Dissecting transposon silencing through introduction of exogenous TEs

Fultz and Slotkin explore the question of how transposable element (TE) silencing is initiated. As they describe, there are two recognized mechanisms, one based on TE identity (meaning that it can be silenced through siRNAs initiated from a related TE, and in which de novo silencing can occur in the absence of mRNA production), and one based on expression level. To separate these pathways, the authors introduced exogenous TEs that have no sequence identity to TEs in the cell; this strategy therefore excludes the identity-based silencing pathway. Key findings include the different fates of full-length TEs as compared to TE fragments, and different outcomes when TEs are introduced by introgression (crossing) or direct transformation. Plant Cell 10.​1105/​tpc.​16.​00718