Transgenic maize lines expressing a cry1C* gene are resistant to insect pests

The lepidopteran Ostrinia furnacalis is one of the most serious pests of maize production. The Cry1C proteins are group of Bacillus thuringiensis (Bt) proteins that are toxic to the intestine of insects. Overexpression of Cry1C protein has led to increased resistance to lepidopteran pests in several crops. In the present study, the synthetic cry1C* gene that was previously tested in rice was introduced into maize Hi-II genotypes via biolistic gun-mediated transformation. A total of nine independent putative callus were obtained and 87 transgenic plants were positive with cry1C* according to polymerase chain reaction (PCR) analysis. Three highly insect-resistant transgenic plants, ZmKc-2-3, ZmKc-3-2, and ZmKc-3-5, were further confirmed by PCR analysis, field assessment, and genomic southern blotting in the T-3 generations. Insect bioassays were conducted in both the field and the laboratory, and showed that progeny of the three transgenic lines were significantly resistant to lepidopteran maize pests during the whole development and growth period. The stable integration and expression of the cry1C* in the three transgenic plants' progeny were confirmed by reverse transcription-PCR (RT-PCR) and enzyme-linked immuno sorbent assay (ELISA) methods. Hybrids were produced by crossing transgenic line ZmKc-2-3 with the elite inbred line Zheng58. There was small variation among the hybrids and backcross offspring, indicating that these cry1C* transgenic lines can be used to produce insect-resistant hybrids and served as insect-resistant sources for the development of Bt maize.