Light-Induced Circadian Expression of Starch Granule-Bound Starch Synthase Gene in Cell Suspension Cultures of Sweet Potato
Resource
TAIWANIA 44 (2): 202-211
Journal
TAIWANIA
Journal Volume
44
Journal Issue
2
Pages
202-211
Date Issued
1999
Author(s)
Abstract
Attempts were made to evaluate whether suspension cell cultures of sweet potato could be used as a tool for studying gene expression controlled by circadian clocks. Starch granule-bound starch synthase (GBSS) gene, which exhibited a circadian rhythm in the leaf tissue but expressed constantly in dark-adapted cell cultures, was used as a marker gene for the study. Because light is considered as a major signal to set circadian clocks, dark-adapted cells were entrained by 16 h light/8 h dark photoperiod for 7 days before determination for the expression of GBSS gene. Results of RNA blot analysis showed that fluctuations of GBSS mRNA during a diurnal cycle could be induced in cell cultures and the pattern of rhythm was similar to that of the leaf tissue. In addition to light effect, other environmental factors such as osmotic stress were also evaluated. Expression of GBSS gene was enhanced by 600 mM sorbitol in the dark-adapted cells; however, the pattern of circadian rhythm established under 16 L/8 D photoperiod was repressed by the high osmotic effect. These results not only indicate that the circadian clock could be set by light but also provide evidence that suspension cells might be used for studying the regulation of circadian rhythm.
Type
journal article
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