title: Characterization of two novel cold-inducible K3 dehydrin genes from alfalfa (Medicago sativa spp. sativa L.).
abstract: Dehydrin defines a complex family of intrinsically disordered proteins with potential adaptive value with regard to freeze-induced cell dehydration. Search within an expressed sequence tags library from cDNAs of cold-acclimated crowns of alfalfa (Medicago sativa spp. sativa L.) identified transcripts putatively encoding K(3)-type dehydrins. Analysis of full-length coding sequences unveiled two highly homologous sequence variants, K(3)-A and K(3)-B. An increase in the frequency of genotypes yielding positive genomic amplification of the K(3)-dehydrin variants in response to selection for superior tolerance to freezing and the induction of their expression at low temperature strongly support a link with cold adaptation. The presence of multiple allelic forms within single genotypes and independent segregation indicate that the two K(3) dehydrin variants are encoded by distinct genes located at unlinked loci. The co-inheritance of the K(3)-A dehydrin with a Y(2)K(4) dehydrin restriction fragment length polymorphism with a demonstrated impact on freezing tolerance suggests the presence of a genome domain where these functionally related genes are located. These results provide additional evidence that dehydrin play important roles with regard to tolerance to subfreezing temperatures. They also underscore the value of recurrent selection to help identify variants within a large multigene family in allopolyploid species like alfalfa.
authors.affiliation: Crops and Soils Research and Development Center, Agriculture and Agri-Food Canada, 2560 Hochelaga Blvd., Quebec, QC, G1V 2J3, Canada.
authors.forename: Marie-Pier
authors.initials: MP
authors.lastname: Dubé
authors.forename: Yves
authors.initials: Y
authors.lastname: Castonguay
authors.forename: Jean
authors.initials: J
authors.lastname: Cloutier
authors.forename: Josée
authors.initials: J
authors.lastname: Michaud
authors.forename: Annick
authors.initials: A
authors.lastname: Bertrand
mesh_terms: D000064:Acclimatization / Q000235:genetics; D000595:Amino Acid Sequence; D015153:Blotting, Western; D003001:Cloning, Molecular; D019295:Computational Biology; D053938:DNA Fragmentation; D017931:DNA Primers; D018076:DNA, Complementary / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D020224:Expressed Sequence Tags; D005615:Freezing; D018506:Gene Expression Regulation, Plant; D015723:Gene Library; D056426:Genetic Loci; D005838:Genotype; D000455:Medicago sativa / Q000235:genetics*; D008969:Molecular Sequence Data; D005810:Multigene Family; D010641:Phenotype; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
chemical_list: D017931:DNA Primers; D018076:DNA, Complementary; D018744:DNA, Plant; D010940:Plant Proteins; C070556:dehydrin proteins, plant