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Abstract：
The pulse of the tree (diurnal cycle of stem radius fluctuations) has been widely studied as a way of analyzing tree responses to the environment, including the phenotypic plasticity of tree-water relationships in particular. However, the genetic basis of this daily phenotype and its interplay with the environment remain largely unexplored. We characterized the genetic and environmental determinants of this response, by monitoring daily stem radius fluctuation (dSRF) on 210 trees from a Eucalyptus urophylla × E. grandis full-sib family over 2 years. The dSRF signal was broken down into hydraulic capacitance, assessed as the daily amplitude of shrinkage (DA), and net growth, estimated as the change in maximum radius between two consecutive days (ΔR). The environmental determinants of these two traits were clearly different: DA was positively correlated with atmospheric variables relating to water demand, while ΔR was associated with soil water content. The heritability for these two traits ranged from low to moderate over time, revealing a time-dependent or environment-dependent complex genetic determinism. We identified 686 and 384 daily quantitative trait loci (QTL) representing 32 and 31 QTL regions for DA and ΔR, respectively. The identification of gene networks underlying the 27 major genomics regions for both traits generated additional hypotheses concerning the biological mechanisms involved in response to water demand and supply. This study highlights that environmentally induced changes in daily stem radius fluctuation are genetically controlled in trees and suggests that these daily responses integrated over time shape the genetic architecture of mature traits.
摘要：
树的脉冲（茎半径波动的日周期）已被广泛研究，作为分析树木对环境的反应的一种方式，特别包括树水关系的表型可塑性。然而,这种日常表型的遗传基础及其与环境的相互作用在很大程度上仍未被探索。我们表征了这种反应的遗传和环境决定因素，通过在2年内监测尾叶桉树×E.grandis全同胞家庭的210棵树上的每日茎半径波动（dSRF）。dSRF信号被分解成液压电容，评估为每日收缩幅度(DA)，净增长，估计为连续两天之间的最大半径变化(ΔR)。这两个性状的环境决定因素明显不同：DA与与水需求有关的大气变量呈正相关，而ΔR与土壤含水量有关。随着时间的推移，这两个性状的遗传力范围从低到中等，揭示了时间依赖或环境依赖的复杂遗传决定论。我们确定了686和384个每日数量性状基因座（QTL），分别代表DA和ΔR的32和31个QTL区域，分别。对这两个性状的27个主要基因组学区域的基因网络的识别产生了有关对水的需求和供应做出反应所涉及的生物学机制的其他假设。这项研究强调了环境引起的每日茎半径波动变化在树木中受到遗传控制，并表明这些随着时间的推移整合的每日反应塑造了成熟性状的遗传结构。
