Plant Gene and Trait 2024, Vol.15, No.2, 52-61 http://genbreedpublisher.com/index.php/pgt 54 activate detoxification pathways. These modifications can help trees to tolerate and survive in polluted environments, although the long-term effects of such epigenetic changes are still under investigation (Stuzin et al., 2000). Figure 1 Epigenetic factors in the adaptive strategies of trees under the influence of environmental changes (Adopted from Kurpisz and Pawłowski, 2022) Image caption: Climate change caused by environmental factors such as temperature, CO2 concentration, water supply, etc., can influence epigenetic regulations in the plant. This, in turn, may result in the adjustment of the mechanisms responsible for flowering or the seed germination and bud burst. FLC, Flowering Locus C; DOG1, Delay of Germination 1; TEFIIS, Translational Elongation Factor 2; HUB1, Histone Mono-ubiquitination 1; HIRA, Histone Regulator A; H3K4me3, trimethylation of lysine 4 on histone H3; and H3K27me3, trimethylation of lysine 27 on histone H3 (Adopted from Kurpisz and Pawłowski, 2022) 4 Case Studies: Epigenetic Responses to Environmental Stresses 4.1 Detailed examination of epigenetic changes under drought conditions Drought stress represents one of the most significant challenges for tree survival and productivity. Trees respond to drought through various physiological and molecular mechanisms, including epigenetic modifications. Studies have shown that drought conditions can lead to alterations in DNA methylation patterns, histone modifications, and changes in non-coding RNA expression (Figure 2) (Sow et al., 2021). One notable example is the response of oak (Quercus spp.) to prolonged drought periods. Research has demonstrated that drought stress induces hypermethylation at specific gene loci associated with water use efficiency and stress response pathways. These epigenetic changes are thought to contribute to the activation of genes involved in stomatal closure, osmotic adjustment, and antioxidative defense mechanisms. Furthermore, these modifications can be inherited, suggesting a potential role for epigenetic memory in drought resilience. Another case study involves poplar (Populus spp.), where drought conditions led to significant changes in histone acetylation levels at stress-responsive genes. These histone modifications facilitate a more open chromatin structure, promoting the rapid activation of genes essential for drought tolerance. This adaptive response underscores the dynamic nature of the epigenome in facilitating tree survival under water-limited conditions (Singh and Prasad, 2021; Kurpisz and Pawłowski, 2022).
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