The enigma of transposable element abundance: lessons from Arabidopsis

Transposable elements (TEs) represent a major component of diverse genomes, can generate large-effect mutations, and affect adaptive evolution. Despite their significant role in various evolutionary processes, the regulatory mechanisms governing TE abundance variation remain an enigma. This review synthesizes current knowledge about the evolutionary dynamics of TEs in natural populations of Arabidopsis, emphasizing forces driving TE abundance variation. In addition, we pay more attention to the influence of epigenetic factors and environmental stresses on TE activity and highlight the genetic architecture of TE transposition in natural populations. Finally, we review the progress in characterization, identification, and applications of active TEs, which are among the major contributors to TE abundance, and suggest directions for future study. Overall, we aim to resolve the enigma of TE abundance by outlining its potential drivers.