Transgenic Rice Expressing a Fusion Protein of Cry1Ab and Cry9Aa Confers Resistance to a Broad Spectrum of Lepidopteran Pests

Abstract

ABSTRACTThe truncated active Bacillus thuringiensis endotoxin genes, cry1Ab and cry9Aa, were fused to create a fusion gene, cry1Ab–cry9Aa, encoding a protein of about 146 kDa with Cry1Ab at the N terminus and Cry9Aa at the C terminus. The fusion protein expressed in Escherichia coli is highly active against some major lepidopteran pests—oriental armyworm [Mythimna separata (Walker)], Asian corn borer [Ostrinia furnacalis (Guenée)], cotton bollworm [Helicoverpa armigera (Hübner)], and tobacco cutworm [Spodoptera litura (Fabricius)]. This fusion gene under the control of the corn (Zea mays L.) polyubiquitin‐1 promoter was transformed into rice (Oryza sativa L.) via Agribacterium‐mediated transformation. Western blot analysis suggested that the transgenic lines, C19‐2 and C19‐25, were two high expressers among the 35 transgenic lines obtained. Southern blot analysis revealed that the line C19‐2 contains a single copy of the T‐DNA, while the C19‐25 has three copies. Insecticidal activity assays demonstrated that most of the transgenic rice lines expressing this fusion protein are highly resistant to rice stem borer [Chilo suppressalis (Walker)] and rice leaf folder [Cnaphalocrocis medinalis (Guenée)]. This study suggested that this fusion gene could be useful for engineering transgenic crops for the control of lepidopteran pests.