Function Identification of the Nucleotides in Key -Element of () Promoter.

As a core regulatory gene of the anther development, () was expressed in tapetum preferentially. Previous study had confirmed that a "CTCC" sequence within promoter was indispensable for correct expression. However, precise analysis on the function of each nucleotide of this sequence still lacks. Here we employed site mutation assay to identify the function roles of the nucleotides. As a result, the "T" and final "C" of "CTCC" were found essential for the temporal and spatial specificity of expression, whereas the other two "C" nucleotides exhibited substitutable somewhat. The substitutes of two flanking nucleotides of "CTCC," however, hardly affected the normal promoter function, suggesting that the "CTCC" sequence as a whole did meet the standard of a canonical -element by definition. In addition, it was found that as short as 497 bp promoter was sufficient for tissue-specific expression, while longer 505 bp promoter sequence was sufficient for species-specific expression.