Abstract:Twenty-three isolates of gray leaf spot pathogen,Cercospora zeae-maydis,collected from growing area of Northern China were clustered based on their soluble protein and isozyme profiles obtained through native PAGE in order to base physiologically the pathogen differentiation at protein or isozyme level. A significant diversity of GLS pathogen was found in terms of spectrum change of soluble protein and isozyme including SOD, MDH, PPO, POD, EST and CAT among those strains, and the obvious difference in the numbers of bands and activities of bands with the same Rf value were also detected. Those data strongly supported that isozyme polymorphism could be indicators to reveal the pathogen diversity, however there was lack of evidence to show the correlation of isozyme spectrum with pathogen collection location, therefore at least based those enzymes mentioned above, the change of isozymes was unable to represent the difference of pathogen adaptability to environment. The phenomenon was possibly associated with the wider adaptability of the pathogen to environments or other physiological factors probably involved in the regulation of pathogen adaptability.