Regulation of desaturase gene expression, changes in membrane lipid composition and freezing tolerance in potato plants

Transplastomic tobacco plants expressing a fatty acid desaturase gene exhibit altered fatty acid profiles and improved cold tolerance

“…The same plant-derived ACP D 9 desaturase gene used in the present study has been recently overexpressed in nuclear transgenic Solanum tuberosum, exhibiting a slight increase in 18:3 and a concomitant reduction in 18:0 content. No changes were observed in hexadecanoic fatty acids, whereas 18:1D 11 vaccenic acid was detected in both the PC (phosphatidylcholine) and PE (phosphatidylethanolamine) microsomal fractions (De Palma et al 2008). Similarly, Arabidopsis plants overexpressing either the SSI2 or the DES1 genes, both encoding a stearoyl-ACP D 9 desaturase, were morphologically indistinguishable from wild-type plants, showing comparable 18:1 levels as well as normal salicilic acid/jasmonic acid responsiveness (Kachroo et al 2007).…”

“…Two des transcripts were observed in the leaves of both WC1 and WC10 transformants, an abundant transgenic specific monocistronic mRNA and a less abundant (20-35% of the former) larger transcript that likely resulted from read-through transcription due to poor termination that is inherent in many plastidial 3 0 regulatory sequences (Maliga 2002). On the other hand, a relatively weak expression of the potato desaturase protein was shown by pWC1-derived plants, being its production level about four-fold less than in the nuclear transgenic potato plant transformed with the same transgene (De Palma et al 2008) used as positive control. In previous experiments, transplastomic plants, containing either one of the two D 9 desaturase transgenes as dicistronic constructs with the selectable aadA marker gene, produced the expected transcripts at comparable levels of the plants produced in this study, but no protein could be detected (Craig et al 2004), suggesting that limited accumulation of the D 9 desaturase enzyme does not depend only on differences in mRNA abundance.…”

“…Protein extractions from Scdes transformed and control plants, grown either in vitro as shoot cultures or in soil, were carried out according to De Palma et al (2008). Eighty microgram of total proteins were separated by SDS-PAGE on 12.5% acrylamide gel, transferred to nitrocellulose membrane and incubated with a polyclonal antibody raised against a synthetic peptide derived from the predicted S. commersonii desaturase amino acidic sequence (De Palma et al, 2008).…”

“…Eighty microgram of total proteins were separated by SDS-PAGE on 12.5% acrylamide gel, transferred to nitrocellulose membrane and incubated with a polyclonal antibody raised against a synthetic peptide derived from the predicted S. commersonii desaturase amino acidic sequence (De Palma et al, 2008). Protein signals after Western Blotting in transplastomic plants and nuclear transgenic positive control were compared by the QuantityOne software (Biorad).…”

“…In order to verify the possibility of manipulating the unsaturation level of fatty acids via plastid transformation, we introduced two D 9 desaturase genes, derived either from the wild potato species Solanum commersonii (De Palma et al 2008) or the cyanobacterium Anacystis nidulans (Ishizaki-Nishizawa et al 1996), into the tobacco plastid genome. The former gene controls the conversion of ACP-stearic acid (18:0) into ) in the plastid (Somerville et al 2000), while the latter is responsible for the production of oleic and palmitoleic (16 : 1 D 9 ) acids from lipid-linked stearic and palmitic (16:0) acids, respectively, in the cyanobacterial cell (Ishizaki-Nishizawa et al 1996).…”