An mRNA methylase and demethylase regulate sorghum salt tolerance by mediating N6-methyladenosine modification

N-6-methyladenosine (m(6)A) modification is a crucial and widespread molecular mechanism governing plant development and stress tolerance. The specific impact of m(6)A regulation on plants with inherently high salt tolerance remains unclear. Existing research primarily focuses on the overexpression or knockout of individual writer or eraser components to alter m(6)A levels. However, a comprehensive study simultaneously altering overall m(6)A modification levels within the same experiment is lacking. Such an investigation is essential to determine whether opposing changes in m(6)A modification levels exert entirely different effects on plant salt tolerance. In this study, we identified the major writer member mRNA adenosine methylase A (SbMTA) in sorghum (Sorghum bicolor) as critical for sorghum survival. The sbmta mutant exhibits a phenotype characterized by reduced overall m(6)A, developmental arrest, and, ultimately, lethality. Overexpression of SbMTA increased m(6)A levels and salt tolerance, while overexpression of the m(6)A eraser alkylated DNA repair protein AlkB homolog 10B (SbALKBH10B) in sorghum showed the opposite phenotype. Comparative analyses between sorghum with different m(6)A levels reveal that SbMTA- and SbALKBH10B-mediated m(6)A alterations significantly impact the stability and expression levels of genes related to the abscisic acid signaling pathway and growth under salt stress. In summary, this study unveils the intricate relationship between m(6)A modifications and salt tolerance in sorghum, providing valuable insights into how m(6)A modification levels on specific transcripts influence responses to salt stress.