Interplay between stress granule-like structures and nuclear RNA export in a heat shock-specific manner

When stress strikes, cells initiate adaptive responses, including perturbation of RNA splicing, modulation of nuclear RNA export, and formation of stress granules (SGs). Despite their central role, the composition and regulation of fungal SGs remain poorly understood. Here, we report the formation of heat shock-induced SG-like structures in Fusarium graminearum. Through purification of SG-like structures followed by RNA-sequencing, we performed a transcriptome-wide characterization of their associated transcripts and found that heat shock induces a distinct enrichment of intron-containing transcripts within SG-like structures compared to physiological conditions. Moreover, these SG-like structures co-localize with the nuclear RNA export factor FgYra1 in the nucleus, linking SG-like structures to the RNA export system. Furthermore, transcripts associated with SG-like structures exhibit distinct nuclear retention behaviors during heat shock, and the loss of FgYRA1 alters nuclear retention in an atypical manner. Together, this study defines the molecular architecture of F. graminearum SG-like structures and highlights their functional relevance in coordinating nuclear RNA export during heat shock.