MSI-99, a magainin analogue, imparts enhanced disease resistance in transgenic tobacco and banana

Magainin is one of the earliest reported antimicrobial peptides isolated from skin secretions of the African clawed frog Xenopus laevis. A synthetic substitution analogue of magainin, MSI-99, is employed in this study to impart disease resistance in transgenic tobacco (Nicotiana tabacum L.) and banana [(Musa spp. cv. Rasthali (AAB)]. This peptide inhibited the growth and spore germination of Fusarium oxysporum f.sp. cubense at 16 mug/ml. MSI-99 has been subcloned into plant expression vectors pMSI164 and pMSI168, targeting the peptide into the cytoplasm and extracellular spaces, respectively. Tobacco plants transformed with pMSI168 showed enhanced resistance against Sclerotinia sclerotiorum, Alternaria alternata and Botrytis cinerea. Transgenic banana pants were obtained for both pMS1164 and pMSI168 transformations and showed resistance to F. oxysporum f.sp. cubense and Mycosphaerella musicola. The transgenic nature of the transformants and expression of this peptide was confirmed through polymerase chain reaction (PCR) and reverse transcription (RT)-PCR. The results suggest that MSI-99 can be useful in imparting enhanced disease resistance in transgenic plants.