In this article, we present the Cross Epigenetic Recycling (CER) hypothesis, which postulates a microbiome-based channel for RNA information transfer between mammals and plants via the soil. The central novelty is the relay model: miRNAs from mammalian waste-derived extracellular vesicles (EVs) enter the soil and are taken up by rhizosphere bacteria - particularly Pseudomonas spp. with a documented OMV/sRNA system - which repackage and retransmit the signal to plant root cells via outer membrane vesicles (OMVs). The model relies exclusively on biologically documented intermediate steps, each with at least one clear precedent in the literature. The proposed mechanistic window is the seed stage: the plant embryo exhibits the highest RNA-directed DNA methylation (RdDM) activity of any plant tissue, and RDR2-dependent amplification can fix exogenous RNA signals as permanent chromatin marks. Recent studies confirm bidirectional RNA transfer between mammalian cells and bacteria via EVs (Gröger et al., 2026) and between bacteria such as e.g. Pseudomonas and plants (Ravet et al., 2025), collectively strengthening the biological realism of the relay model. Additionally, we propose five testable predictions, including a negative control, an experimental design using apomictic Taraxacum officinale, incorporating sRNA-seq, ATAC-seq, UPLC-MS metabolomics, and rhizosphere microbiome sequencing, to test the CER model and explore its potential for non-GMO precision RNA agriculture.
Kukier et al. (2026) studied this question.