To avoid mutagenesis, the expression of retrotransposons in plant germ cells is repressed by various mechanisms, including post-transcriptionally by retrotransposon-derived short interfering RNAs (siRNAs). Martínez et al. investigated whether Arabidopsis thaliana sperm cell retrotransposons can be silenced by siRNAs that are produced in the pollen vegetative (non-reproductive) cell that surrounds sperm cells. They found that in RNAi-competent vegetative cells, a pollen retrotransposon-derived siRNA that can target a GFP transcript containing the siRNA target site caused its degradation into GFP-targeting secondary siRNAs, which in turn silenced the expression of another GFP transgene that was expressed in sperm cells. Furthermore, the expression of a GFP transgene containing the retrotransposon-derived siRNA target site was enabled in sperm cells upon the suppression of RNAi in the vegetative cell, demonstrating that endogenous siRNAs expressed in vegetative cells can repress retrotransposons in sperm cells.