Transcriptome-wide m6A methylation and metabolomic analysis reveal regulatory networks in rice roots under manganese stress

Rice (Oryza sativa) has a higher tolerance to manganese (Mn) stress than other cereals. However, the regulatory mechanisms governing Mn tolerance in rice remain poorly understood. In this work, seedlings of the rice cultivar Nipponbare were treated with 1.0 mM MnCl₂ for 10 days before root samples were collected for transcriptome-wide N⁶-methyladenosine (m⁶A) methylation and metabolome profiling. In the presence of extra Mn, we identified 2050 significantly modified m⁶A peaks and 2549 differentially expressed genes (DEGs). These DEGs were linked to key signaling pathways such as MAPK signaling, calcium signaling, and peroxides. Among these, 282 DEGs showed differential m⁶A methylation peaks, including 29 transcription factors, indicating they might be key upstream regulators of the Mn toxicity response. Furthermore, metabolomic research indicated considerable metabolic alterations in rice roots under Mn stress, notably in purine metabolism, amino acid biosynthesis, and glycerophospholipid metabolic pathways. Almost half of the metabolites were lipids or lipid-like compounds, indicating a potential function in signal transduction and membrane biogenesis. The findings lead to a better understanding of regulatory networks in rice roots that aid in Mn stress tolerance.