STABILIZED1 as a heat stress-specific splicing factor in Arabidopsis thaliana.

To overcome high temperature stress, plants have developed transcriptional cascades which express a large amount of chaperone proteins called heat shock proteins (HSPs). In our recent publication, we reported that STABILIZED1, as an U5-snRNP-interacting protein, is involved in the splicing of heat shock factor (HSF) and HSP transcripts during high temperature stress. This indicates that not only transcriptional regulation, but also post-transcriptional regulation by STA1, is essential for the full activation of HSF-HSP cascades and for thermotolerance. Here, we observed that the splicing of HSP transcripts was induced independent of STA1 at room temperature after heat acclimation, indicating that STA1 acts as a high temperature-specific splicing factor for the splicing of HSP transcripts. Our findings suggest the molecular mechanism for how HSF and HSP transcripts are spliced well under high temperature stress that blocks the splicing of overall transcripts.