Transmission electron microscopy (TEM) in root of two treatments mentioned above (B.t; B.t + MIX) were fixed in 4% paraformaldehyde and 2% glutaraldehyde in 0.1 M Na-cacodylate buffer (pH 7.2) dehydrated in a graded series of ethanol and embedded in unicryl resin. Ultrathin sections were examined with a transmission electron microscope JEOL 1011.