title: Molecular physiology and breeding at the crossroads of cold hardiness improvement.
abstract: Alfalfa (Medicago sativa L.) is a major forage legume grown extensively worldwide with important agronomic and environmental attributes. Insufficient cold hardiness is a major impediment to its reliable production in northern climates. Improvement of freezing tolerance using conventional breeding approaches is slowed by the quantitative nature of inheritance and strong interactions with the environment. The development of gene-based markers would facilitate the identification of genotypes with superior stress tolerance. Successive cycles of recurrent selection were applied using an indoor screening method to develop populations with significantly higher tolerance to freezing (TF). Bulk segregant analysis of heterogeneous TF populations identified DNA variations that are progressively enriched in frequency in response to selection. Polymorphisms resulting from intragenic variations within a dehydrin gene were identified and could potentially lead to the development of robust selection tools. Our results illustrate the benefits of feedback interactions between germplasm development programs and molecular physiology for a deeper understanding of the molecular and genetic bases of cold hardiness.
authors.affiliation: Soils and Crops Research Development Center, Agriculture and Agri-Food Canada, 2560 Hochelaga Boulevard, Sainte-Foy, Québec G1V 2J3, Canada. yves.castonguay@agr.gc.ca
authors.forename: Yves
authors.initials: Y
authors.lastname: Castonguay
authors.forename: Marie-Pier
authors.initials: MP
authors.lastname: Dubé
authors.forename: Jean
authors.initials: J
authors.lastname: Cloutier
authors.forename: Annick
authors.initials: A
authors.lastname: Bertrand
authors.forename: Réal
authors.initials: R
authors.lastname: Michaud
authors.forename: Serge
authors.initials: S
authors.lastname: Laberge
mesh_terms: D000064:Acclimatization; D001947:Breeding; D003080:Cold Temperature; D024861:Genetic Enhancement; D005819:Genetic Markers; D000455:Medicago sativa / Q000235:genetics* / Q000502:physiology*; D030821:Plants, Genetically Modified; D012641:Selection, Genetic; D013312:Stress, Physiological / Q000235:genetics
chemical_list: D005819:Genetic Markers