Seed surface sterilization
Seeds of Arabidopsis and Artemisia were surface sterilized as previously described by (van de Mortel et al. 2012). Briefly, the seeds were placed in opened Eppendorf tubes inside a desiccator with two 100-mL beakers each containing 50 mL sodium hypochlorite (12% v/v). To each of the beakers, 1.5 mL concentrated HCl was added and the seeds were exposed for three hours to the chlorine gas generated inside the desiccator. Seeds of Brassica olearacea var. italica, cultivar Coronado were surface sterilized for 30 min in 1% (v/v) sodium hypochlorite supplemented with 0.1 % (v/v) Tween 20 and then washed three times with ample sterile distilled water.