title: Genetic variability and QTL mapping of freezing tolerance and related traits in Medicago truncatula.
abstract: Freezing is a major environmental limitation to crop productivity for a number of species including legumes. We investigated the genetic determinism of freezing tolerance in the model legume Medicago truncatula Gaertn (M. truncatula). After having observed a large variation for freezing tolerance among 15 M. truncatula accessions, the progeny of a F6 recombinant inbred line population, derived from a cross between two accessions, was acclimated to low above-freezing temperatures and assessed for: (a) number of leaves (NOL), leaf area (LA), chlorophyll content index (CCI), shoot and root dry weights (SDW and RDW) at the end of the acclimation period and (b) visual freezing damage (FD) during the freezing treatment and 2 weeks after regrowth and foliar electrolyte leakage (EL) 2 weeks after regrowth. Consistent QTL positions with additive effects for FD were found on LG1, LG4 and LG6, the latter being the most explanatory (R (2) ≈ 40 %). QTL for NOL, QTL for EL, NOL and RDW, and QTL for EL and CCI colocalized with FD QTL on LG1, LG4 and LG6, respectively. Favorable alleles for these additive effects were brought by the same parent suggesting that this accession contributes to superior freezing tolerance by affecting plants' capacity to maintain growth at low above-freezing temperatures. No epistatic effects were found between FD QTL, but for each of the studied traits, 3-6 epistatic effects were detected between loci not detected directly as QTL. These results open the way to the assessment of syntenic relationships between QTL for frost tolerance in M. truncatula and cultivated legume species.
authors.affiliation: Institut National de la Recherche Agronomique, UMR 1281 SADV, Estrées-Mons, Péronne Cedex, France.
authors.forename: Komlan
authors.initials: K
authors.lastname: Avia
authors.forename: Marie-Laure
authors.initials: ML
authors.lastname: Pilet-Nayel
authors.forename: Nasser
authors.initials: N
authors.lastname: Bahrman
authors.forename: Alain
authors.initials: A
authors.lastname: Baranger
authors.forename: Bruno
authors.initials: B
authors.lastname: Delbreil
authors.forename: Véronique
authors.initials: V
authors.lastname: Fontaine
authors.forename: Céline
authors.initials: C
authors.lastname: Hamon
authors.forename: Eric
authors.initials: E
authors.lastname: Hanocq
authors.forename: Martine
authors.initials: M
authors.lastname: Niarquin
authors.forename: Hélène
authors.initials: H
authors.lastname: Sellier
authors.forename: Christophe
authors.initials: C
authors.lastname: Vuylsteker
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Prosperi
authors.forename: Isabelle
authors.initials: I
authors.lastname: Lejeune-Hénaut
mesh_terms: D000064:Acclimatization / Q000235:genetics; D002734:Chlorophyll / Q000032:analysis; D002874:Chromosome Mapping / Q000379:methods*; D004843:Epistasis, Genetic; D005615:Freezing; D017343:Genes, Plant; D008040:Genetic Linkage; D014644:Genetic Variation; D018525:Germination; D046913:Medicago truncatula / Q000235:genetics* / Q000254:growth & development; D010641:Phenotype; D017440:Photoperiod; D018517:Plant Roots / Q000235:genetics; D040641:Quantitative Trait Loci
chemical_list: D002734:Chlorophyll