Dynamics in the activity of peroxidase and its isoforms in leaves of different apple cultivars

Background. Various approaches are used for identification of the most resistant fruit crop cultivars, including the analysis of different physiological and biochemical indicators. In Krasnodar Territory, Russia, one of the major stressors in summer is the hydrothermal stress. Drought and heat lead to an oxidative stress, as reactive oxygen species are produced in plant cells. Plants respond to oxidative damage by activating antioxidant enzymes, such as superoxide dismutase, catalase, and various peroxidases. Peroxidase is able to decompose hydrogen peroxide. Peroxidase activity was calculated under natural summertime changes in the hydrothermal pattern (control) and in simulated high-temperature conditions.Materials and methods. Three apple cultivars of Russian breeding, ‘Fortuna’, ‘Soyuz’ and ‘Prikubanskoe’, and cv. ‘Ligol’ of Polish origin were studied. In the summers of 2018–2019, their leaf samples were analyzed to assess peroxidase activity and its isozyme composition under control and stress conditions. Native electrophoresis in polyacrylamide gel was used for separation of peroxidase isoforms. Malondialdehyde content was measured to identify oxidative stress levels in apple leaves.Results. The tested indicators demonstrated a high degree of heterogeneity induced by both cultivar specificity and seasonal weather dynamics. Peroxidase isoforms with a molecular weight of 70 to 60 kDa, characterized by the maximum level of variability (1–4 isoforms), were isolated. Two other groups included 1–3 isoforms with a molecular weight of ~130–100 kDa, and one with a molecular weight of ~55 kDa. The highest enzyme activity was found in cvs. ‘Fortuna’ and ‘Soyuz’ in July 2018, the hottest month during the period of research. Under simulated conditions, the triploid cultivar ‘Soyuz’ was least susceptible to the stress impact.

Esterase and peroxidase isoforms during initial stages of somatic embryogenesis in Fritillaria meleagris L. leaf base

The aim of this study was to determine the enzymatic profile of esterases and peroxidases during early stages of somatic embryogenesis of Fritillaria meleagris L. Somatic embryogenesis was induced using the leaf base as explant on a medium supplemented with 2,4-dichlorophenoxyacetic acid (2,4-D). Zymography showed the presence of different moieties, six isoforms of esterases and peroxidases, during morphogenesis as compared to control explants. One isoform of esterases was detected only during the process of somatic embryogenesis, and one isoform was detected in control explants. Analysis of esterases with 1-naphthyl butyrate proved that esterases, which participate in somatic embryogenesis of F. meleagris, belong to the family of aryl esterases. For the first time it was proved that five isoforms of esterases, which are involved in morphogenesis of F. meleagris, belong to the family of aryl esterases, while two isoforms are carboxyl esterases. One isoform of carboxyl esterases was visible in control explants. This is also the first description of peroxidases during the morphogenetic process, and of the difference between aryl and carboxyl esterases. More isoforms of esterases during morphogenesis as compared to control explants are probably responsible for some early physiological process during somatic embryogenesis of F. meleagris.

Production of Ligninolytic Enzymes by Cultures of White Rot Fungi

Some Basidiomycota were chosen for studies of key ligninases synthesis (25°C, 30 days) in modified medium (shaken or not cultures) with added wheat straw. Liquid Czapek medium with straw yielded a higher amount of laccase than peroxidase, ground straw induced enzyme worse than chopped straw. With peroxidase the reverse dependencies were observed. Laccase of Lentinus edodes synthesized two enzyme isoforms (ca 30 and 16 kDa). In T. versicolor culture active laccase protein with highest molecular mass ca 65 kDa was found. P. sajor-caju yielded three different peroxidase isoforms. Ligninase biosynthesis depended on strain, straw fragmentation extent, culture method and growth medium.