Abstract
Arabidopsis phosphate transporter gene PHT1;1 is known to play an important role on phosphate uptake. Its expression responds to phosphate (Pi) deprivation in root specific manner. To identify the region responsible for Pi starved and root specific expression of PHT1;1, its promoter region was dissected by deletion and chimera analysis in transgenic Arabidopsis plants and hairy root using GUS as a reporter. The results by deletion analysis indicated that Pi- starved expression is controlled by upstream region from -4kb to -1kb. This region contained three WRKY75 binding sequences (TTGACT), which is a modulator of Pi starvation, suggesting that these binding sequences would be recognized by WRKY75. The smallest 0.5kb promoter region containing the first intron also drove GUS gene expression in root specifically without Pi dependent manner. When this intron was deleted, GUS expression was drastically reduced. This suggested that 5'-untranslated region containing the first intron enhances gene expression.
