Although progression of genome-based techniques has been revamping several areas of genetic engineering, reliable and efficient procedures are expected to unveil structural and functional information of genes. Many methods such as chromosome walking and molecular cloning that are used to recognize unknown flanking sequences are effortful and time-consuming. Here, we report the identification of an unknown upstream regulatory region of actin gene from Plectranthus amboinicus and eight other medicinal plants using thermal asymmetric interlaced PCR (TAIL PCR). As actin is a ubiquitous protein that plays a significant role in developmental stages of plants, we set out to isolate the 5′ flanking region of the actin gene. Three heterologous gene-specific primers were designed based on plant Arabidopsis actin conserved sites, and arbitrary degenerate primers were used for the isolation of putative promoter sequence. Successful amplification was observed in most of the plants tested, thus proving that TAIL PCR is an efficient, effective, and economic procedure for the isolation of promoter sequences from various plants.

Graphic abstract