Molecular cloning and expression analysis of PDR1-like gene in ginseng subjected to salt and cold stresses or hormonal treatment.

Abstract The plant pleiotropic drug resistance (PDR) family of ATP-binding cassette (ABC) transporters is potentially involved in diverse biological processes. Currently, little is known about their actual physiological functions. A Panax ginseng PDR transporter gene ( PgPDR1 ) was cloned and the cDNA has an open reading frame of 4344 bp. The deduced amino acid sequence contained the characteristic domains of PDR transporters: Walker A, Walker B, and ABC signature. Genomic DNA hybridization analysis indicated that one copy of PgPDR1 gene was present in P. ginseng . Subcellular localization showed that PgPDR1-GFP fusion protein was specifically localized in the cell membrane. Promoter region analysis revealed the presence of cis-acting elements, some of which are putatively involved in response to hormone, light and stress. To understand the functional roles of PgPDR1 , we investigated the expression patterns of PgPDR1 in different tissues and under various conditions. Quantitative real-time PCR (qRT-PCR) and Western blotting analysis showed that PgPDR1 was expressed at a high level in the roots and leaves compared to seeds and stems. The expression of PgPDR1 was up-regulated by salicylic acid (SA) or chilling, down-regulated by ABA, and regulated differently at transcript and protein levels by MeJA. These results suggest that PgPDR1 might be involved in responding to environmental stresses and hormones.