Maize Genomics and Genetics 2024, Vol.15, No.3, 147-159 http://cropscipublisher.com/index.php/mgg 150 transposon families in Zea mays highlight the complexity and dynamism of the maize genome. Understanding these mechanisms is essential for elucidating the roles of transposons in genome evolution, gene regulation, and genetic diversity in maize. 4 Transposon Distribution and Abundance inZea Genomes 4.1 Genome-wide distribution patterns Transposable elements (TEs) are a significant component of the maize genome, constituting over 85% of its DNA sequence (Figure 1) (Stitzer et al., 2019). These elements are not uniformly distributed across the genome; instead, they exhibit distinct patterns of localization. For instance, certain TIR (Terminal Inverted Repeat) elements are less prevalent in centromeric and pericentromeric regions, while others do not show such biases (Su et al., 2019). This uneven distribution suggests that TEs may have specific insertion preferences or that certain genomic regions are more permissive to TE insertions. Figure 1 Chromosomal distribution of superfamilies and example families (Adopted from Stitzer et al., 2019) Image caption: Counts of number of insertions in 1 Mb bins across chromosome 1 for (A) TE superfamilies and (B-E) the 5 families with highest copy number in each of four superfamilies, DHH (B), DTT (C), RLC (D), and RLG (E) (Adopted from Stitzer et al., 2019) The dynamic nature of TE distribution is further highlighted by the observation that different TE families exhibit tissue-specific expression patterns. For example, a significant number of TE families are specifically active in pollen and endosperm, which are critical for reproductive processes (Anderson et al., 2019). This tissue-specific activity indicates that TEs may play roles in developmental regulation and genome evolution, contributing to the genetic diversity observed in maize.
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