Subcellular Distribution of Brominated Flame Retardants in Rice Governs Root-to-Shoot Translocation via a DNA Methylation-Mediated Multilayered Regulatory Network

Brominated flame retardants (BFRs) in soil can be absorbed
by crops
and enter the food chain, posing risks to food safety and human health.
Understanding how plants manage BFR uptake and translocation is key
to risk control. This study compared two rice japonica cultivars with
contrasting BFR accumulation: a tolerant cultivar (TOL) and a sensitive
cultivar (SENS). Subcellular localization revealed that TOL sequestered
more BFRs in root cell walls and cytoplasm, limiting upward translocation,
whereas SENS accumulated more in cell organelles. Spatial colocalization
analysis of reactive oxygen species (ROS) and nuclei showed that ROS
signals were highly concentrated around nuclei in SENS, suggesting
oxidative challenge, while spatially decoupled in TOL. Integrated
multiomics revealed a molecular cascade: TOL reduced genome-wide DNA
methylation, activating cell wall and lipid homeostasis genes (e.g.,
CL4, CCR). This boosted phenylpropanoid pathway products (e.g., flavonoids;
fold change = 2.04–19.4), thickening cell walls and enhancing
BFR sequestration. In contrast, SENS showed hypermethylation of lignin-
and gibberellin-related genes, weakening physical defense and disrupting
the growth-defense balance. These findings highlight that epigenetic
regulatory network stability is crucial for stress adaptation. Precision
epigenetic editing could help develop high-yielding, pollution-resilient
crops, offering a strategy for sustainable agriculture in contaminated
areas.