Biochemical changes induced by phytoplasmas in plants

Phytoplasmas are cell wall-less and pleomorphic bacterial pathogens that cause considerable yield losses in more than 1000 plant species worldwide and transmitted by sap-feeding insects. Phytoplasma-infected plants exhibit symptoms including witches’ broom, phyllody, virescence, yellowing induced by the phytoplasma effector proteins. It has been revealed that phytoplasmas are capable of modulating biochemical responses of plants involved in defense mechanisms. In this respect, phenolic compounds, free amino acids in source leaves, protein contents, some secondary metabolites, and polyamines were found to increase, while chlorophyll content and photosynthetic activity and the number of chemical compounds were reduced as a consequence of phytoplasma infection. Therefore, the objective of this study was to review the chemical composition changes in phytoplasma-infected plants.