Two loci on wheat chromosome 5A regulate the differential cold-dependent expression of the cor14b gene in frost-tolerant and frost-sensitive genotypes

Abstract

Although cold acclimation in cereals involves the expression of many cold-regulated genes, genetic studies have shown that only very few chromosomal regions carry loci that play an important role in frost tolerance. To investigate the genetic relationship between frost tolerance and the expression of cold-regulated genes, the expression and regulation of the wheat homolog of the barley cold-regulated gene cor14b was studied at various temperatures in frost-sensitive and frost-tolerant wheat genotypes. At 18/15°C (day/night temperatures) frost-tolerant plants accumulated cor14b mRNAs and expressed COR14b proteins, whereas the sensitive plants did not. This result indicates that the threshold temperature for induction of the wheat cor14b homolog is higher in frost-resistant plants, and allowed us to use this polymorphism in a mapping approach. Studies made with chromosome substitution lines showed that the polymorphism for the threshold induction temperature of the wheat cor14b homolog is controlled by a locus(i) located on chromosome 5A of wheat, while the cor14b gene was mapped in Triticum monococcum on the long arm of chromosome 2A m . The analysis of single chromosome recombinant lines derived from a cross between Chinese Spring/Triticum spelta 5A and Chinese Spring/Cheyenne 5A identi®ed two loci with additive eects that are involved in the genetic control of cor14b mRNA accumulation. The ®rst locus was tightly linked to the marker psr911, while the second one was located between the marker Xpsr2021 and Frost resistance 1 (Fr1).

Hv-CBF2A overexpression in barley accelerates COR gene transcript accumulation and acquisition of freezing tolerance during cold acclimation

“…In comparison, the Ta-CBF14 and Ta-CBF15 overexpressing lines were grown using a 17/13°C day/night temperature differential under a 16 h light/8 h dark photoperiod regimen. Growth conditions very similar to the latter result in high COR14B transcript levels in freezing-tolerant lines and undetectable levels in freezing-sensitive lines, whereas no difference in COR14B accumulation occurs when plants are grown under a 25/20°C day/night temperature differential (Vágújfalvi et al 2000(Vágújfalvi et al , 2003. One possibility is that this temperature differential and the night time temperature in particular is having a large positive affect upon COR14B transcript accumulation in the Ta-CBF14 and Ta-CBF15 overexpressors whereas the constant 18°C used for gene expression analyses of the Hv-CBF2A overexpressing lines is not conducive for COR14B transcripts accumulation.…”

Advances in physiological and molecular aspects of plant cold tolerance

“…Pidal et al (2009) reported that main differences between winter and spring cereals genotypes in terms of vrn-1 characterization were insertions and deletions in the vrn-1 regions located in the promoter and first intron of this gene. However, it has been reported that the main two loci which control low-temperature tolerance in wheat are the frost resistance Fr-1 and Fr-2 (Vágújfalvi et al 2000). The locus of Fr-1 was reported to be closely connected to the vernalization locus Vrn1, which is well known to be the main controller of the transition of the vegetative to the reproductive meristem in response to low temperature (LaudenciaChingcuanco et al 2011).…”

Large deletions in the CBF gene cluster at the Fr-B2 locus are associated with reduced frost tolerance in wheat

“…The impact of the chromosome substitutions on frost tolerance was later found to be associated with the presence of the vernalization gene VRN-1 and the frost tolerance locus Fr-2, which were mapped ~30 cM apart on the long arms of homoeologous group 5 chromosomes (Vágújfalvi et al 2005;Vágújfalvi et al 2000;Vágújfalvi et al 2003). It was initially thought that an additional frost tolerance locus existed which was closely linked to VRN-1 (Fr-1), but it is now generally accepted that this is a pleiotropic effect of the earlier initiation of flowering caused by the dominant VRN-1 alleles .…”

“…Chromosome substitution experiments using the cold-hardy variety Cheyenne as a donor and the cold-susceptible variety Chinese Spring as a recipient, showed that transferring chromosomes 5A, 5D and, to a lesser extent, 5B conferred the greatest improvements in freezing tolerance (Sutka 1981;Veisz and Sutka 1989;Toth et al 2003). Using these same chromosome substitution lines, it was shown that chromosome 5A substitutions also conferred stronger induction of COR14b, a central cold responsive gene contributing to the protection of chloroplasts during exposure to freezing temperatures (Vágújfalvi et al 2000). This gene, as well as numerous other cold responsive genes, harbors a CRT-DRE box within its promoter, a conserved binding domain for the CBF (C-repeat Binding Factor) family of transcription factors.…”

“…Despite these large changes in global gene expression patterns, it appears that a relatively small number of loci account for a large proportion of the observed variance in cold tolerance between wheat varieties (Vágújfalvi et al 2000). Chromosome substitution experiments using the cold-hardy variety Cheyenne as a donor and the cold-susceptible variety Chinese Spring as a recipient, showed that transferring chromosomes 5A, 5D and, to a lesser extent, 5B conferred the greatest improvements in freezing tolerance (Sutka 1981;Veisz and Sutka 1989;Toth et al 2003).…”