Reduction of Trienoic Fatty Acid Content by Expression of a Double-Stranded RNA of a Plastid ω-3 fatty Acid Desaturase Gene in Transgenic Tobacco

Plastid ω-3 fatty acid desaturase catalyzes the conversion of dienoic fatty acids (16:2 and 18:2) to trienoic fatty acids (16:3 and α-18:3) in glycerolipids which are the main constituents of chloroplast membranes. We produced transgenic tobacco plants that express the transcript of a double-stranded RNA (dsRNA) of tobacco plastid ω-3 fatty acid desaturase gene, NtFAD7. In these transgenic plants, 16:3 and α-18:3 content in leaves decreased to less than 2.7% and 7.5–10.4%, respectively, when compared with the control plant. The steady-state NtFAD7 mRNA was not detected in the transgenic plants. These results indicate that down-regulation of the transcript level in the NtFAD7 by introduction of NtFAD7 dsRNA constructs is useful to decrease the trienoic fatty acid contents of the vegetative tissues in higher plants.