Abstract

                                Fusarium wilt caused by Fusarium oxysporum f. sp. cubense (Foc) is a devastating disease of banana. Race 1 of Fusarium wilt is a serious threat to Musa spp. cv. Rasthali (AAB, Silk subgroup), which is a choice variety traditionally grown in most of the South East Asian countries. The investigation was an attempt to study whether RNAi-mediated expression of small interfering RNAs (siRNAs) targeted against ftf1 (fusarium transcription factor1) gene in transgenic banana could impart resistance against Foc race 1. Partial sequences comprising sense and antisense sequences of ftf1 gene were assembled as siRNA construct in a binary vector background and transformed into embryogenic cell suspensions of banana cv. Rasthali by Agrobacterium mediated genetic transformation. Presence of RNAi construct in transgenic banana plants were confirmed by polymerase chain reaction assay. Forty- six transformed lines derived from RNAi-FTF1 were found to be free of external symptoms of Foc after 3 months of challenge inoculation. Seventeen transgenic lines continued to resist the Foc race 1 even after six months of post inoculation. The present study confirmed that the host induced RNAi-mediated gene silencing of a fungal gene could confer resistance against Foc in banana.

Key words : Banana Fusarium wilt; Fusarium oxysporum f. sp. cubense; RNA interference; fusarium transcription factor 1