ALKBH10B mediated epitranscriptomic regulation enhances drought tolerance of Arabidopsis thaliana via hormonal cross-talk and sustained photosynthesis

Epitranscriptomic N⁶-methyladenosine (m⁶A) mRNA modification has emerged as an important regulatory layer of gene expression and protein synthesis in plant stress adaptation. In this study, expression profiling revealed that drought stress induces a global reprogramming of the m ⁶ A machinery in Arabidopsis thaliana , with the m ⁶ A demethylase ALKBH10B being the most strongly up-regulated component. ALKBH10B transcription is induced by ABA, most likely via ABRE and MYB cis-elements, whereas jasmonate alleviates this activation. Moreover, ALKBH10B overexpressing plants (OX-1) accumulated wild type (WT) levels of ABA under drought stress but displayed a markedly reduced content in jasmonic acid (JA) and jasmonoyl-isoleucine (JA-Ile). They furthermore exhibit enhanced stomatal closure, improved water-use efficiency, and thus an enhanced drought tolerance. Transcriptome analysis revealed that drought stress induces fewer transcriptional changes in OX-1 plants compared to WT and the drought-sensitive alkbh10b-1 mutant. Differential expression and GO enrichment analyses highlight that photosynthesis-related processes were most affected by ALKBH10B activity, correlating with a preserved chlorophyll content and PSII efficiency in OX-1. Analysis by m⁶A-IP-qPCR showed that ALKBH10B directly demethylates specific photosynthesis-related and drought-responsive genes, thus promoting their sustained expression during stress. Other transcripts are indirectly regulated by ALKBH10B-dependent processes. Moreover, transcripts associated with respiration were enriched in OX‑1, indicating that ALKBH10B also supports mitochondrial energy metabolism during drought. Together, our results suggest that ALKBH10B enhances drought tolerance by coordinating m⁶A-dependent post-transcriptional regulation to maintain photosynthetic capacity and mitochondrial energy metabolism, as well as fine-tuning ABA-jasmonate crosstalk.