Genetic variability and QTL mapping of freezing tolerance and related traits in [i]Medicago truncatula[/i]

Komlan Avia (1, 2) , Marie-Laure Pilet-Nayel (3) , Nasser Bahrman (1) , Alain Baranger (3) , Bruno Delbreil (1) , Véronique Fontaine (1) , Céline Hamon (3) , Eric Hanocq (1) , Martine Niarquin (1) , Hélène Sellier-Richard (1) , Christophe Vuylsteker (1) , Jean-Marie Prosperi (4) , Isabelle Lejeune-Henaut (1)

1 SADV - Stress Abiotiques et Différenciation des Végétaux Cultivés
2 Department of Biology, Plant Genetics Group
3 IGEPP - Institut de Génétique, Environnement et Protection des Plantes
4 UMR AGAP - Amélioration génétique et adaptation des plantes méditerranéennes et tropicales

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) a parts per thousand 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.

Mots clés: oilseed brassica; frost tolerance; linkage maps; loci; alfalfa; intracellular substances; winter hardiness; cold acclimation; hordeum vulgare l; low temperature tolerance

Domaines: Sciences du Vivant [q-bio]

Komlan Avia, Marie-Laure Pilet-Nayel, Nasser Bahrman, Alain Baranger, Bruno Delbreil, et al.. Genetic variability and QTL mapping of freezing tolerance and related traits in [i]Medicago truncatula[/i]. TAG Theoretical and Applied Genetics, 2013, 126 (9), pp.2353-2366. ⟨10.1007/s00122-013-2140-7⟩. ⟨hal-01208635⟩