Salicylic acid-induced gene expression in wild-type Col-0 and mutant ube4 Arabidopsis thaliana plants

Activation of plant immunity is associated with dramatic transcriptome reprogramming to prioritise immune responses over normal cellular functions. Changes in gene expression are coordinated by the immune hormone salicylic acid (SA). Here we investigated the involvement of the E4 ubiquitin ligase UBE4/MUSE3 in SA-induced transcriptional reprogramming. We show that loss of UBE4 function results in amplified expression of SA-induced, NPR1-dependent gene expression. Twelve-day old Arabidopsis thaliana seedlings of wild-type Col-0, mutant ube4 (SAIL_713_A12) and mutant npr1-1 genotypes were grown on MS media supplemented with 1X Gamborg vitamins in an environmental chamber with 16/8 hour day/night light regime (120 mol m-2 s-1 light intensity) and 22 degrees Celcius. Seedlings were then transferred to 6-well plates and immersed in 10 ml of 0.5 mM SA or water. After 12 hours seedlings were harvested and for each treatment ~50 seedlings were pooled together into a single biological repeat. In total two independent biological repeats were collected. After harvesting seedlings were briefly dried on tissue and immediately frozen in liquid nitrogen until further analysis.