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<p><i>Fusarium graminearum</i>, the causal agent of Fusarium head blight (FHB), poses a major threat to global food security by contaminating cereals with the mycotoxin deoxynivalenol (DON). Although transcriptional and protein-level regulation of its stress response and virulence has been extensively studied, the functional significance of mRNA processing in these critical processes remains largely unexplored. Here, we identify Lsm8, a highly conserved core subunit of the nuclear Lsm2-8 complex, as a pivotal regulator linking RNA splicing fidelity to fungal growth, stress adaptation, and virulence. Deletion of <i>LSM8</i> disrupted Lsm2-8 assembly and nuclear localization, resulting in widespread intron retention in genes essential for stress signaling (<i>HOG1</i>, <i>ATF1</i>), development (<i>GPA1</i>, <i>STE12</i>), and trichothecene biosynthesis. Consequently, osmoadaptation was impaired, sexual reproduction was abolished, and both DON production and virulence were drastically reduced. We further demonstrate that intron-retained transcripts are predominantly degraded by the RNA exosome, revealing a conserved Lsm8–exosome module that maintains splicing fidelity and RNA surveillance. Given the deep evolutionary conservation of Lsm8 across eukaryotes, these findings uncover a fundamental post-transcriptional regulatory layer governing fungal stress response, virulence, and mycotoxin biosynthesis, and highlight RNA-processing factors as universal determinants of virulence and promising antifungal targets across eukaryotic pathogens.</p> Graphical Abstract <p></p>

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A conserved Lsm8–exosome module maintains RNA splicing fidelity to control fungal stress adaptation and virulence

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年2月10日

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  • Yiyi Ren,
  • Haolan Cheng,
  • Xingmin Han,
  • Meiling Guo,
  • Chenghui Xu,
  • Jiayue Yan,
  • Zhiwei Ge,
  • Zhonghua Ma,
  • Yun Chen

摘要

Fusarium graminearum, the causal agent of Fusarium head blight (FHB), poses a major threat to global food security by contaminating cereals with the mycotoxin deoxynivalenol (DON). Although transcriptional and protein-level regulation of its stress response and virulence has been extensively studied, the functional significance of mRNA processing in these critical processes remains largely unexplored. Here, we identify Lsm8, a highly conserved core subunit of the nuclear Lsm2-8 complex, as a pivotal regulator linking RNA splicing fidelity to fungal growth, stress adaptation, and virulence. Deletion of LSM8 disrupted Lsm2-8 assembly and nuclear localization, resulting in widespread intron retention in genes essential for stress signaling (HOG1, ATF1), development (GPA1, STE12), and trichothecene biosynthesis. Consequently, osmoadaptation was impaired, sexual reproduction was abolished, and both DON production and virulence were drastically reduced. We further demonstrate that intron-retained transcripts are predominantly degraded by the RNA exosome, revealing a conserved Lsm8–exosome module that maintains splicing fidelity and RNA surveillance. Given the deep evolutionary conservation of Lsm8 across eukaryotes, these findings uncover a fundamental post-transcriptional regulatory layer governing fungal stress response, virulence, and mycotoxin biosynthesis, and highlight RNA-processing factors as universal determinants of virulence and promising antifungal targets across eukaryotic pathogens.

Graphical Abstract