Transgenic tobacco expressing a novel Bt gene, cry1AcF, show resistance against fall armyworm (Spodoptera frugiperda)

Spodoptera frugiperda is a notorious insect-pest that causes massive yield losses to several agriculturally important food crops every year. S. frugiperda decimates food crops like tomato, potato, cotton, sugarcane, brinjal globally. Various pest resistance genes have been deployed to improve crop resistance towards insect pests, mainly through the transgenic expression of Cry toxins. In this study, we showed that a chimeric Bt gene cry1AcF developed by swapping the domains of cry1Ac and cry1F genes, was effective against S. frugiperda . The T-DNA region harbouring cry1AcF gene under the transcriptional control of CaMV35S promoter was introduced into tobacco ( Nicotiana tabacum L. cv. Petit Havana) using Agrobacterium- mediated plant transformation. The transgenic tobacco plants were initially screened on kanamycin and characterized by PCR and Southern hybridization to confirm the transgene integration. Cry1AcF expression was detected with strip test and western blot experiments. Insect bioassay was performed with detached leaves to evaluate the extent of leaf damage and larval mortality in order to select transgenic events with superior performance. Further, insect bioassay conducted using selected transgenic lines, resulted up to 82% larval mortality, indicating high efficacy against S. frugiperda . Therefore, in this study, the transgenic tobacco lines expressing cry1AcF gene showed resistance against S. frugiperda insect. Further, the cry1AcF gene could be effectively utilized to combat resistance against S. frugiperda in other susceptible crops.