In order to elucidate the enzyme mechanism of starch biosynthesis in wheat endosperm and provide theoretical basis to enhancing wheat yield,we identified the isozyme forms,organ localization and subunits constitution of AGP in nine wheat cultivars from different provenances by using native polyacrylamide gel electrophoresis (Native-PAGE) and SDS polyacrylamide gel electrophoresis (SDS-PAGE).Results of the present study showed that:(1)There are six AGP isozymes in wheat,ie,AGPp,AGPs,AGPe1,AGPe2,AGPe3 and AGPe4.(2)AGPs localized in leaf and seed coat of wheat,but AGPp was solely in seed coat.AGPe1,AGPe2,AGPe3 and AGPe4 were exclusively present in wheat endosperm.AGPe1 expressed first,following by the AGPe2 and AGPe3.The AGPe4 expressed last.(3)Every AGP isozyme of endosperm was all composed of both large and small subunits.The molecular size of large and small one were approximately 51~54 kD and 50 kD,respectively.(4)Spatial localization of the AGP isozymes manifests organ specificity.AGP isozymes of endosperm exhibit rich genetic polymorphism,and expresse according to different developing periods of grain.AGPe3,AGPe1 and AGPe2 could be the key isozymes of AGP,and be a very important determinant for total AGP activity,play an major role in starch biosynthesis in late filling period of wheat grain.