Plant Gene and Trait 2024, Vol.15, No.2, 52-61 http://genbreedpublisher.com/index.php/pgt 55 Figure 2 General overview of the drought experiment on poplars (Populus tremula × Populus alba) (Adopted from Sow et al., 2021) Image caption: (a) Timeline of the experiment. Propagated in vitro plantlets from the wild-type (WT) and the two RNAi-ddm1 transgenic lines were acclimated in a heated glasshouse, transferred into 4 L pots and kept under control conditions until they were 3-months-old. At that time (t0), a waterd eficit was initiated for the plants assigned to the water deficit/rewatering treatment (WD-RW), while control plants were kept well-watered (WW). After 3 wk of water deficit (t1), plants of the WD-RW condition were rewatered to field capacity for 1 wk, after which the experiment ended (t2). The ecophysiological characterization of plant material was performed between t0 and t2. Sampling of shoot apical meristems (SAMs)for molecular analysis was performed at t2. (b) Overview of the plants in the glasshouse. (c) Examples of plant phenotypes at t2 under WW and WD-RW conditions for WT and RNAi-ddm1 lines (Adopted from Sow et al., 2021) 4.2 Effects of air pollution on epigenetic patterns in urban trees Urban environments expose trees to various pollutants, including particulate matter, heavy metals, and volatile organic compounds, all of which can impact their growth and health. Epigenetic modifications play a crucial role in enabling trees to cope with these stresses (Katsidi et al., 2023). A study on London plane trees (Platanus × acerifolia) in high-traffic urban areas revealed significant changes in DNA methylation patterns in response to air pollution. Increased methylation levels were observed at genes involved in detoxification and stress response pathways, suggesting an epigenetic mechanism for enhanced tolerance to pollutants. This epigenetic reprogramming allows urban trees to mitigate the detrimental effects of air pollution by modulating gene expression profiles in favor of stress adaptation and detoxification processes. In addition, research on black poplar (Populus nigra) exposed to industrial pollutants demonstrated alterations in histone modification patterns (Mukherjee et al., 2019). Specifically, histone methylation at stress-responsive gene promoters was increased, leading to the upregulation of genes involved in metal ion binding and oxidative stress defense. These findings highlight the importance of histone modifications in the epigenetic regulation of gene expression in response to environmental pollution (Locosselli et al., 2019).
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