Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, Japan.
Forest Bio-Research Center, Forestry and Forest Products Research Institute, Hitachi, Ibaraki, Japan.
PLoS One. 2022 Jul 6;17(7):e0270522. doi: 10.1371/journal.pone.0270522. eCollection 2022.
The heartwood color of a major plantation tree Cryptomeria japonica shows high variability among clones and cultivars, and brighter heartwood has higher value in the usage of non-laminated wood such as in traditional construction, which makes heartwood color an important trait in breeding of this species. However, the genetic basis of the interactions between genetics and the environment on heartwood color has been understudied while these are necessary for effective breeding programs in multiple environmental condition. The objectives of the present study were to evaluate the effects of genetics and environments on heartwood color and how they interact in contrasting environments, and to identify genomic regions controlling heartwood color in C. japonica across multiple environments. Heartwood color in terms of Lab* color space and spectral reflectance was measured in common gardens established in three contrasting sites. Quantitative trait loci (QTL) that affect heartwood color were identified using previously constructed highly saturated linkage maps. Results found that heartwood color was largely genetically controlled, and genotype-by-environment interaction explained one-third of the total genetic variance of heartwood color. The effect of the environment was small compared to the effect of genetics, whereas environmental effects largely varied among heartwood color traits. QTL analysis identified a large number of QTLs with small to moderate effects (phenotypic variation explained of 6.6% on average). Some of these QTLs were stably expressed in multiple environments or had pleiotropic effects on heartwood color and moisture content. These results indicated that genetic variation in phenotypic plasticity plays an important role in regulating heartwood color and that the identified QTLs would maximize the breeding efficiency of heartwood color in C. japonica in heterogeneous environments.
主要人工林树种日本柳杉的心材颜色在无性系和品种之间表现出高度的可变性，而颜色较亮的心材在非层压木材的使用中具有更高的价值，如传统建筑，这使得心材颜色成为该物种选育的一个重要特征。然而，遗传与环境对心材颜色相互作用的遗传基础研究不足，而这些对于在多种环境条件下进行有效的选育计划是必要的。本研究的目的是评估遗传和环境对心材颜色的影响，以及它们在不同环境下的相互作用，并确定控制日本柳杉在多个环境下心材颜色的基因组区域。在三个不同地点建立的普通花园中，测量了心材颜色的 Lab*颜色空间和光谱反射率。使用先前构建的高度饱和的连锁图谱，鉴定了影响心材颜色的数量性状基因座（QTL）。结果发现，心材颜色主要受遗传控制，基因型与环境互作解释了心材颜色总遗传方差的三分之一。与遗传效应相比，环境效应较小，而环境效应在心材颜色性状之间差异很大。QTL 分析鉴定出了大量具有小到中等效应的 QTL（表型变异解释率平均为 6.6%）。其中一些 QTL 在多个环境中稳定表达或在心材颜色和水分含量上具有多效性。这些结果表明，表型可塑性的遗传变异在心材颜色的调节中起着重要作用，所鉴定的 QTL 将最大限度地提高日本柳杉在心材颜色在异质环境中的选育效率。
