Dissolved organic matter in water of Daugava river

The Influence Of High Temperature On Oxidative Processes andAccelerated Senescence in Wheat Seedling (Triticum aestivum L.) ColeoptileM.Savicka* 1 , N.Škute 11 Institute of Ecology, Daugavpils University, Daugavpils, Latviae-mail: marina.savicka@du.lvMost environmental stresses are affecting on the production of active oxygen species inplants, causing oxidative stress. Temperature, along with light, humidity, etc., belongs tothe important factors in the environment of plants. It is also a tool for research, for inmany cases the processes of growth can be differentiated by their temperature responses.Heat shock is a form of the oxidative stress, resulting in the formation of many toxic ROSin plants (Tsang et al. 1991; Bhattacharjee, Mukherjee, 2003). High temperature inducedoxidative stress led to accelerated senescence of plants. Therefore, the objective of thiswork was to study the response of coleoptile of wheat seedlings to elevated temperatures.The present study investigated the effect of heat stress on different stages of growth inwheat (Triticum aestivum L.). The behaviour of wheat seedling coleoptile was studied,particularly at the physiological level. High temperature is known to induce oxidativeinjury in plants by inducing production of active oxygen species. Active oxygen species,cause lipid peroxidation (LP) and consequently membrane injury. High-temperature (15,30 and 60 min and 24h at 42°C) influence on senescent organ of wheat seedlings(Triticum aestivum L.) was analyzed taking into consideration the changes in somechanges on the molecular level, such as content of LP products (malodialdehyde (MDA)and conjugated dienes (CD)) and membrane permeability. The effect of high temperaturewas analyzed at the early stages (4 day-old) and at the late stages (7 day-old) of seedlingdevelopment. LP level was directly correlated with temperature, exposure time, and theirinteraction. Long-term high-temperature exposure (24h at 42°C) significantly increasedLP (MDA and CD content) in coleoptile of wheat seedlings at 4 and 7d of seedlingdevelopment. However, the increase in LP products was observed only at the late stagesof seedling development after short-term high temperature exposure. Heat shock causedan increase in the electric conductivity of cell membrane, which led to the loss ofmembrane selective permeability.1. Tsang, E.W.T., Bowler, C., Hérouart, D., Van Camp, W., Villarroel, R., Genetello, C. Differentialregulation of superoxide dismutases in plants exposed to environmental stress. Plant Cell. 1991, 3:783–792.2. Bhattacharjee, S., Mukherjee, A.K. Implications of reactive oxygen species in heat shock inducedgermination and early growth impairment in Amaranthus lividus L. Biologia Plantarum. 2003, 47(4): 517-522.- 20 -