In silico Study of Promoter Regions in Vacuole-type Sodium/ Hydrogen Exchanger Genes from Canola (Brassica napus L.)

Background and Objective: Vacuole-type NHX proteins are important for plants’ ability to tolerate abiotic stress, especially salt stress. Materials and Methods: To gain information about the mechanisms of molecular regulation of NHX genes under abiotic stresses in canola (Brassica napus L.), in silico method was used to identify cis-acting regulatory elements present in 2.5 kbp upstream regions of identified vacuole-type NHX genes from the canola genome (BnNHXs). Results: A total of 51 cis-acting regulatory elements were identified that showed remarkable differences in frequency and site-specific distribution and they fell into five groups: Light-responsive elements, stress response, hormonal regulation, cellular development and elements with unknown function. The site-specific distribution of stress response and hormonal regulation elements indicated that they were most dense at -1600 to -1800 bp and at -800 bp, that is, far from the transcription start site. The most common motifs were the G-Box and Box 4 cis-elements, followed by the MBS, HSE and ARE motifs from the stress response group and the GARE-motif and ABRE from the hormonal regulation group. The results indicated that regulation of expression of BnNHXs under abiotic stresses involves TC-rich repeats, heat shock elements (HSE), LTR, anaerobic responsive element (ARE), Box-W1, MBS, CCAAT-box, ABA-responsive elements (ABRE), CGTCA-motif, TGACG-motif and ERE. Conclusion: This study provided information on the mechanisms by which BnNHX genes are regulated under abiotic stresses in canola.