5' distal and proximal cis-acting regulator elements are required for developmental control of a rice seed storage protein glutelin gene

Abstract

Using a homologous transgenic rice system it is demonstrated that 5' distal and proximal cis-acting transcriptional regulatory elements are required for developmental control of a rice seed storage protein glutelin gene. Analyses of gene expression of nine progressively truncated 5' promoter sequences in developing endosperm indicated the existence of at least one major positive element located from the -5.1 to -1.8 kb region. The functional importance of proximal elements in the context of 1.8 kb promoter was demonstrated by single substitution mutations in the TATA box (-28/-23), AACA motif (-73/-61), and protein-binding boxes I (-103/-86), II (-124/-110), III (-175/-158) and IV (-200/-217). A simultaneous mutation of five protein-binding sites (-410/-86) essentially eliminated the activity of the 1.8 kb promoter. Although temporal control of the Gt1 gene during endosperm development was retained in plants of constructs from -5.1 kb to -155 bp, spatial control of the glutelin gene was altered when the 5.1 kb promoter was deleted to -507 bp or -154 bp as the reporter gene activities of these constructs were detected in phloem of leaves, and in stems, sheaths and roots of plants.