Impact of nickel on grapevine (Vitis vinifera L.) root plasma membrane, ROS generation, and cell viability

Abstract

-The present study investigated the impact of nickel (Ni 2+ ) on trans-membrane electrical potential (E M ) and permeability properties of plasma membrane (PM) in epidermal cells of adventitious grapevine roots. The relationship between disturbances of membrane functionality and the production of superoxide anion, hydrogen peroxide and cell viability after the exposure of roots to Ni 2+ was also studied. Treatments with 0.1-5 mmol L -1 NiCl 2 induced a concentration-dependent transient PM depolarization, which was recovered to the initial resting potential within 50-70 min in the presence of Ni 2+ . Longer (up to 24 h) exposure of roots to 1 mmol L -1 of Ni 2+ hyperpolarized the E M by approximately 17 mV. Application of the highest 5 mmol L -1 concentration of Ni 2+ during longer treatments (up to 48 h) resulted in the increase of membrane permeability; however the E M , cell viability, and superoxide content remained unaffected. The increase in the formation of hydrogen peroxide was time-and concentration-dependent and maximum production was recorded after 180 min of Ni 2+ treatment. We can conclude that oxidative stress resulting from an imbalance in the generation and/ or removal of hydrogen peroxide in the root tissues of grapevine was the major cause of Ni 2+ toxicity.

Micronutrient Status and Selected Physiological Parameters of Roots in Nickel-Exposed Sinapis alba L. Affected by Different Sulphur Levels

“…Of particular concern is the increasing area of Ni-contaminated agricultural soils together with rapidly rising Ni concentrations deposited in agricultural soils by airborne Ni particles. Moreover, the low soil pH as a result of reduced soil liming as well as acid rains may cause mobilization and enhance the solubility of Ni compounds [8,9]. It has been established that the Ni content in farm soils varies in a wide range from 3 to 1000 mg kg −1 DW.…”

“…It has been established that the Ni content in farm soils varies in a wide range from 3 to 1000 mg kg −1 DW. Most agricultural soils contain 25 mg kg −1 ; however, Ni content is very often raised, up to 26,000 mg kg −1 or even substantially higher, due to anthropogenic activities such as mining, smelting, burning of fossil fuels (coal and oil), use of industrial and municipal wastes (sewage sludge), as well as applications of pesticides and Ni-containing fertilizers, especially phosphates [8,9,10,11,12]. A strongly phytotoxic effect of high Ni concentrations manifests itself as growth and development inhibition including retarded germination, yield and quality reduction, as well as disturbances in photosynthesis, respiration, water relations, and sugar transport, which cause various ultrastructural modifications.…”