BIOGECO, INRAE, University of Bordeaux, 33610, Cestas, France.
CIRAD, UMR AGAP, F-34398, Montpellier, France.
Plant J. 2020 Jul;103(1):338-356. doi: 10.1111/tpj.14734. Epub 2020 Apr 13.
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.
树木的脉搏（茎半径波动的日周期）已被广泛研究，作为分析树木对环境响应的一种方法，包括树木水分关系的表型可塑性。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得到探索。我们通过监测 210 棵尾巨桉×尾叶桉全同胞家系在 2 年期间的每日茎半径波动（dSRF），来描述这种响应的遗传和环境决定因素。dSRF 信号被分解为水力电容，评估为收缩的每日幅度（DA），净生长，估计为两天之间最大半径的变化（ΔR）。这两个特征的环境决定因素明显不同：DA 与与水分需求有关的大气变量呈正相关，而ΔR 与土壤含水量有关。这两个特征的遗传力在时间上从低到中等不等，揭示了一种随时间或环境变化的复杂遗传决定因素。我们鉴定了 686 个和 384 个代表 DA 和ΔR 的 32 个和 31 个每日数量性状基因座（QTL），分别。鉴定这两个性状的 27 个主要基因组区域的基因网络，为涉及水分需求和供应的生物机制提供了更多假设。这项研究强调了树木中受环境诱导的每日茎半径波动变化是由遗传控制的，并表明这些随时间积累的日常响应塑造了成熟特征的遗传结构。
