Abstract To investigate promotion functions and interactions between TATA/CAAT boxes and darkness inducing motif YTCANTYY in pib promoter, a set of recombined binary plasmids of 3'end deleted pib promoter were constructed. Experiment results from analysis of their transgenic rice (Oryza sativa ssp. japonica) plants showed that the deletion of pib promoter fragments of TATA and CAAT boxes in 3' end remained not only their promotion activity but also their high expression in root system. The 3' deleted pib promoter harboring 2 or 4 YYTCANTYY and intact pib promoter harboring 6 YTCANTYY all possessed darkness inducing activity. After 24 h darkness treatment, GUS activities in the transgenic rice plant roots of above three recombined binary plasmids enhanced clearly and the increases of GUS activities in the stem and leaf were not obvious. These were said that the darkness inducing activity in pib promoter is mostly decided by the motif of YTCANTYY and this motif also can compensate for the missing fuction of TATA/CAAT.
