Triticeae Genomics and Genetics, 2024, Vol.15, No.1, 31-43 http://cropscipublisher.com/index.php/lgg 31 Review and Progress Open Access Role of Transposable Elements in the Evolution of the Triticeae Genome Jianhui Li 1 , Renxiang Cai 2 1 Institute of Life Science, Jiyang College of Zhejiang A&F University, Zhuji, 311800, Zhejiang, China 2 Zhejiang Agronomist College, Hangzhou, 310021, Zhejiang, China Corresponding author: garen.jh.li@foxmail.com Triticeae Genomics and Genetics, 2024, Vol.15, No.1 doi: 10.5376/tgg.2024.15.0004 Received: 02 Jan., 2024 Accepted: 03 Feb., 2024 Published: 14 Feb., 2024 Copyright © 2024 Li and Cai, This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Preferred citation for this article: Li J.H., and Cai R.X., 2024, Role of transposable elements in the evolution of the Triticeae genome, Triticeae Genomics and Genetics, 15(1): 31-43 (doi: 10.5376/tgg.2024.15.0004) Abstract Transposable elements (TEs) are ubiquitous components of genomes and play a significant role in the evolution and diversification of the Triticeae tribe, which includes important cereal crops such as wheat, barley, and rye. This research examines the impact of TEs on Triticeae genome evolution, exploring their contribution to genome size, structure, and genetic diversity. We discuss the classification and mechanisms of TEs, focusing on their role in genome expansion, gene regulation, and the creation of new regulatory networks. Case studies in Triticeae species highlight the dynamic nature of TEs and their influence on genomic architecture and evolutionary adaptation. Advances in sequencing technologies and bioinformatics tools have enhanced our understanding of TE diversity and activity, paving the way for new discoveries and potential applications in crop improvement. This research underscores the importance of continued research into TEs to fully elucidate their roles and harness their potential for agricultural and biotechnological advancements. Keywords Transposable elements; Triticeae genome; Genome evolution; Retrotransposons; Genetic diversity The Triticeae tribe, belonging to the Poaceae family, encompasses some of the most agriculturally significant cereal crops, including wheat (Triticumspp.): barley (Hordeumspp.): and rye (Secale spp.). The Triticeae tribe is characterized by its genetic diversity and adaptability, which have enabled these species to thrive in various environmental conditions. These crops are foundational to global agriculture, supplying staple food sources for human consumption and livestock feed, thereby significantly contributing to food security and the agricultural economy worldwide (Li et al., 2004). The genomes of Triticeae species are notably large and complex, with a significant portion composed of repetitive sequences. This genetic diversity, driven by polyploidization, mutations, and the activity of transposable elements (TEs): is vital for the adaptability and resilience of these crops, enabling them to withstand diverse environmental conditions and resist various biotic and abiotic stresses (Middleton et al., 2013). For instance, the wheat genome, one of the largest among Triticeae, is approximately 15 Gb in size and is predominantly hexaploid, containing three sets of homologous chromosomes (AABBDD) (Papon et al., 2023). A striking feature of these genomes is the high proportion of transposable elements (TEs): which constitute over 80% of the wheat genome (Wicker et al., 2018; Zhang et al., 2021). This extensive presence of TEs contributes to the genetic diversity and evolutionary dynamics of Triticeae species. Transposable elements (TEs) are DNA sequences that can change their position within the genome, thereby creating or reversing mutations and altering the cell's genetic identity. They are categorized into two main types: Class I elements, or retrotransposons, which move via an RNA intermediate, and Class II elements, or DNA transposons, which operate through a "cut-and-paste" mechanism. Retrotransposons include long terminal repeat (LTR) elements and non-LTR elements, while DNA transposons can be autonomous, carrying the necessary machinery for their movement, or non-autonomous, relying on external transposase enzymes for transposition (Thiyagarajan et al., 2022). Within these classes, TEs are further divided into various families based on their structural characteristics and mechanisms of transposition. In Triticeae genomes, TEs constitute a significant portion, with retrotransposons like LTRs being particularly abundant (Sabot and Schulman, 2009).
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