Marguerit Elisa, Bouffier Laurent, Chancerel Emilie, Costa Paolo, Lagane Frédéric, Guehl Jean-Marc, Plomion Christophe, Brendel Oliver
University of Bordeaux, ISVV, EGFV, UMR 1287, F-33140 Villenave d'Ornon, France. INRA, ISVV, EGFV, UMR 1287, F-33140 Villenave d'Ornon, France. INRA, BIOGECO, UMR 1202, F-33610 Cestas, France.
INRA, BIOGECO, UMR 1202, F-33610 Cestas, France. University of Bordeaux, BIOGECO, UMR 1202, F-33400 Talence, France.
J Exp Bot. 2014 Sep;65(17):4757-68. doi: 10.1093/jxb/eru226. Epub 2014 Jul 1.
To meet the increasing demand of wood biomass worldwide in the context of climate change, developing improved forest tree varieties for high productivity in water-limited conditions is becoming a major issue. This involves breeding for genotypes combining high growth and moderate water loss and thus high water-use efficiency (WUE). The present work provides original data about the genetics of intrinsic WUE (the ratio between net CO2 assimilation rate and stomatal conductance, also estimated by carbon isotope composition of plant material; δ(13)C) and its relation to growth in Pinus pinaster Ait. First, heritability for δ(13)C was estimated (0.29) using a 15-year-old progeny trial (Landes provenance), with no significant differences among three sites contrasting in water availability. High intersite correlations (0.63-0.91) and significant but low genotype-environment interactions were detected. Secondly, the genetic architectures of δ(13)C and growth were studied in a three-generation inbred pedigree, introducing the genetic background of a more-drought-adapted parent (Corsican provenance), at ages of 2 years (greenhouse) and 9 years (plantation). One of the quantitative trait loci (QTLs) identified in the field experiment, explaining 67% of the phenotypic variance, was also found among the QTLs detected in the greenhouse experiment, where it colocalized with QTLs for intrinsic WUE and stomatal conductance. This work was able to show that higher WUE was not genetically linked to less growth, allowing thus genetic improvement of water use. As far as is known, the heritability and QTL effects estimated here are based on the highest number of genotypes measured to date.
在气候变化背景下，为满足全球对木材生物质日益增长的需求，培育在水分受限条件下具有高生产力的改良林木品种正成为一个重大问题。这涉及培育具有高生长量和适度水分损失从而具有高水分利用效率（WUE）的基因型。本研究提供了关于湿地松内在WUE（净CO2同化率与气孔导度之比，也可通过植物材料的碳同位素组成估算；δ(13)C）的遗传学及其与生长关系的原始数据。首先，利用一个15年生的子代试验（朗德种源）估算了δ(13)C的遗传力（0.29），在三个水分可利用性不同的地点之间没有显著差异。检测到较高的地点间相关性（0.63 - 0.91）以及显著但较低的基因型 - 环境互作。其次，在一个三代近交系谱中研究了δ(13)C和生长的遗传结构，引入了一个更耐旱亲本（科西嘉种源）的遗传背景，分别在2年生（温室）和9年生（种植园）时进行研究。在田间试验中鉴定出的一个解释67%表型变异的数量性状位点（QTL），在温室试验检测到的QTL中也被发现，它与内在WUE和气孔导度的QTL共定位。这项工作能够表明较高的WUE与较少的生长在遗传上没有联系，从而允许对水分利用进行遗传改良。据所知，这里估计的遗传力和QTL效应是基于迄今为止测量的最多基因型数量。
