Functional Characterization of a Chrysanthemum dichrum Stress-Related Promoter

A 1,474-bp stress-inducible CdDREBa promoter was identified from Chrysanthemum dichrum, revealing several candidate stress-related cis-acting elements (MYC-box, MYB site, GT-1, and W-box) within it. In Arabidopsis leaf tissues transformed with a CdDREBa promoter-beta-glucuronidase (GUS) gene fusion, serially 5'-deleted CdDREBa promoters were differentially activated by cold and salinity. Histochemical and quantitative assays of GUS expression allowed us to localize a critical part of the promoter located between upstream 430 and 351 nt. This 80-bp fragment enhanced GUS expression under salinity stress when fused to -90/+8 CaMV 35S minimal promoter. Further promoter internal-deletion assays indicated that a low temperature-responsive element was located between positions -430 and -390, and a salinity inducible one between -385 and -351. Our results showed that there was a novel stress-related critical region except for the known cis-acting element (MYC-box, GT-1) in CdDREBa promoter.