Triticeae Genomics and Genetics, 2024, Vol.15, No.5, 255-265 http://cropscipublisher.com/index.php/tgg 257 3 Major Epigenetic Mechanisms in Wheat 3.1 The role of DNA methylation DNA methylation is a crucial epigenetic mechanism that involves the addition of a methyl group to the cytosine residues in DNA, typically at CpG sites. This modification can lead to the repression of gene expression by altering the chromatin structure, making it less accessible to transcriptional machinery. In wheat, DNA methylation plays a significant role in regulating responses to environmental stresses such as drought, salinity, and pathogen attacks. For instance, methylation patterns can change in response to these stresses, thereby modulating the expression of stress-responsive genes to enhance plant resilience (Agarwal et al., 2020; Kong et al., 2020). Moreover, DNA methylation is involved in the regulation of developmental processes in wheat, such as flowering time and seed development. These processes are critical for crop yield and quality. By understanding and manipulating DNA methylation patterns, researchers aim to develop wheat varieties with improved traits, such as higher yield and better stress tolerance. This approach, known as epibreeding, leverages epigenetic variations to complement traditional breeding methods, offering a promising avenue for crop improvement (Samantara et al., 2021; Gupta and Salgotra, 2022). 3.2 Functions of histone modifications Histone modifications, including methylation, acetylation, phosphorylation, and ubiquitination, are post-translational modifications that occur on the histone proteins around which DNA is wrapped. These modifications can either activate or repress gene expression by altering the chromatin structure and recruiting specific regulatory proteins. In wheat, histone modifications are essential for regulating gene expression in response to both biotic and abiotic stresses. For example, histone acetylation is generally associated with gene activation and has been linked to the expression of genes involved in stress responses (Chang et al., 2019; Agarwal et al., 2020). Histone modifications also play a crucial role in developmental processes such as flowering and seed germination. These modifications can create a "memory" of environmental conditions, allowing wheat plants to better adapt to changing environments. The dynamic nature of histone modifications makes them a versatile tool for fine-tuning gene expression. Recent advances in understanding the cross-talk between different histone modifications have further highlighted their complex regulatory roles, offering new insights into how these modifications can be targeted for crop improvement (Molina-Serrano et al., 2013; Shafiq and Khan, 2015). 3.3 The relationship between wheat chromatin structure and trait expression The chromatin structure in wheat is a dynamic entity that can be remodeled in response to developmental cues and environmental signals. Chromatin remodeling involves changes in the positioning of nucleosomes, the basic units of chromatin, which can either facilitate or hinder access to the underlying DNA. This process is crucial for the regulation of gene expression and, consequently, for the expression of various traits in wheat. For instance, chromatin remodeling has been shown to play a role in the regulation of genes involved in stress responses, flowering time, and other important agronomic traits (Shafiq and Khan, 2015; Varotto et al., 2020). The relationship between chromatin structure and trait expression is also influenced by the interplay between DNA methylation and histone modifications. These epigenetic marks can work together to establish and maintain specific chromatin states that are conducive to either gene activation or repression. Understanding this interplay is essential for developing strategies to manipulate chromatin structure for crop improvement. By targeting specific chromatin remodeling factors or modifying epigenetic marks, researchers aim to enhance the expression of desirable traits in wheat, such as increased yield, improved stress tolerance, and better nutritional quality (Saravana Kumar et al., 2020; Samantara et al., 2021). 4 The Influence of Epigenetic Regulation on Agronomic Traits of Wheat 4.1 Regulation of yield traits in wheat Epigenetic modifications, such as DNA methylation and histone modifications, play a crucial role in regulating yield traits in wheat. These modifications can influence gene expression without altering the underlying DNA
RkJQdWJsaXNoZXIy MjQ4ODYzNQ==