Figure 9.

Light-dependent OsLHY protein stability in transgenic rice calli. A, Structure of OsLHY-LUC used for this experiment. B, Four distinct transgenic cell lines carrying UBQ:LUC, UBQ:OsLHY-LUC, UBQ:OsLHY(A)-LUC, and UBQ:OsLHY(5A)-LUC were grown under 12-h-light/12-h-dark conditions (12:12LD), and their LUC bioluminescence activity was monitored for 1 week under 12:12LD conditions and 3 d under constant darkness (DD) conditions. Light dependency of LUC stability was observed in UBQ:OsLHY-LUC lines. The quintuple mutations in the phosphorylation sites of OsLHY in the mOsLHY(5A) transgenic line may have resulted in loss of the light dependency of fusion protein stability in rice cells. By comparison, the Ala mutation at the Glu site in mOsLHY(A) did not greatly affect LUC activity. Similar bioluminescence profiles were reproducibly obtained. A representative result is shown.