Identification of DNA Photolyase Gene of a Drought Tolerance Branching Line of Kenaf (<i>Hibiscus cannabinus</i> L.)

Abstract

DNA photolyase is a photoreactivation enzyme which has a role in the mechanism of DNA repair. The existence of DNA photolyase gene could affect the success of mutation process. SM026H is a drought tolerance branching line of kenaf identified by Research Institute for Tobacco and Fibre Crops, Karangploso, Malang, Indonesia which has a potential as a source for mutation breeding. In this research, cloning and sequencing of the DNA photolyase gene of line SM026H were conducted. The DNA of SM026H leaves was isolated using DNeasy Kit, then was amplified by Polymerase Chain Reaction (PCR) using AC1 as a forward primer, paired with AC3R or AC4R as reverse primers and checked using electrophoresis on a 0.7% agarose gel. The AC1-AC3R primer pair produced a DNA fragment with a size of 750 bp, whereas the AC1-AC4R primer pair produced a DNA fragment of 1000 bp in size. Cloning of the AC1-AC3R and AC1-AC4R fragments was done prior to sequencing. Preparation for cloning was done by running and extracting the PCR products from a 0.7% Low Melting Agarose (LMA), and then ligating them to a pCR21 plasmid using an electroporation method. Two sub-fragments of each AC1-AC3R and AC1-AC4R fragments were identified. They were 600 bp and 500 bp, resulting from the AC1-AC3R fragment, and 1300 bp and 500 bp, resulting from the AC1-AC4R fragment. The sequencing result of those sub-fragments was analyzed using a Basic Local Alignment Search Tool (BLAST) program. It was shown that the sequences have a degree of homology to DNA photolyase sequence of Arabidopsis thaliana A. thaliana , Cucumis sativus , Spinacia oleracea , Stellaria longipes and Oryza sativa . These suggested that the kenaf line SM0026H possesses the DNA photolyase gene. However, further study needs to be done to ascertain that the gene was not the cryptochrome.