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 Overall design: 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

应激颗粒（Stress granules, SGs）是一类细胞质结构，可在不利环境条件刺激下形成。目前学界对调控转录本在应激颗粒中富集的分子机制仍知之甚少。尽管m6A（N6-甲基腺嘌呤）在植物转录组调控中的作用已得到公认，但其对应激颗粒组成与组装的影响仍不甚明晰。
在狭叶羽扇豆（Lupinus angustifolius, L. angustifolius）中，应激颗粒呈现独特的双区域结构：由环状结构与中央区域组成，二者在超微结构与组成成分上均存在差异。
完成转录组分析后，研究人员选取特定mRNA，以探究其在应激颗粒中的定位情况并检测其m6A修饰水平。
低氧应答基因（ADH1与HUP7）的转录本m6A水平显著低于持家基因（housekeeping genes），但仅ADH1未在应激颗粒中被检测到。HUP7 mRNA的m6A修饰水平较低，可同时存在于应激颗粒与细胞质中，这可能与其极高的表达量有关。
仅在应激颗粒的组装过程中可检测到高水平的m6A修饰。
在m6A水平降低的拟南芥（Arabidopsis thaliana, A. thaliana）突变体中，ECT2未在应激颗粒中被检测到，且poly(A) RNA水平与应激颗粒的数量均略有下降。
综上，本研究结果表明m6A修饰对应激颗粒组装的影响较为有限。但m6A修饰与细胞质总转录本数量之间的相互作用，似乎可调控mRNA的分区分布与应激颗粒的组装过程。
整体实验设计：对在生理条件、15小时淹水条件、15小时淹水后复水6小时条件下生长的狭叶羽扇豆根部进行RNA测序，以此开展基因表达谱分析。