2,2′,4,4′-Tetrabromodiphenyl ether and copper disturbed the source-to-sink allocation of sucrose in rice through regulating the NAC23-Tre6P-SnRK1a signaling pathway

The co-occurrence of 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) and copper (Cu) in agricultural fields pose significant implications for crop growth and grain production. This study explored their individual and combined effects on rice crops and elucidated the underlying mechanisms combining in vivo, in vitro, and in silico investigations. Both BDE-47 and Cu inhibited shoot biomass, whereas root biomass exhibited distinct profiles: BDE-47 inhibited it, while Cu promoted it, at environmentally relevant exposure concentrations. This phenomenon was attributed to differences in sucrose transport between the source (shoot) and sink (root). Furthermore, metabolic, transcriptional, and translational analyses unveiled that this process was modulated by the NAC23-Tre6P-SnRK1a signaling pathway, with the dysfunction of fructose-1,6-diphosphate aldolase (FBA) and alterations in intracellular sucrose level serving as the crucial negative factors. Both contaminants bound to FBA, disrupting glucose signal transmission and upregulating SnRK1a expression. Additionally, BDE-47 suppressed sucrose levels, thereby reducing NAC23 activity and inhibiting sucrose transport. Conversely, Cu significantly elevated sucrose levels, mitigating the adverse effects of SnRK1a on NAC23 and enhancing sucrose transport. Interestingly, the coexistence of Cu with BDE-47 synergistically inhibited sucrose transport, further reducing root biomass and lowering the toxicity threshold of BDE-47 on rice crops. This study offered novel insights into the signaling regulatory mechanisms governing the differential impacts of BDE-47 and Cu on rice growth and yield production, facilitating more accurate assessments of their phytotoxicity and informing scientific regulatory frameworks for croplands.