3.3 BPH infestation decreased rice m6A methylation positions
The average number of m6A sites in Nl-Nip group (79,925) was lower than that in Nip control group (83,011) (Figure 1f, Supporting Information: Table S2), and the dot-blot analysis of m6A levels in rice total mRNAs had negative correlation with BPH infestation, implying that m6A modification of rice genomic mRNA was repressed under BPH infestation (Figure 1g, Supporting Information: Figure S4). In addition, 42,062 specific m6A methylation positions were identified in Nl-Nip group, suggesting that 51.3% of positions appeared following BPH infestation (Supporting Information: Figure S5, Table S3). To examine whether there are conserved motifs in m6A genes, we compiled transcripts of all m6A genes from the four treatments (Supporting Information: Table S4). Four supreme conserved m6A modifications motifs were identified: GGACA (36.17%, 35.87%), GGACU (24.12%, 23.70%), GGACC (20.99%, 21.11%), and AGACU (18.72%, 19.32%), respectively, in Nip and Nl-Nip groups (Supporting Information: Figure S6). We defined the Nip and Nl-Nip consensus m6A methylation site as “RGACH” (R=A/G; H=A/U/C), which corresponds with the previously reported in rice and other plants (Parker et al., 2020).