StALKBH10B-Mediated RNA m6A Modification Inhibits Potato Salt Tolerance by Targeting Flavonoids and ABA Signalling Pathways

Abstract

N⁶-methyladenosine (m⁶A) is the most prevalent methylation modification present in mRNAs, which has been confirmed to participate in many developmental and biological processes. However, the biological function and specific regulatory mechanism of m⁶A modification in relation to salt tolerance of potato remain obscure. Here, we generated a transcriptome-wide m⁶A map using salt-resistant and salt-sensitive potato varieties under salt stress conditions to uncover patterns of m⁶A methylation in the potato response to salt stress. MeRIP-seq revealed that m⁶A is significantly enriched in the CDS region in potato, by recognising the conserved motifs including RRACH and URRUAY. Numerous differential m⁶A-deposited transcripts have been identified, which were significantly enriched in ABA-signalling and flavonoids biosynthesis pathway in two potato varieties after salt stress. Notably, a positive correlation was observed between the m⁶A enrichment and mRNA abundance based on combined analysis of MeRIP-seq and mRNA-seq. StALKBH10B was identified as an m⁶A demethylase for decreasing m⁶A modification levels, inhibiting mRNA stability and translation efficiency of ABA signal-related genes (StABF3, StAAO3, and StZEP7) and flavonoids biosynthesis genes (StPAL3, StCHS, and StFLS), and overexpression of StALKBH10B suppressed salt resistance in potato. Collectively, we uncover a novel mechanism of post-transcriptional modification involved in affecting salt stress response in potato, via StALKBH10B-mediated m⁶A demethylation on targeted transcripts in the ABA signalling and flavonoids biosynthesis pathway, thereby providing candidate genes for the breeding of stress-tolerant potato cultivars.