Phytoplasma are phloem-restricted plant pathogenic bacteria that cause hundreds of diseases. They are not cultivated in vitro and can be transmitted through insect vectors or grafting. Researches have been investigating defense pathways to different pathogens (bacteria, fungi...) but little is known about defense pathways activated in phytoplasma infected plants. In this study, the expression of genes related to salicylic acid (SA), ethylene (ET) and jasmonic acid (JA) pathways have been investigated in stolbur C phytoplasma and stolbur PO phytoplasma-infected tomato. We noted elevated level of expression for Pathogenesis Related (PR) genes. Transcription of SA and ET marker genes was up-regulated in stolbur PO and stolbur C-infected tomato, while transcription of PIN2, a gene regulated by JA, increased only in stolbur C-infected tomato.