Expression analysis of low temperature-induced genes in wheat
Wheat (Triticum aestivum L.) is a widely adapted, economically important crop exhibiting winter, spring and intermediate growth habits. Winter wheat is seeded in the fall, over-winters, resumes growth in spring and is harvested in early summer. It also requires a period of low temperature (LT) exposure, experienced during the fall, to switch from the vegetative to reproductive phase in spring, a process known as vernalization. Low temperature also allows the wheat plant to cold-acclimate to withstand freezing winter temperatures. There has always been an interest to grow winter wheat because of its yield advantage over spring wheat. However, LT tolerance needs to be improved to prevent winter kill and maximize its yield potential. To achieve this more detailed understanding of molecular mechanisms underlying LT tolerance is required. Thus, objectives of this study were to determine the expression of a LT-induced gene and cDNA-AFLP profile in leaf and crown tissues of LT-exposed wheat plants. Survival of crown tissues after exposure to sub-zero temperatures is an indication of the level of LT tolerance of a cultivar. Thus, pattern and levels of expression of LT-induced genes and identification of LT-induced transcripts in this tissue will add to understanding of LT tolerance. Genotypes used in this study included a winter hardy cultivar, Norstar, a tender spring cultivar, Manitou and two-near-isogenic lines with the Vrn-A1 (spring Norstar) and vrn-A1 (winter Manitou) alleles of Manitou and Norstar, respectively. The dominant Vrn-A1 locus confers spring habit and therefore no requirement for vernalization. Quantitative real-time polymerase chain reaction (QPCR) for the cold-regulated gene, Wcor410, indicated that in leaf tissue the Vrn-A1 locus determined level of expression, being higher in the lines having the recessive vrn-A1 allele compared to the dominant Vrn-A1 allele lines. In the crown tissue, the Norstar genetic background led to the higher level of expression than in the Manitou background. cDNA-AFLP analysis also exhibited variable profiles between the two tissues.
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