Abstract: To identify the changes of proteins related to Paulownia witches′ broom (PaWB) disease occurring, isobaric tags for relative and absolute quantitation (iTRAQ) technique was employed to analyze the changes of proteins abundance among healthy Paulownia tomentosa seedlings, phytoplasma-infected seedlings, and the ones treated with 20 or 60 mg/L methyl methane sulfonate (MMS).The results indicates that a total of 1 622 proteins were identified, of which, 35 differentially abundant proteins were considered to be closely associated with PaWB disease.Among them, the expression of chloroplast sedoheptulose-1, 7-bisphosphatase (SBPase), plasma membrane ATPase, and photosystemⅡ10 kDa polypeptide were significantly differentially abundant.These proteins are mainly involved in carbon fixation in photosynthetic organisms, photosynthesis and oxidative phosphorylation.