The cold-regulated transcriptional activator Cbf3 is linked to the frost-tolerance locus Fr-A2 on wheat chromosome 5A

Abstract

Wheat chromosome 5A plays a key role in cold acclimation and frost tolerance. The major frost tolerance gene Fr-A1 (formerly Fr1) and two loci that regulate the transcription of cold-regulated genes (Cor) have previously been mapped on the long arm of this chromosome. In this study we report the discovery of a new locus for frost tolerance designated Fr-A2. This new locus was mapped on the long arm of chromosome 5A of diploid wheat (T. monococcum), 40 cM from the centromere and 30 cM proximal to the major frost tolerance locus Fr-A1. We found also that frost-tolerant and frost-susceptible T. monococcum parental lines differed in the transcription level of the cold induced gene Cor14b when plants were grown at 15°C. Transcription levels of this gene were measured in each of the recombinant inbred lines and mapped as a QTL that perfectly overlapped the QTL for frost survival at the Fr-A2 locus. This result suggested that frost tolerance in this cross was mediated by differential regulation of the expression of the Cor genes. In a previous study in hexaploid wheat (T. aestivum) we had shown that Cor14b was regulated by two loci located on chromosome 5A, one in the same chromosome region as the T. monococcum Fr-A2 locus and the other one closely linked to Fr-A1. Since CBF transcriptional activators in Arabidopsis regulate Cor genes and are involved in frost tolerance, we decided to localize the cold-regulated CBF-like barley gene Cbf3 on the T. monococcum map. This gene was mapped on the peak of the Fr-A2 QTL for frost tolerance. This result suggests that the observed differential regulation of Cor14b at the Fr-A2 locus is due to allelic variation at the XCbf3 locus, and that this transcriptional activator gene might be a candidate gene for the Fr-A2 frost tolerance locus on wheat chromosome 5A.

A major quantitative trait locus for cold-responsive gene expression is linked to frost-resistance gene <i>Fr-A2</i> in common wheat

“…The chromosomal region of the 5A eQTL corresponded to that of Fr-A m 2 (Fig. 3), which was identified as a frost-tolerance locus in einkorn wheat (Vágújfalvi et al 2003). In addition, the 5A eQTL location coincided with a freezing tolerance QTL on chromosome 5A previously reported using doubled haploid lines of two winter wheat cultivars (Båga et al 2007).…”

“…In einkorn wheat and barley, a CBF gene cluster with more than 10 copies was located on the Fr-A m 2 and Fr-H2 regions, respectively (Francia et al 2007, Miller et al 2006, Skinner et al 2005, Vágújfalvi et al 2003). Einkorn wheat orthologs of TaCBF12 and TaCBF15 are localized at the Fr-A m 2 chromosomal region (Miller et al 2006).…”

“…Fr-1 loci affect the expression of several CBF genes located in the Fr-2 region (Kobayashi et al 2005, Vágújfalvi et al 2005). The map position of the wheat CBF gene cluster and an eQTL of Cor14b correspond to the Fr-A m 2 locus on chromosome 5A of einkorn wheat, Triticum monococcum (Miller et al 2006, Vágújfalvi et al 2003). Similarly, in barley, Hordeum vulgare , multiple CBF copies constitute a gene cluster around a frost tolerance QTL, Fr-H2 , on chromosome 5H (Francia et al 2007, Fricano et al 2009, Skinner et al 2005, 2006).…”

Dissecting the genetic architecture of frost tolerance in Central European winter wheat

“…One prominent frost tolerance locus is Fr-1 (Sutka and Snape, 1989; McIntosh et al , 1998), which maps close to Vrn-A1 and thus has been supposed to represent a pleiotropic effect of Vrn-A1 (Dhillon et al , 2010). An additional locus underlying frost tolerance, Fr-A2 , has been identified on chromosome 5A ~30 cM away from Vrn-A1 (Vágújfalvi et al , 2000, 2003). Homoeologous loci were reported for chromosomes 5B (Toth et al , 2003) and 5D (Snape et al , 1997).…”

Genome-wide association mapping of frost tolerance in barley (Hordeum vulgare L.)

“…The ‘Nure’ (winter) x ‘Tremois’ (spring) barley population [10] is at present the only example of biparental mapping in the Triticeae where both Frost Resistance-H1 , Fr-H1 , and Frost Resistance-H2 , Fr-H2 segregated and were located on a genetic map, approximately 30 cM apart on the long arm of chromosome 5H. A cluster of at least 13 C-repeat Binding Factor ( CBF ) genes [8] co-segregates with the barley ( Fr-H2 ) and the wheat ( Fr- A2) orthologous loci [10,11]. The CBF gene family has been shown to have a critical role in stress response in Arabidopsis and encodes a small family of transcription factors that have been demonstrated to regulate cold acclimation response by controlling the level of COR (cold-regulated) expression, which in turn promotes tolerance to freezing.…”