5 6 dichloro 1 beta d ribofuranosylbenzimidazole drb

The spt6l heterozygous seeds (SALK_016621), previously described (14 (link)), were obtained from the Arabidopsis Biological Resource Center (ABRC) at Ohio State University. Three formerly generated transgenic lines: ProREF6:REF6-GFP (16 (link)), ProACC1:ACC1-GFP (17 (link)) and 35S:GFP (16 (link)) were used. All Arabidopsis seeds used were in the Columbia (Col-0) background. Plants were grown either on half-strength Murashige and Skoog ( MS) medium (0.5× MS salts, 1.5% [w/v] sucrose, and 0.8% agar [pH 5.8]) or in soil under 16 h/8 h light/dark cycle at 23 °C. For the inhibitor treatment, 5,6-dichloro-1-beta-d-ribofuranosylbenzimidazole (DRB) (10010302, Cayman Chemical), flavopiridol (10009197, Cayman Chemical), or triptolide (11973, Cayman Chemical) was added to the media at a final concentration of 100, 10 and 10 μM, respectively. For the short-time treatment, 10-day-old seedlings were sprayed with 10 μM flavopiridol and grown on MS plates for 1 h. For the heat shock treatment, seeds were germinated and grown on MS plates for 7 days at 23 °C. The plates were moved to 17 °C for 3 days, after which time, the seedlings were subjected to a heat shock treatment for 1 h at 27 °C. The primers used for genotyping are listed in Supplementary Table S1.