Abstract
Many organisms produce small proteins which exhibit antimicrobial activities. In recent decades, the biological role of antimicrobial peptides (AMP) has been recognized as the main factor in the defense mechanisms against a broad range of pathogenic microbes. The increased worldwide incidence of microbial resistance to antibiotics makes AMPs promising alternative for the control of microbial disease. Exploring the potential of AMPs in transgenic crops could lead to the development of new and improved cultivars which are resistant to various economically important diseases. In the present study, two fusion lytic peptide gene constructs coding for antimicrobial peptides were expressed in Nicotiana benthamiana tobacco plants and tested against three fungal pathogens, Sclerotinia sclerotiorum, Rhizoctonia solani, and Pythium sp. Detached-leaf bioassay was employed for the transgenic plants carrying the fusion lytic peptide constructs (ORF13 and RSA1), transgenic vector only control plants (1234), and wild-type control plants (WT) against the three fungal pathogens. Symptom area of each leaf was measured with high accuracy and data were recorded and processed by statistical analyses. The results showed that transgenic plant lines ORF13 and RSL1 have substantial resistance to Sclerotinia sclerotiorum infection, producing significantly smaller lesion areas compared to vector only plant line 1234 and wild type plants. These transgenic lines also provided resistance against Rhizoctonia solani, however, these lines were not effective against the other fungal pathogen Pythium sp.