Laser Capture Microdissection
LCM processing were performed as described previously (Chen et al., 2019; Zhou et al., 2018). The SC and non-SC regions in cortex, phloem, xylem and pith were dissected using the Laser Capture Microdissection System (Leica Microsystems, Germany). Laser conditions for microdissection were set as: aperture set at 37, power of 60 μJ, speed at 11, head current of 100% and pluse frequency of 3309 Hz. An area of approximately 1 mm2 (~6-10 SCs or non-SCs) of certain regions were dissected separately for each sample. The microdissected tissues were collected into caps of 500 µL microcentrifuge tubes (Leica Microsystems) by gravity and stored temporarily at -20 ℃ prior to extraction. We captured 6 replicated samples for each type of SC and non-SC regions of different ARs.