Author
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Skinner, Daniel |
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Submitted to: Functional and Integrative Genomics
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 5/12/2009 Publication Date: 10/12/2009 Citation: Skinner, D.Z. 2009. Post-acclimation transcriptome adjustment is a major factor in freezing tolerance of winter wheat. Funct Integr Genomics. 9:513–523. DOI 10.1007/s10142-009-0126-y Interpretive Summary: Winter wheat is planted in the fall and must endure being frozen for many weeks in the winter. Many studies have shown that the expression levels of numerous genes change when the plants are exposed to low, above freezing temperatures, conditions that induce cold acclimation. However, changes in expression levels of genes in fully cold-acclimated plants as they are frozen to potentially damaging levels have not been studied. In this study microarray analysis was used to monitor gene expression in cold-acclimated plants of winter wheat cultivars Norstar and Tiber as they were frozen to -10C, and then were either maintained at -10C or the temperature was lowered to -12C. Expression levels of a total of 423 genes were significantly altered in these treatments; genes that increased expression outnumbered genes that decreased expression by about a 9: 1 ratio. Most genes responded similarly in plants of the very freezing tolerant cultivar Norstar and in plants of the moderately freezing tolerant cultivar Tiber. However, some genes responded in opposite fashion in the two cultivars. These results suggested that cold-acclimated wheat crowns actively adapt as the temperature decreases to potentially damaging levels, and that genetic variation for this ability exists among cultivars. This information provides access to previously unknown genetic variation for freezing tolerance in winter wheat. Technical Abstract: The ability of cold-acclimated wheat plants to survive freezing to several degrees below 0C varies among wheat genotypes. While the transcriptional regulation of the cold acclimation process above 0C has been studied extensively, very little is known of the changes in gene expression that may occur as the temperature decreases to potentially damaging levels well below 0C. Using microarray and quantitative real - time PCR analysis, this study evaluated transcriptomic variation of cold-acclimated winter wheat plants as the temperature was lowered to -10C, and then was either maintained at -10C or was lowered further to -12C. Expression levels of a total of 423 genes were significantly altered in these treatments; genes upregulated outnumbered those downregulated by about a 9: 1 ratio. Many of the most strongly responsive genes apparently were involved in transcription regulation or signal transduction. Five genes were significantly upregulated in plants frozen to -12C, compared to plants frozen to -10C and held at -10C for the same amount of time required for the temperature to reach -12C. Most genes responded similarly in plants of the very freezing tolerant cultivar Norstar and in plants of the moderately freezing tolerant cultivar Tiber. However, some genes responded in opposite fashion in the two cultivars. These results suggested that cold-acclimated wheat crowns actively adapt as the temperature declines below 0°C to potentially damaging levels, and that genetic variation for this ability exists among cultivars. This information provides access to previously unknown genetic variation for freezing tolerance in winter wheat. |
