Plants acquired a major retrotransposon horizontally from fungi during the conquest of land

Long-terminal repeat (LTR) retrotransposons are transposable elements that mobilize via RNA intermediates, and comprise a significant portion of land plant genomes. For example, LTR retrotransposons account for >4% of the Arabidopsis thaliana genome and >74.6% of the maize (Zea mays L.) genome (Peterson-Burch et al., 2004; Schnable et al., 2009). Typically, LTR retrotransposons have been classified into three major types, Ty1/Copia, Ty3/Gypsy, and Bel/Pao (Wells & Feschotte, 2020).