proportional to the length of the low temperature treatment. The interruption in circadian expression of these genes was limited to species which are sensitive to low temperature.
Molecular studies demonstrated the dysfunction resulting in the inappropriate expression of Cab and rubisco activase following low temperature was at the level of transcriptional activity. Message levels persisted throughout the low temperature although transcriptional activity, as determined by nuclear run-on assays, was minimal. In addition to the increase in message stability, translational dysfunctions were also observed. These dysfunctions appear to be the result of a dissociation of RNA from polysomes in response to low temperature. The inappropriate expression of Cab and rubisco activase, as well as other less abundant genes, could be detrimental to the plant, perhaps resulting in the inhibition of photosynthesis.
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