Compared to direct exposure to heat shock (HS), plants exhibit an increased survival rate to heat stress when they have previously acclimated through exposure to sub-lethal heat conditions (ACC). The mechanism underlying it is referred to heat memory, manifested as a more effective transcriptional response of heat-tolerance related genes. The active transcriptional state is associated with the maintenance of epigenetic mark at specific genomic loci. However, it remains unclear whether the maintenance of active state in localized regions involves rearrangement of chromatin organization during the heat memory phase. Here, our objective is to elucidate how chromatin organization functions in Arabidopsis thaliana to withstand recurring heat environment.
We selected various knockout mutants affecting chromatin organization in Arabidopsis thaliana and subjected them with the wild type to ACC (37°C) and subsequent HS (43.5°C) treatments. Compared to the wild type, the mutant groups exhibited reduced survival rates and decreased fresh weight 7 days post-treatment, indicating diminished heat memory ability. Interestingly, in the RNA-seq data, the expression level of HEAT SHOCK TRANSCRIPTION FACTOR A2 (HSFA2), crucial for heat memory maintenance, was higher in one of the mutant groups compared to the wild type at the one-hour time point after ACC+HS treatment. Additionally, we analyzed gene expression differences in the RNA-seq data between the ACC+HS and HS-only treatment groups in the mutants. Now, we are trying to further investigate whether the differentially expressed genes are involved in chromatin dynamics through micro-C analysis and live-cell imaging of specific gene loci.