AUTHOR=Yonekura Madoka , Aoki Naohiro , Hirose Tatsuro , Onai Kiyoshi , Ishiura Masahiro , Okamura Masaki , Ohsugi Ryu , Ohto Chikara 

TITLE=The promoter activities of sucrose phosphate synthase genes in rice, OsSPS1 and OsSPS11, are controlled by light and circadian clock, but not by sucrose

JOURNAL=Frontiers in Plant Science

VOLUME=4

YEAR=2013

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2013.00031

DOI=10.3389/fpls.2013.00031

ISSN=1664-462X

ABSTRACT=<p>Although sucrose plays a role in sugar sensing and its signaling pathway, little is known about the regulatory mechanisms of the expressions of plant sucrose-related genes. Our previous study on the expression of the sucrose phosphate synthase gene family in rice (<italic>OsSPS</italic>s) suggested the involvement of sucrose sensing and/or circadian rhythm in the transcriptional regulation of <italic>OsSPS</italic>. To examine whether the promoters of <italic>OsSPS</italic>s can be controlled by sugars and circadian clock, we produced transgenic rice plants harboring a promoter–luciferase construct for <italic>OsSPS1</italic> or <italic>OsSPS11</italic> and analyzed the changes in the promoter activities by monitoring bioluminescence from intact transgenic plants in real-time. Transgenic plants fed sucrose, glucose, or mannitol under continuous light conditions showed no changes in bioluminescence intensity; meanwhile, the addition of sucrose increased the concentration of sucrose in the plants, and the mRNA levels of <italic>OsSPS</italic> remained constant. These results suggest that these <italic>OsSPS</italic> promoters may not be regulated by sucrose levels in the tissues. Next, we investigated the changes in the promoter activities under 12-h light/12-h dark cycles and continuous light conditions. Under the light–dark cycle, both <italic>OsSPS1</italic> and <italic>OsSPS11</italic> promoter activities were low in the dark and increased rapidly after the beginning of the light period. When the transgenic rice plants were moved to the continuous light condition, both P<sub><italic>OsSPS1</italic></sub>::<italic>LUC</italic> and P<sub><italic>OsSPS11</italic></sub>::<italic>LUC </italic>reporter plants exhibited circadian bioluminescence rhythms; bioluminescence peaked during the subjective day with a 27-h period: in the early morning as for <italic>OsSPS1</italic> promoter and midday for <italic>OsSPS11</italic> promoter. These results indicate that these <italic>OsSPS</italic> promoters are controlled by both light illumination and circadian clock and that the regulatory mechanism of promoter activity differs between the two <italic>OsSPS</italic> genes.</p>