Research identifies an OVERACHIEVER methyltransferase that generates m3U2952 methylation in the peptidyl transferase center (PTC) of 25S rRNA in Arabidopsis.[1][2][3] This methylation allows stable binding of the thermospermine polyamine to a specific site in the PTC that connects the P-site tRNA to the 15 rRNA residues.[1][2] Thermospermin acts bifunctionally: it increases the translation of SAC51 and SAC51-LIKEs (SACLs), which inhibit the heterodimerization of the transcription factors LHW and TARGET-OF-MONOPTEROS5, thereby preventing the differentiation of xylem vessels.[1][2][3] At the same time, it inhibits the translation of LHW.[2][3] In mutants lacking m3U2952 methylation, thermospermin cannot stably bind, resulting in high translation of LHW and disruption of vascular patterning.[2] Study reveals dependence between conserved rRNA methylation and polyamine in controlling xylem cell fate.[1][3][4]