Cobo-Simón Irene, Gómez-Garrido Jèssica, Esteve-Codina Anna, Dabad Marc, Alioto Tyler, Maloof Julin N, Méndez-Cea Belén, Seco José Ignacio, Linares Juan Carlos, Gallego Francisco Javier
Department of Physical, Chemical and Natural Systems. University Pablo de Olavide, Seville, Spain.
Department of Genetics, Physiology and Microbiology, Genetics Unit. Faculty of Biological Sciences, Complutense University of Madrid, Madrid, Spain.
Front Plant Sci. 2023 Apr 19;14:1116863. doi: 10.3389/fpls.2023.1116863. eCollection 2023.
Understanding the adaptive capacity to current climate change of drought-sensitive tree species is mandatory, given their limited prospect of migration and adaptation as long-lived, sessile organisms. Knowledge about the molecular and eco-physiological mechanisms that control drought resilience is thus key, since water shortage appears as one of the main abiotic factors threatening forests ecosystems. However, our current background is scarce, especially in conifers, due to their huge and complex genomes.
Here we investigated the eco-physiological and transcriptomic basis of drought response of the climate change-threatened conifer . We studied seedlings from two locations with contrasting drought conditions to investigate a local adaptation. Seedlings were subjected to experimental drought conditions, and were monitored at immediate (24 hours) and extended (20 days) times. In addition, post-drought recovery was investigated, depicting two contrasting responses in both locations (drought resilient and non-resilient). Single nucleotide polymorphisms (SNPs) were also studied to characterize the genomic basis of drought resilience and investigate a rapid local adaptation of .
transcriptome assembly was performed for the first time in this species, providing differences in gene expression between the immediate and extended treatments, as well as among the post-drought recovery phenotypes. Weighted gene co-expression network analysis showed a regulation of stomatal closing and photosynthetic activity during the immediate drought, consistent with an isohydric dynamic. During the extended drought, growth and flavonoid biosynthesis inhibition mechanisms prevailed, probably to increase root-to-shoot ratio and to limit the energy-intensive biosynthesis of secondary metabolites. Drought sensitive individuals failed in metabolism and photosynthesis regulation under drought stress, and in limiting secondary metabolite production. Moreover, genomic differences (SNPs) were found between drought resilient and sensitive seedlings, and between the two studied locations, which were mostly related to transposable elements.
This work provides novel insights into the transcriptomic basis of drought response of , a set of candidate genes mechanistically involved in its drought sensitivity and evidence of a rapid local adaptation. Our results may help guide conservation programs for this threatened conifer, contribute to advance drought-resilience research and shed light on trees' adaptive potential to current climate change.
鉴于干旱敏感型树种作为长寿、固着生物，其迁移和适应前景有限，了解它们对当前气候变化的适应能力至关重要。由于缺水是威胁森林生态系统的主要非生物因素之一，因此掌握控制干旱恢复力的分子和生态生理机制是关键。然而，由于针叶树基因组庞大且复杂，我们目前在这方面的背景知识匮乏。
在此，我们研究了受气候变化威胁的针叶树干旱响应的生态生理和转录组学基础。我们研究了来自两个干旱条件不同地点的幼苗，以探究局部适应性。对幼苗施加实验性干旱条件，并在即时（24小时）和延长（20天）时间点进行监测。此外，还研究了干旱后恢复情况，描绘了两个地点的两种不同反应（干旱恢复型和非恢复型）。还研究了单核苷酸多态性（SNP），以表征干旱恢复力的基因组基础，并探究该针叶树的快速局部适应性。
首次对该物种进行了转录组组装，揭示了即时和延长处理之间以及干旱后恢复表型之间的基因表达差异。加权基因共表达网络分析表明，在即时干旱期间气孔关闭和光合活性受到调控，这与等水动态一致。在延长干旱期间，生长和类黄酮生物合成抑制机制占主导，可能是为了增加根冠比并限制次生代谢物的高能耗生物合成。干旱敏感个体在干旱胁迫下无法调节代谢和光合作用，也无法限制次生代谢物的产生。此外，在干旱恢复型和敏感型幼苗之间以及两个研究地点之间发现了基因组差异（SNP），这些差异大多与转座元件有关。
这项工作为该针叶树干旱响应的转录组学基础提供了新见解，一组候选基因在其干旱敏感性中发挥了机制作用，并提供了快速局部适应性的证据。我们的结果可能有助于指导针对这种受威胁针叶树的保护计划，推动干旱恢复力研究，并揭示树木对当前气候变化的适应潜力。
