Tag Archives: NADPH-oxidase

Induction of plant cells heat resistance by hydrogen sulfide donor is mediated by H(2)O(2) generation with participation of NADPH oxidase and superoxide dismutase

Yu. E. Kolupaev1,2, E. N. Firsova1, Т. О. Yastreb1

1V.V. Dokuchaev Kharkiv National Agrarian University, Ukraine;
e-mail: plant_biology@ukr.net;
2V.N. Karazin Kharkiv National University, Ukraine

The participation of enzymatic systems carrying out generation and conversion of reactive oxygen species (ROS), in realization of the stress-protective effect of hydrogen sulfide (H2S) on wheat coleoptile cells was investigated. It has been shown that the treatment of isolated coleoptiles with a 100 μM hydrogen sulfide donor sodium hydrosulfide (NaHS) caused a transient enhancement of the generation of superoxide anion radical (O2•–), an increase of hydrogen peroxide content and superoxide dismutase (SOD) activity in them. The increase in ROS generation was eliminated by the inhibitor of NADPH oxidase imidazole, but not by the peroxidase inhibitor sodium azide. Treatment of coleoptiles with SOD inhibitor sodium diethyldithiocarbamate (DDC) enhanced the generation of O2•– and neutralized the effect of increasing H2O2 content induced by NaHS. One day after treatment with the H2S donor, the generation of ROS decreased to a control level, while the activity of antioxidant enzymes increased markedly and the resistance of coleoptiles to damaging heating­ was increased. These effects of the hydrogen sulfide donor were eliminated by coleoptiles’ treatment with inhibitors of NADPH oxidase (imidazole) and SOD (DDC). It was concluded that both NADPH oxidase, genera­ting O2•– , and SOD, which turns it into H2O2 performing signaling functions, are involved in the formation of a signal that induces protective systems and causes an increase in heat resistance of plant cells.

Participation of the active oxygen forms in the induction of ascorbate peroxidase and guaiacol peroxidase under heat hardening of wheat seedlings

Yu. E. Kolupaev, O. I. Oboznyi

V. V. Dokuchayev Kharkiv National Agrarian University, Ukraine;
e-mail: plant_biology@mail.ru

The influence of one-minute hardening heating at 42 °C on the dynamics of hydrogen peroxide generation and activity of antioxidant enzymes in roots of winter wheat seedlings has been investigated. It was shown that the content of hydrogen peroxide increased within the first 30 minutes after heat influence, whereupon it approached the level of control variant. The activity of superoxide dismutase (SOD) increased significantly within 10 min after heating and was maintained at a high level during 24 hours of observation. The activi­ty of ascorbate peroxidase and guaiacol peroxidase increased after 3-6 hours after the hardening and reached its maximum after 24 hours, when there was the most significant increase in heat resistance of seedlings. The short-term increase in hydrogen peroxide content caused by hardening heating was suppressed by treatment of seedlings with H2O2 scavenger dimethylthiourea, inhibitors of NADPH-oxidase (imidazole) and SOD (sodium diethyldithiocarbamate). All these effectors levelled the increase of activity of ascorbate peroxidase and guaiacol peroxidase and significantly inhibited the development of heat resistance of seedlings. The conclusion was made about the role of hydrogen peroxide produced with the participation of NADPH­-oxidase and SOD in the induction of antioxidant system by heat harde­ning of wheat seedlings.

Reactive oxygen forms and Ca ions as possible intermediaries under the induction of heat resistance of plant cells by jasmonic acid

Yu. V. Karpets, Yu. E. Kolupaev, T. O. Yastreb, O. I. Oboznyi,
M. V. Shvydenko, G. A. Lugova, A. O. Vayner

Dokuchayev Kharkiv National Agrarian University, Ukraine;
e-mail: plant_biology@mail.ru

The participation of reactive oxygen species (ROS) and calcium ions in realization of influen­ce of exogenous jasmonic acid (JA) on the heat resistance of wheat coleoptiles has been investigated­. Influence of 1 µM JA caused the transitional intensifying of generation of superoxide anion-radi­cal (O2•–) and hydrogen peroxide in coleoptiles with the maximum within 15-30 minutes after the treatment beginning. Within the first hour after the beginning of coleoptiles treatment with JA the increase of superoxide dismutase (SOD) activi­ty was noted. Later on (within 5-24 hours after the treatment beginning) there was the lowering of ROS generation by coleoptiles of experimental variant, and the SOD activity approached the control value. Intensifying of generation of superoxi­de radical induced by JA was suppressed by the antioxidant ionol and was partially levelled by imidazole (inhibitor of NADPH-oxidase), EGTA (chelator of extracellular calcium) and lanthanum chloride (calcium channels blocker). Pretreatment of coleoptiles with the ionol, imidazole, EGTA and LaCl3 also partially removed the effect of increase of their resistance to the damaging heating caused by exogenous JA. It is supposed that the ROS gene­rated with participation NADPH-oxidase, which activity depends on the receipt of calcium ions from extracellular space in the cytosol, are involved in realization of physio­logical effects of JA.