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Rice starch branching enzyme 1 (SBE1) and granule-bound starch synthase (GBSS) catalyzed the bio-synthesis of amylopectin and amylose in rice developing en-dosperm respectively, and the genes encoding these two en-zymes, sbe1 and waxy, are mainly expressed in the en-dosperm. Within the 5 ’-upstream region of rice sbel gene, we identified a 53 bp fragment C53 which could interact with the nuclear proteins extracted from rice endosperm. We also found that fragment Ha-2 in the 5 ’-upstream region of rice waxy gene could compete with C53 for its interaction. Fur-ther experiments demonstrated that rice bZIP protein REB could interact with two ACGT elements (G-box and Hex) in the fragment C53 as well as three ACGT elements (WG1, WG2, and WG3) in the fragment Ha-2. The WG1 element could compete well with Hex element for its interaction with REB. These results suggested that the expression of sbel and waxy gene in rice developing endosperm may be coordinately regulated by REB-like bZIP transcriptional factors.
Rice starch branching enzyme 1 (SBE1) and granule-bound starch synthase (GBSS) catalyzed the bio-synthesis of amylopectin and amylose in rice developing en-dosperm respectively, and the genes encoding these two en-zymes, sbe1 and waxy, are mainly expressed in the en-dosperm. Within the 5 ’-upstream region of rice sbel gene, we identified a 53 bp fragment C53 could could interact with the nuclear proteins extracted from rice endosperm. We also found that fragment Ha-2 in the 5’ -upstream region of rice waxy gene could compete with C53 for its interaction. Fur-ther proteins experiments that rice bZIP protein REB could interact with two ACGT elements (G-box and Hex) in the fragment C53 as well as three ACGT elements (WG1 , WG2, and WG3) in the fragment Ha-2. The WG1 element could compete well with Hex element for its interaction with REB. These results suggest that the expression of sbel and waxy gene in rice developing endosperm may be coordinately regulated by REB- like bZIP transcr iptional factors.