Transcriptional regulation of salinity stress: role and spatio-temporal expressions of ion-transporter gene promoters

Ion transporters play an important role in ion homeostasis and control ion flow from its intrusion to exclusion in the entire plant system. Abiotic stress tolerance in plants depends immensely on the activity of these transporters. The transporter proteins are transcriptionally regulated by cis-elements present in their upstream region for specific activity. The presence of different cis-elements facilitates cross-talk between different signal transduction pathways. Depending on the cis-elements, a specific stress signalling pathway is activated, eliciting a physiological change towards maintaining ion homeostasis to alleviate stress. Beta-glucuronidase localization studies using various promoter regions indicated their expression specificity in organs/tissues. This review gives an overview about promoter activity of different transporters and its involvement under salinity stress.