Submitted to: PLoS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/23/2015
Publication Date: 7/14/2015
Citation: Skinner, D.Z. 2015. Genes upregulated in winter wheat (Triticum aestivum L) during mild freezing and subsequent thawing suggest sequential activation of multiple response mechanisms. PLoS One. 10(7):e0133166.
Interpretive Summary: The ability for wheat plants to survive the winter months while frozen has been difficult to improve and many fields are lost each year to winter kill. It recently was discovered that exposing wheat plants to mild freezing, followed by thawing at low, above-freezing temperatures, greatly improved the plants’ ability to survive subsequent freezing to potentially damaging temperatures. This research investigated the genetic basis of that improved freezing tolerance. About 2,000 genes and many physiological processes were found to be involved. Although complex, this result provides new guidance on how to measure individual wheat lines for their ability to use the freeze-thaw enhanced freezing tolerance, potentially providing a means to improve the ability of wheat to survive over the winter in the field.
Technical Abstract: Exposing fully cold-acclimated wheat plants to a freeze-thaw cycle of -3°C for 24h followed by +3°C for 24 or 48h resulted in dramatically improved freezing tolerance. To assess the transcriptomic changes that occur during the -3°C freeze, and the subsequent +3°C thaw, microarray analysis was applied to RNA from crown tissue from plants that had been cold-acclimated at +3°C for 5 wks, incubated at -3°C for 24 hours, then allowed to thaw at +3°C for 24h or 48h. Nearly 2,000 genes were significantly upregulated over the 72 h course of freezing and thawing, but more than 70% of these genes were upregulated during only one of the time periods examined, suggesting a series of processes led to enhanced freezing tolerance. This progression of processes appeared to include extensive cell signaling, activation of stress response mechanisms and the phenylpropanoid biosynthetic pathway, extensive modification of secondary metabolites, and physical restructuring of cell membranes. By identifying plant lines that are especially able to activate these multiple mechanisms it may be possible to develop lines with enhanced winterhardiness.