The hairy root tissues exposed to 10 and 100 µM of MeJa were sampling after 72 h of incubation. All tissues were fixed by 3 hours in 1% glutaraldehyde, 4% formaldehyde in 50 mM sodium phosphate buffer, pH 7.2, and rinsed for 30 minutes with the same buffer. The fixed tissues were dehydrated in a graded series of 10%, 30%, 50%, 70%, 90% and 100% ethanol by 60 min each.
   The samples were mounted on a metallic grill (Polaron SEM coating system E S100) and sprayed with golden using 30 mA during 60s at 120 mTorr until a layer of 150 A. The samples were observed using a scan electronic microscope (GEOL JSM 6360 LV). The pictures were obtained by projecting the images to angles of +8° and -8° from the optical axis.