title: Chloroplast-targeted expression of synthetic cry1Ac in transgenic rice as an alternative strategy for increased pest protection.
abstract: To increase insect resistance in transgenic rice plants, a synthetic truncated cry1Ac gene was linked to the rice rbcS promoter and its transit peptide sequence (tp) for chloroplast-targeted expression. Several transgenic lines were generated by the Agrobacterium-mediated transformation method and the expression levels of the transgene were compared with untargeted expression. Use of the rbcS-tp sequence increased the cry1Ac transcript and protein levels by 25- and 100-fold, respectively, with the accumulated protein in chloroplasts comprising up to 2% of the total soluble proteins. The high level of cry1Ac expression resulted in high levels of plant resistance to three common rice pests, rice leaf folder, rice green caterpillar, and rice skipper, as evidenced by insect feeding assays. Transgenic plants were also evaluated for resistance to natural infestations by rice leaf folder under field conditions. Throughout the entire period of plant growth, the transgenic plants showed no symptoms of damage, whereas nontransgenic control plants were severely damaged by rice leaf folders. Our results demonstrate that the targeting of cry1Ac protein to the chloroplast using the rbcS:tp system confers a high level of plant protection to insects, thus providing an alternative strategy for crop insect management.
authors.affiliation: School of Biotechnology and Environmental Engineering, Myongji University, Yongin, 449-728, South Korea.
authors.forename: Eun Hye
authors.initials: EH
authors.lastname: Kim
authors.forename: Seok Cheol
authors.initials: SC
authors.lastname: Suh
authors.forename: Beom Seok
authors.initials: BS
authors.lastname: Park
authors.forename: Kong Sik
authors.initials: KS
authors.lastname: Shin
authors.forename: Soon Jong
authors.initials: SJ
authors.lastname: Kweon
authors.forename: Eun Jung
authors.initials: EJ
authors.lastname: Han
authors.forename: Su-Hyun
authors.initials: SH
authors.lastname: Park
authors.forename: Youn Shic
authors.initials: YS
authors.lastname: Kim
authors.forename: Ju-Kon
authors.initials: JK
authors.lastname: Kim
mesh_terms: D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D015152:Blotting, Northern; D015153:Blotting, Western; D002736:Chloroplasts / Q000235:genetics / Q000378:metabolism*; D004731:Endotoxins / Q000235:genetics / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D006460:Hemolysin Proteins / Q000235:genetics / Q000502:physiology*; D007313:Insecta / Q000502:physiology*; D012275:Oryza / Q000235:genetics / Q000378:metabolism* / Q000469:parasitology*; D010572:Pest Control, Biological; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism* / Q000469:parasitology*
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis