Development of transgenic Sorghum bicolor (L.) Moench resistant to the Chilo partellus (Swinhoe) through Agrobacterium-mediated transformation

Abstract

An Agrobacterium mediated gene transformation was developed in Sorghum for insect resistance using shoot apices. Sorghum spotted stem borer (Chilo partellus Swinhoe) is an important insect pest of sorghum which causes severe damage in many parts of the world. Sorghum plants were transformed with fully modified synthetic Cry1C coding sequences along with hpt and gus genes. The calli developed from shoot apices of APK 1 cultivar were inoculated with Agrobacterium strain. Embryogenic calli from the shoot apices were selected on the medium containing hygromycin B. A total of 76 hygromycin resistant plants were regenerated. PCR was performed to confirm the presence of the Cry1C gene. All the three putative transformants were found to be positive for the amplification of 1.9 kb Cry1C gene. A similar band was also observed in the positive plasmid control. Southern blot analysis of transformants confirmed integration of 2.9 kb Cry1C coding sequences into the sorghum genome. S1 progeny plants disclosed a monogenic pattern (3:1) of transgene segregation. The efficiency of transformation in our study was between 1.2%-3.9%. These transgenic lines were highly resistant to the spotted stem borer Chilo partellus as revealed by insect bioassay with 100% insect mortality rate.