Protoplasting and fluorescence-activated cell sorting
(FACS)
Protoplasting and sorting were performed according to the methodology described by Birnbaum et al. (2005) using the enzyme mix
described by Yadav et al. (2009). Approximately 250 seedling roots
were harvested within 5 min, sliced and placed in protoplasting
solution for 1 h. Between 1000 and 25 000 protoplasts were sorted into 350 ll of reverse transcriptase (RT) buffer (RNA Easy kit; Qiagen, http://www.qiagen.com) within 10 min, and flash frozen.