Promoter elements required for sugar-repression of the RAmy3D gene for alpha-amylase in rice.

There is increasing evidence showing that cereal alpha-amylase gene expression is controlled not only by the classical hormonal regulation, but also by feed-back sugar repression. We demonstrated by in situ hybridization that the sugar repression of rice alpha-amylase gene RAmy3D takes place in scutellar epithelium cells of callus-forming rice embryos. We also used a transient expression system to study the cis-acting elements involved in the sugar repression of the RAmy3D promoter activity. Site-directed mutagenesis of the 50-bp nucleotide sequence from -172 to -123 revealed that consensus sequences of G motif (TACGTA) and TATCCA T/C motif (GATA motif as its antisense sequence) are responsible for sugar repression. The promoter sequences required for sugar repression are reported and discussed.