Auxin Binding Protein 57 (ABP57) is one of the molecular components involved in rice response to abiotic stress. The ABP57 gene encodes an auxin receptor which functions in activating the plasma membrane H+-ATPase. Biochemical properties of ABP57 have been characterized; however, the function of ABP57, particularly on stress and hormone responses is still limited. This study was conducted to understand the regulation of ABP57 expression under abiotic stress. Thus, in silico identification of cis-acting regulatory elements (CAREs) in the promoter region of ABP57 was performed. Several motifs and transcription factor binding site (TFBS) that are involved in abiotic stress such as ABRE, DRE, AP2/EREBP, WRKY and NAC were identified. Next, expression analysis of ABP57 under drought, salt, auxin (IAA) and abscisic acid (ABA) was conducted by reverse transcription-PCR (RT-PCR) to verify the effect of these treatments on ABP57 transcript level. ABP57 was expressed at different levels in the shoot and root under drought conditions, and its expression was increased under IAA and ABA treatments. Moreover, our results showed that ABP57 expression in the root was more responsive to drought, auxin and ABA treatments compared to its transcript in the shoot. This finding suggests that ABP57 is a drought-responsive gene and possibly regulated by IAA and ABA.
Auxin-binding protein from coleoptile membranes of corn (Zea mays L.). I. Purification by immunological methods and characterization.
