Generation of transgenic camelina sativa with modified seed fatty acid composition

Abstract

Camelina sativa is an oilseed crop that is currently being developed mainly as an alternative source of bioenergy. To improve its seed fatty acid composition, RNAi was conducted to suppress the expression of fatty acid desaturase 3 (FAD3) and fatty acid elongase 1 (FAE1) in developing seeds for reduction of undesired polyunsaturated fatty acids (PUFA) and very-longchain fatty acids (VLCFAs), which are associated with unsatisfactory fuel properties. At the early flowering stage, camelina wild type (cv. Licalla) was transformed by Agrobacterium tumefaciens mediated floral-dip vacuum-infiltration method. We successfully obtained six transgenic plants. The expression of FAD3 and FAE1 genes were successfully repressed as indicated by quantitative RT-PCR (Q-PCR) analysis. The downregulation of the FAD3 and FAE1 genes by RNAi gene silencing resulted in the reduction of linolenic acid (18:3) and eicosenoic acid (20:1) to about 11% and 4% from about 27% and 15%, respectively in the seeds of untransformed plants. In contrast, linoleic acid (18:2) significantly increased from about 25% to 42%, however oleic acid (18:1) was only slightly increased by about 4-5%. Our results demonstrated that seed-specific suppression of key fatty acid modification genes including FAD3 and FAE1 effectively changed fatty acid composition in camelina oil. An easy genetic transformation protocol should allow for future metabolic engineering for desirable fatty acid profiles and other biotechnology studies in camelina.