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First published online October 21, 2005; 10.1104/pp.105.068510 Plant Physiology 139:1304-1312 (2005) © 2005 American Society of Plant Biologists Genetic and Molecular Analyses of Natural Variation Indicate CBF2 as a Candidate Gene for Underlying a Freezing Tolerance Quantitative Trait Locus in Arabidopsis1,[w]Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología (Consejo Superior de Investigaciones Científicas), Cantoblanco, 28049 Madrid, Spain (C.A.-B., J.M.M.-Z.); Departamento de Biotecnología, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Carretera de A Coruña, 28040 Madrid, Spain (C.A.-B., C.G.-M., F.L., J.S., J.M.M.-Z.); Laboratory of Genetics, Wageningen University, NL6703 BD Wageningen, The Netherlands (M.K.); and Max Planck Institute for Plant Breeding Research, D50892 Cologne, Germany (M.K.)
Natural variation for freezing tolerance is a major component of adaptation and geographic distribution of plant species. However, little is known about the genes and molecular mechanisms that determine its naturally occurring diversity. We have analyzed the intraspecific freezing tolerance variation existent between two geographically distant accessions of Arabidopsis (Arabidopsis thaliana), Cape Verde Islands (Cvi) and Landsberg erecta (Ler). They differed in their freezing tolerance before and after cold acclimation, as well as in the cold acclimation response in relation to photoperiod conditions. Using a quantitative genetic approach, we found that freezing tolerance differences after cold acclimation were determined by seven quantitative trait loci (QTL), named FREEZING TOLERANCE QTL 1 (FTQ1) to FTQ7. FTQ4 was the QTL with the largest effect detected in two photoperiod conditions, while five other FTQ loci behaved as photoperiod dependent. FTQ4 colocated with the tandem repeated genes C-REPEAT BINDING FACTOR 1 (CBF1), CBF2, and CBF3, which encode transcriptional activators involved in the cold acclimation response. The low freezing tolerance of FTQ4-Cvi alleles was associated with a deletion of the promoter region of Cvi CBF2, and with low RNA expression of CBF2 and of several CBF target genes. Genetic complementation of FTQ4-Cvi plants with a CBF2-Ler transgene suggests that such CBF2 allelic variation is the cause of CBF2 misexpression and the molecular basis of FTQ4.
1 This work was supported by a Ramón y Cajal contract (to C.A.-B.), by the European Union project NATURAL (grant no. QLG2CT200101097), and by the Spanish Ministerio de Ciencia y Tecnología (grant nos. BIO20010344 and BIO200210133E). 2 These authors contributed equally to the paper. The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Carlos Alonso-Blanco (calonso{at}cnb.uam.es). [w] The online version of this article contains Web-only data. Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.105.068510. * Corresponding author; e-mail zapater{at}cnb.uam.es; fax 345854506. Received July 20, 2005; returned for revision August 24, 2005; accepted September 9, 2005. This article has been cited by other articles:
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