Transcriptomic analysis of heat stress transcriptional memory in Arabidopsis seedling

Plants can be primed by a stress cue to mount a faster and stronger activation of defense mechanisms upon a subsequent stress. A crucial component of such stress priming is the modified reactivation of genes upon recurring stress, a phenomenon known as transcriptional memory. The transcriptional memory in response to heat stress is not clear at the genome scale. We used microarrays to identify genes that showed transcriptional memory in response to recurring heat stress. Arabidopsis thaliana 7-d-old wild-type (Col-0) seedlings subjected to four different treatments were collected for RNA extraction. Naïve: 7-d-old seedlings kept at normal growth condition without heat stress; Primed: 4-d-old seedlings were treated at 37 °C for 1 h then at normal growth condition for 3 d before sample collection; Triggered: 7-d-old seedlings were treated at 37 °C for 1 h before sample collection; Primed and triggered: 4-d-old seedlings were treated at 37 °C for 1 h, transferred to normal growth condition for 3 d, treated at 37 °C for 1 h again before sample collection. The heat treatment was performed around 10 am of the day. For HSFA2 knockout mutant (SALK_008978), the same treatments were conducted except the primed. The experiment contained at least two biological replicates for each treatment.