Antimicrobial Activity of Vanadium and Germanium Nanoaquacitrates in vitro and their Physiological Effect on Wheat Plants in vivo
Authors:   Zabolotny Institute of Microbiology and Virology, NAS of Ukraine, Huliaieva H.B. , Tokovenko I.P. ,   Zabolotny Institute of Microbiology and Virology, NAS of Ukraine, Pasichnyk L.A. ,   Zabolotny Institute of Microbiology and Virology, NAS of Ukraine, Patyka V.P. ,   Zabolotny Institute of Microbiology and Virology, NAS of Ukraine, Bohdan M.M. ,   Zabolotny Institute of Microbiology and Virology, NAS of Ukraine, Kharchuk M.S. ,   Zabolotny Institute of Microbiology and Virology, NAS of Ukraine, Maksin V.I. ,   National University of Life and Environmental Sciences of Ukraine, Patyka M.V. ,   National University of Life and Environmental Sciences of Ukraine, Kaplunenko V.G. ,   National University of Life and Environmental Sciences of Ukraine
Published: December 2020

Phytopathogenic bacteria and phytoplasmas, in particular Pseudomonas syringae pv. atrofaciens and Acholeplasma laidlawii var. granulum are causative agents of cereal crops diseases. Nanoparticles and biologically active compounds created with the use of nanotechnologies are considered as alternative modern measures to control phytopathogenic microorganisms. Antimicrobial activity is already established for gold, silver, copper, magnesium, iron, zinc, aluminum, cerium, titanium, cadmium, nickel and vanadium. At the same time, antimicrobial activity of germanium and its citrates as well as citrates of others nanoparticles, including vanadium, are studied insufficiently. The physiological effect of vanadium and germanium nanoaquacitrates on wheat plants in vivo, both on state and photochemical activity of the photosynthetic apparatus and activity of superoxide dismutase of plant tissue are poorly known too. Aim. The aim of our work was to study the antimicrobial activity of vanadium and germanium nanoaquacitrates in vitro and their physiological influence on wheat plants in vivo. Methods. A. laidlawii var. granulum 118 (UCM BM-34) was cultured in the liquid nutrient medium CM IMV-72 (pH=7.8) in thermostat at 320 C for 72 hours. P. syringae pv. atrofaciens D13 was cultured on potato agar in thermostat at 26–280°C. For artificial infection a bacterial suspension with a density of 1×109 CFU/ml according to the turbidity standard was prepared. Nanoaquacitrates of V (30 mg/dm3) and Ge (5 mg/dm3) were used in our study. After a short-term (15 minutes) action of the test compounds, morphological features of A. laidlawii var. granulum and P. syringae pv. atrofaciens were studied using a transmission electron microscope (TEM) JEOL JSM 1400 (Zabolotny IMV NASU). The plants of wheat of Pecheryanka variety were grown in field condition on 50 m2 area plot. Pre-sowing treatment of spring wheat seeds before sowing was carried out with solutions of V (30 mg/dm3) and Ge (5 mg/dm3) nanoaquacitrates according to the experimental scheme. The experiment was carried out in three repetitions. In addition, biological preparation (B.P.) Extrakon, which consists from natural consortium of beneficial microorganisms inoculated into a peat-like substrate, was applied into the soil before sowing. Artificial inoculation by phytoplasma A. laidlawii var. granulum 118 was performed using Clement`s method (subepidermal injection into the stem) in the tillering phase of wheat plants growth. Artificial infection of wheat plants with P. syringae pv. atrofaciens D13 was performed by injecting a bacterial suspension into the stem in the booting phase of plants growth. The activity of superoxide dismutase (SOD) was determined by the ability of the enzyme to inhibit the photochemical reduction of nitro blue tetrazolium. Changes in the following fluorescent parameters were analyzed: Fv/Fp and Rfd. For statistical processing of data, calculations of the arithmetic mean and its standard error were performed. Results. It was shown using electron microscopy that contact of Ge and V nanoaquacitrates with P. syringae pv. atrofaciens D13 and A. laidlawii var. granulum 118 resulted in cytomorphological changes of cells, homeostatic disruption and death. It was found in the field studies that SOD activity level increased in the tissues of wheat leaves to different values in plants infected with phytopathogenic microorganisms without any treatment and in cases of pre-sowing treatment with Ge and V nanoaquacitrates and B.P. Extrakon. Field investigations showed that combined use of consortium of soil microorganisms (B.P. Extrakon) and pre-sowing treatment of wheat seeds with V and Ge nanoaquacitrates decreased negative impact of infection caused by A. laidlawii var. granulum 118 and P. syringae pv. atrofaciens D13 on the state and photochemical activity of the photosynthetic apparatus of Triticum aestivum: the level of quantum efficiency of photosystem II (PSII) and the assimilation activity coefficient Rfd increased. This effect of studied biologically active substances is due to both antimicrobial action and activation of the antioxidant defense system of plant cells. Conclusions. It was shown in our investigations that SOD activity increased in leaf tissues after application of biologically active agents in the next order: pre-sowing treatment with Ge nanoaquacitrates < pre-sowing treatment with V nanoaquacitrates < biological product (B.P.) Extrakon + pre-treatment with Ge nanoaquacitrates < B.P. Extrakon + pre-sowing treatment with V nanoaquacitrates. A significant increase of SOD activity of wheat leaves (in the tubing phase) was noticed at both types of infection – caused by phytopathogenic bacteria and phytoplasma, especially for the last one. A significant increase in the surface area of assimilation apparatus of wheat plants (in the tillering phase) in cases of wheat seeds pre-sowing treatment with Ge and V nanoaquacitrates before planting was observed. Pre-sowing treatment of wheat seeds with Ge and V nanoaquacitrates in combination with B.P. Extrakon use on wheat plants infected with A. laidlawii var. granulum and P. syringae pv. atrofaciens improved photosynthesis and status of photosynthetic apparatus of plants.