AGRICULTURAL BIOLOGY, 2016, V. 51, ¹ 1, pp. 89-99 ISSN 2412-0324 (English ed. Online) (SEL’SKOKHOZYAISTVENNAYA BIOLOGIYA) ISSN 0131-6397 (Russian ed. Print) ISSN 2313-4836 (Russian ed. Online) Plant tolerance — biochemical and physiological traits doi: 10.15389/agrobiology.2016.1.89rus doi: 10.15389/agrobiology.2016.1.89eng STUDY OF ISOZYME POLYMORPHISM IN SPRING BARLEY ( L.) CONTRASTING IN TOLERANCE TO LEAD A.V. DIKAREV, V.G. DIKAREV, S.A. GERAS’KIN, N.S. DIKAREVA Federal Agency of Scientific Organizations, 109 km, Kievskoe sh., Obninsk, Kaluzhskaya Province, 249032 Russia, e-mail dikarev.vlad@yandex.ru A b s t r a c t Lead is one of the most hazardous heavy metals (HM), for which the mechanisms of plant resistance is not completely clear. <...> One of the mechanisms for implementing toxic effect of lead is the generation of reactive oxygen species (ROS), which normally perform important regulatory function, but cause multiple violations of vital activity of cells at increased concentrations. <...> ROS level adjustment is carried out by antioxidant enzymes such as superoxide dismutase (SOD) and peroxidase (PER). <...> The effectiveness of most enzymes depends upon the existence of multiple isoforms, ensuring the most optimal operation under changing environment conditions. <...> As a working hypothesis, it has been suggested that the level of plant tolerance to the HM can be determined by differences in composition of izoforms of antioxidant enzymes differently contributeing to neutralization of the ROS excess. <...> To test this hypothesis the study of isoenzymatic spectra of superoxide dismutase and peroxidase enzyme systems and key enzyme of protein metabolism, the glutamate dehydrogenase (GDH), was carried out using embryos of germinating seeds of the spring barley ( L.) cultivars. <...> To analyze the composition of isoenzyme the germinating embryos of viable seeds were used with root length of 1 mm after 1 day germination. <...> Homogenized embryos of seeds were subjected to electrophoresis using 7.5 % polyacrylamide gel (PAGE) units with an alkaline buffer system (pH 8.9). <...> The analysis showed the presence of following isoenzymes from enzyme systems of superoxide dismutase, peroxidase and glutamate dehydrogenase: an obligate SODII, PERI and GDHI as well as rare SODI, SODIII + SODIV (always occurring together), SODV <...>