JXB Advance Access originally published online on May 28, 2008
Journal of Experimental Botany 2008 59(9):2393-2402; doi:10.1093/jxb/ern112
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© 2008 The Author(s).
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
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RESEARCH PAPER |
Quantitative expression analysis of selected COR genes reveals their differential expression in leaf and crown tissues of wheat (Triticum aestivum L.) during an extended low temperature acclimation regimen
1Department of Plant Sciences, College of Agriculture and Bioresources, University of Saskatchewan, 51 Campus Drive, Saskatoon, Saskatchewan S7N 5A8, Canada
2Crop Research Institute, Drnovska 507, Praha 6, Czech Republic 16106
* To whom correspondence should be addressed. E-mail: ravi.chibbar{at}usask.ca
A number of COR genes (COld-Regulated genes) have been implicated in the acquisition of low temperature (LT) tolerance in wheat (Triticum aestivum L.). This study compared the relative expression patterns of selected COR genes in leaf and crown tissues of wheat near-isogenic lines to increase understanding of the molecular mechanisms underlying LT acclimation. Reciprocal near-isogenic lines were generated such that the dominant Vrn-A1 and recessive vrn-A1 loci were interchanged in a spring cv. Manitou and a winter cv. Norstar. Phenological development, acquisition of LT tolerance, and WCS120 polypeptide accumulation in these genotypes proceeded at rates similar to those previously reported for 6 °C acclimation from 0 to 98 d. However, a differential accumulation of WCS120 polypeptide and expression of the COR genes Wcs120, Wcor410, and Wcor14 was observed in the leaf and crown tissues. COR gene transcript levels peaked at 2 d of the acclimation period in both tissues and differences among genotypes were most evident at this time. COR gene expression was highest for the LT-tolerant and lowest for the tender genotypes. However, expression rates were divergent enough in genotypes with intermediate hardiness that comparisons among tissues and/or times during acclimation often resulted in variable interpretations of the relative expression of the COR genes in the determination of LT tolerance. These observations emphasize the need to pay close attention to experimental conditions, sampling times, and genotype and tissue selection in experiments designed to identify the critical genetic components that interact to determine LT acclimation.
Key words: Dehydrins, low temperature tolerance, near-isogenic lines, real-time PCR, winter cereals
Received 9 January 2008; Revised 29 February 2008 Accepted 18 March 2008