Chinese tallow (Sapium sebiferum) is an important oil tree and herbal
medicine in China. Stearoyl-acyl carrier protein desaturase (SAD) is an
enzyme that is involved in the transformation of saturated fatty acids into
unsaturated fatty acids in oil, which influences the freezing tolerance of
plants. A research team led by Dan Peng of the College of Bioscience and
Biotechnology of Central South University of Forestry and Technology in
China aimed to test if freezing tolerance can be regulated by controlling
the expression of SsSAD.
The team found that SsSAD expression in Chinese tallow increased under
freezing stress. To confirm this, researchers overexpressed SsSAD in oilseed
rape (Brassica napus). Oilseed rape plants overexpressing the SsSAD gene
exhibited significantly higher linoleic (18:2) and linolenic acid (18:3)
content as well as enhanced freezing tolerance.
These results suggest that SsSAD overexpression in oilseed rape can increase
the content of polyunsaturated fatty acids, which are pivotal in improving
freezing tolerance. SsSAD overexpression could therefore be useful in the
production of freeze-tolerant varieties of oilseed rape.