Interplay between m6A modification and transcripts quantity: Impacts on mRNA composition in plant stress granules

Stress granules (SGs) are cytoplasmic structures that emerge in response to unfavorable environmental conditions. The mechanisms governing the accumulation of transcripts in SGs are only partially understood. Despite the recognized role of m6A in plant transcriptome regulation, its impact on SGs' composition and assembly remains elusive. In L. angustifolius, SGs display a distinctive bi-zonal structure comprising of a ring and a central area with differences in ultrastructure and composition. Subsequent to the transcriptome analysis, specific mRNA were chosen for investigating their localization within SGs and assessing m6A levels. Transcripts of hypoxia-responsive genes (ADH1 and HUP7) showed significantly lower levels of m6A compared to housekeeping genes, but only ADH1 was absent in SGs. HUP7 mRNA, characterized by a low quantity of m6A, is present both in the SGs and cytoplasm, probably due to extremely high expression level. The high amount of m6A was observed only during the assembly of SGs. In mutants of A. thaliana with reduced levels of m6A, ECT2 was not observed in SGs, and poly(A) RNA levels and the number of SGs were slightly reduced. In summary, our findings demonstrate a limited impact of m6A modification on SGs assembly. However, the interplay between m6A modification and the overall transcript quantity in the cytoplasm appears to play a regulatory role in mRNA partitioning and assembly of SGs Gene expression profiling analysis using data obtained from RNA-seq of narrow-leafed lupin (L.angustifolius) roots grown under physiological conditions, 15-hour submergence, 15 hour submergence followed by 6 hour reoxygenation