Institut National de la Recherche Agronomique, UMR 1281 SADV, Estrées-Mons, Péronne Cedex, France.
Theor Appl Genet. 2013 Sep;126(9):2353-66. doi: 10.1007/s00122-013-2140-7. Epub 2013 Jun 19.
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.
冷冻是包括豆类植物在内的许多物种作物生产力的主要环境限制因素。我们研究了模式豆科植物蒺藜苜蓿（Medicago truncatula Gaertn）（M. truncatula）的抗冻性遗传决定因素。在观察到 15 个蒺藜苜蓿品系的抗冻性存在很大差异之后，从两个品系杂交产生的 F6 重组自交系群体的后代在适应较低的超冰点温度后，对以下参数进行了评估：（a）叶片数（NOL）、叶面积（LA）、叶绿素含量指数（CCI）、地上部和根干重（SDW 和 RDW）在适应期结束时，（b）在冷冻处理期间和再生后 2 周的叶片可见冻害（FD）以及再生后 2 周的叶片电解质泄漏（EL）。在 LG1、LG4 和 LG6 上发现了与 FD 具有加性效应的一致 QTL 位置，后者具有最强的解释力（R²≈40%）。与 FD 共定位的 QTL 还有 NOL、EL、NOL 和 RDW、EL 和 CCI，分别位于 LG1、LG4 和 LG6 上。这些加性效应的有利等位基因来自同一亲本，表明该品系通过影响植物在较低超冰点温度下保持生长的能力来提高抗冻性。在 FD QTL 之间未发现上位性效应，但对于每个研究性状，在未直接作为 QTL 检测到的基因座之间检测到 3-6 个上位性效应。这些结果为评估蒺藜苜蓿耐霜性 QTL 与栽培豆科植物之间的同线性关系铺平了道路。
