tRNA-m1A methylation controls the infection of Magnaporthe oryzae by supporting ergosterol biosynthesis

Abstract

Ergosterols are essential components of fungal plasma membranes. Inhibitors targeting ergosterol biosynthesis (ERG) genes are critical for controlling fungal pathogens, including Magnaporthe oryzae, the fungus that causes rice blast. However, the translational mechanisms governing ERG gene expression remain largely unexplored. Here, we show that the Trm6/Trm61 complex catalyzes dynamic N¹-methyladenosine at position 58 (m¹A58) in 51 transfer RNAs (tRNAs) of M. oryzae, significantly influencing translation at both the initiation and elongation stages. Notably, tRNA m¹A58 promotes elongation speed at most cognate codons mainly by enhancing eEF1-tRNA binding rather than affecting tRNA abundance or charging. The absence of m¹A58 leads to substantial decreases in the translation of ERG genes, ergosterol production, and, consequently, fungal virulence. Simultaneously targeting the Trm6/Trm61 complex and the ergosterol biosynthesis pathway markedly improves rice blast control. Our findings demonstrate an important role of m¹A58-mediated translational regulation in ergosterol production and fungal infection, offering a potential strategy for fungicide development.

Keywords: Magnaporthe oryzae; codon usage; ergosterol biosynthesis; fungal pathogens; fungicide; m(1)A methylation; tRNA modification; translation elongation; translation initiation; translational regulation.