Identification, cloning and characterization of some antimicrobial peptide defensin from oat plant Avena sativa

The emergence antibiotic resistant among pathogenic bacteria has become a serious threat to global public health in recent decades. With regards to the increasing prevalence of resistance to conventional antibiotics, many studies have focused on the development of antimicrobial peptides as an alternative antibacterial therapy. Defensins, are group of cysteine-rich antimicrobial peptides that are present in animals and plants. They are as components of the host defense system which acts against pathogens and pests. The purpose of this study was to identify, clone and characterize of some defensins genes from oat plant. For this purpose, the complete gene family of wheat was retrieved from GenBank and aligned against oat plant transcriptome. The resulted sequences were assembled and obtained contigs and singletons were aligned against nr database using BLASTn tools. The results were evaluated for the presence of complete ORF and sequences with complete ORF were used for primer designing. Then, the total RNA was extracted from oat pooled tissues and cDNA were synthesized. The fragments were amplified, cloned in pTZ57R/T vector and sequenced. The results of bioinformatics analysis, confirmed the presence of the nine genes encoding defensin in oat plant transcriptome. Five of these genes were cloned and sequenced. These genes contained the complete ORFs between 234-246 bp that produced peptides with length 77-81 amino acids. In addition, identified defensins comprised Knot1 functional domain from the gamma-thionin family. Identification and characterization of genes is the first step in the genetic engineering and production of organisms with favorable traits. In this study for the first time, the complete coding sequence of five defensin genes were isolated and characterized from the oat plant.