Abstract
Sesame (Sesamum indicum L.) from the family of Pedaliaceae is one of the most ancient crops and oilseeds. It was a major oilseed crop in the ancient world due to its easiness of extraction, great stability, and resistance to drought. One of the most dangerous pathogens that affect sesame and other plants worldwide is phytoplasma. Phytoplasma can cause different character of symptoms such as: phyllody, the common symptom caused by phytoplasma infection, stunting, changing the color of leaves from green to yellow and alteration of the floral parts into leafy structures bearing no capsule and seeds, which consider a serious threat for the production of sesame in many countries. On the other hand, effect of the phytoplasma infection on plant enzymes such as Peroxidase and Polyphenol oxidase and hormones like Auxins, Cytokinin, Gibberellins and Abscisic acid were studied. Electron microscopy assay was used to verify the cellular changes which conducted as a result of phytoplasma infection. Infected sesame samples which examined by PCR were used as an exporter of phytoplasma and directly applied for electron microscopy test and the analysis of enzymes and hormones. Transmission electron microscopy (TEM) was used to detect ultra-structural changes in infected sesame plants.