|Del rio, A|
Submitted to: American Journal of Potato Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/15/2004
Publication Date: 3/15/2004
Citation: Vega, S.E., Del Rio, A.H., Bamberg, J.B., Palta, J.P. 2004. Evidence for the up-regulation of stearoyl-acp delta 9 desaturase gene expression during cold acclimation. American Journal of Potato Research. 81:125-135. Interpretive Summary: Potato is the world's most important vegetable crop, and one of our best hopes for feeding an increasingly hungry world. One limitation to expanded potato production is a lack of frost hardiness in all current commercial varieties. However, some wild relatives of potato can withstand very hard frosts. They are able to survive sudden frosts, but, in some cases are also able to increase their tolerance to cold if "acclimated" by exposure to cool temperatures for a few days. When the biochemical basis of this acclimation was investigated, only acclimating plants that were treated with cool temperatures turned on their genes for production of a certain enzyme called delta 9 desaturase. This is strong evidence that this particular enzyme could have a physiological association with cold acclimation. Such information is a useful clue about the mechanism of cold acclimation in potato and will guide efficient breeding of this valuable trait into future varieties.
Technical 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) delta 9 desaturase and the ability to cold acclimate. Our approach was to study the induction of delta 9 desaturase at the transcript level using potato delta 9 desaturase gene specific primers and reverse transcription polymerase chain reaction (RT-PCR). For this purpose, total RNA from Solanum tuberosum (cold sensitive, unable to acclimate) and Solanum 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 delta 9 desaturase. While the cold acclimating species, Solanum commersonii, exhibited an increase in delta 9 desaturase transcript levels after cold acclimation, the cold non-acclimating species, Solanum tuberosum, exhibited no change. Our results show that the increase in delta 9 desaturase gene transcripts during cold acclimation is associated with the cold acclimation response in potato.