Plant, Animal & Microbe Genomes X Conference

January 12-16, 2002
Town & Country Convention Center
San Diego, CA

Workshop: Arabidopsis
            

NATURALLY-OCCURING VARIATION FOR FREEZING TOLERANCE IN ARABIDOPSIS

¹ Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología, Campus de la UAM , 28049 Madrid, Spain

² Departamento de Biotecnología, INIA, Ctra. de La Coruña Km 7, 28040 Madrid, Spain

³ Department of Genetics, Wageningen University, 6703 HA Wageningen, The Netherlands

Arabidopsis plants can survive freezing temperatures when are previously exposed to low chilling temperatures. In order to identify the genetic determinants responsible for adaptation to freezing conditions we have searched for natural variation in freezing tolerance among several Arabidopsis ecotypes. Most of the analysed ecotypes developed high levels of freezing tolerance after exposure to low temperature during one week. However, the ecotype Cvi, from the Cape Verde islands, showed an impaired development of freezing tolerance under the same conditions as well as a reduction in the expression of cold regulated genes. A quantitative genetic analysis performed on recombinant inbred lines derived from the cross between Ler and Cvi indicated that differences in freezing tolerance between these two ecotypes can be mainly attributed to QTLs on chromosomes 1, 4 and 5. Analysis of the Arabidopis genome sequence around the QTL on chromosome 4 identified the CBF genes encoding the C-repeat/DRE Binding Factors as candidate genes responsible for this QTL. This hypothesis is supported by the nucleotide sequence polymorphisms between Ler and Cvi characterised in this region as well as the complementation of the freezing sensitive phenotype with a cosmid containing the CBF genes.