TY - JOUR
T1 - Regulation of freezing tolerance and flowering in temperate cereals
T2 - The VRN-1 connection
AU - Dhillon, Taniya
AU - Pearce, Stephen P.
AU - Stockinger, Eric J.
AU - Distelfeld, Assaf
AU - Li, Chengxia
AU - Knox, Andrea K.
AU - Vashegyi, Ildikó
AU - Galiba, Gabor
AU - Vágú, Attila
AU - Dubcovsky, Jorge
PY - 2010/8/1
Y1 - 2010/8/1
N2 - In winter wheat (Triticum spp.) and barley (Hordeum vulgare) varieties, long exposures to nonfreezing cold temperatures accelerate flowering time (vernalization) and improve freezing tolerance (cold acclimation). However, when plants initiate their reproductive development, freezing tolerance decreases, suggesting a connection between the two processes. To better understand this connection, we used two diploid wheat (Triticum monococcum) mutants, maintained vegetative phase (mvp), that carry deletions encompassing VRN-1, the major vernalization gene in temperate cereals. Homozygous mvp/mvp plants never flower, whereas plants carrying at least one functional VRN-1 copy (Mvp/2) exhibit normal flowering and high transcript levels of VRN-1 under long days. The Mvp/2 plants showed reduced freezing tolerance and reduced transcript levels of several cold-induced C-REPEAT BINDING FACTOR transcription factors and COLD REGULATED genes (COR) relative to the mvp/ mvp plants. Diploid wheat accessions with mutations in the VRN-1 promoter, resulting in high transcript levels under both long and short days, showed a significant down-regulation of COR14b under long days but not under short days. Taken together, these studies suggest that VRN-1 is required for the initiation of the regulatory cascade that down-regulates the cold acclimation pathway but that additional genes regulated by long days are required for the down-regulation of the COR genes. In addition, our results show that allelic variation in VRN-1 is sufficient to determine differences in freezing tolerance, suggesting that quantitative trait loci for freezing tolerance previously mapped on this chromosome region are likely a pleiotropic effect of VRN-1 rather than the effect of a separate closely linked locus (FROST RESISTANCE-1), as proposed in early freezing tolerance studies.
AB - In winter wheat (Triticum spp.) and barley (Hordeum vulgare) varieties, long exposures to nonfreezing cold temperatures accelerate flowering time (vernalization) and improve freezing tolerance (cold acclimation). However, when plants initiate their reproductive development, freezing tolerance decreases, suggesting a connection between the two processes. To better understand this connection, we used two diploid wheat (Triticum monococcum) mutants, maintained vegetative phase (mvp), that carry deletions encompassing VRN-1, the major vernalization gene in temperate cereals. Homozygous mvp/mvp plants never flower, whereas plants carrying at least one functional VRN-1 copy (Mvp/2) exhibit normal flowering and high transcript levels of VRN-1 under long days. The Mvp/2 plants showed reduced freezing tolerance and reduced transcript levels of several cold-induced C-REPEAT BINDING FACTOR transcription factors and COLD REGULATED genes (COR) relative to the mvp/ mvp plants. Diploid wheat accessions with mutations in the VRN-1 promoter, resulting in high transcript levels under both long and short days, showed a significant down-regulation of COR14b under long days but not under short days. Taken together, these studies suggest that VRN-1 is required for the initiation of the regulatory cascade that down-regulates the cold acclimation pathway but that additional genes regulated by long days are required for the down-regulation of the COR genes. In addition, our results show that allelic variation in VRN-1 is sufficient to determine differences in freezing tolerance, suggesting that quantitative trait loci for freezing tolerance previously mapped on this chromosome region are likely a pleiotropic effect of VRN-1 rather than the effect of a separate closely linked locus (FROST RESISTANCE-1), as proposed in early freezing tolerance studies.
UR - http://www.scopus.com/inward/record.url?scp=77955668801&partnerID=8YFLogxK
U2 - 10.1104/pp.110.159079
DO - 10.1104/pp.110.159079
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AN - SCOPUS:77955668801
SN - 0032-0889
VL - 153
SP - 1846
EP - 1858
JO - Plant Physiology
JF - Plant Physiology
IS - 4
ER -