The FAD7 gene, a gene for a chloroplast ω-3 fatty acid desaturase, is responsible for the trienoic fatty acid (TA) formation in leaf tissues. The TA content of the leaf tissue of the 25°C-grown transgenic tobacco (Nicotiana tabacum cv SR1) plants, in which the FAD7gene from Arabidopsis thaliana was overexpressed, increased uniformly by about 10%. Fatty acid unsaturation in all major leaf polar lipid species increased in the 25°C-grown FAD7 transformants but was approximately the same between the control plants and the FAD7 transformants when grown at 15°C. Therefore, the overexpression of the exogenous FAD7 gene leads to the same consequence in the tobacco plants as the low-temperature-induced TA production that may be catalyzed by an endogenous, temperature-regulated chloroplast ω-3 fatty acid desaturase. In the 25°C-grown control plants, the chilling treatment caused symptoms of leaf chlorosis and suppression of leaf growth. The 25°C-grown FAD7 transgenic plants conferred alleviation of these chilling-induced symptoms. A reduction of the chilling injury similar to that of the FAD7 transformants was also observed in the 15°C-preincubated control plants. These results indicate that the increased TA production during chilling acclimation is one of the prerequisites for the normal leaf development at low, nonfreezing temperatures.
All Science Journal Classification (ASJC) codes
- Plant Science