Evidence for the up-regulation of stearoyl-ACP (Δ9) desaturase gene expression during cold acclimation

Abstract

Our previous studies demonstrated that an increase in 18:2 (linoleate) in the purified plasma membrane fraction during cold acclimation is associated with genetic variations in cold acclimation capacity. This increase was found only in genotypes that are able to cold acclimate and was reversible on deacclimation suggesting a link between the accumulation of 18:2 and acquisition of freezing tolerance. The present study was aimed at understanding the association between the induction of stearoyl-ACP (acyl carrier protein) (Δ9) desaturase and the ability to cold acclimate. Our approach was to study the induction of Δ9 desaturase at the transcript level using potato Δ9 desaturase gene-specific primers and reverse transcription polymerase chain reaction (RT-PCR). For this purpose, total RNA fromSolanum tuberosum (cold sensitive, unable to acclimate) andSolanum commersonii (cold tolerant, able to cold acclimate) was extracted before and after cold acclimation. RT-PCR produced a single band and sequence analysis confirmed that the amplified band was Δ9 desaturase. While the cold acclimating species,Solanum commersonii, exhibited an increase in Δ9 desaturase transcript levels after cold acclimation, the cold non-acclimating species,Solanum tuberosum, exhibited no change. Our results show that the increase in Δ9 desaturase gene transcripts during cold acclimation is associated with the cold acclimation response in potato.