Deep Sequencing of Cold-Acclimated Wheat Crown Transcriptome

Low temperature is a major environmental stress that affects plant growth and development thus, determines their geographical distribution and yield. Plants in temperate regions have evolved adaptive mechanisms to tolerate low temperatures, one of which is the ability to cold-acclimate. Cold acclimation is a process by which a cumulative increase in the ability to tolerate low temperature develops when exposed in low-non freezing temperature. Cold acclimation response can occur within days of exposure to cold.  The Triticeae tribe of the grass family which includes wheat, rye and barley, are some of the most cold-hardy winter annual plants.  Phenotypic studies have shown that cold acclimation in wheat and its relatives start at different temperatures and that rapid changes in freezing tolerance occur during the early stages of cold acclimation.  To gain insight into the underlying mechanisms that regulate the induction of cold-acclimation and to identify the critical genes involved in the early stages of this process we compared the expression of genes in cold treated crowns of two winter-habit cultivars (winter Norstar and winter Manitou) which vary in their tolerance to cold. We sequenced 6 RNA-seq libraries for each cultivar to identify the genes expressed in the crowns of juvenile plants cold-acclimated at 6^o C and 18^oC for 12-hrs, 60-hrs and 380-hrs. These conditions allowed us to target and bracket the threshold induction temperature previously reported for each genotype.  The 2.6 billion reads generated enabled the establishment of a reference transcriptome for cold acclimated wheat crown.