Changes of microsomal membrane properties in spring wheat leaves (Triticum aestivum L.) exposed to enhanced ultraviolet-B radiation.
The properties of microsomal membranes in spring wheat leaves (Triticum aestivum L. cv. Ganlong No. 92-005) exposed to (0) control, 8.64 (T1) and 11.2 kJ m(-2) day(-1) (T2) biologically effective UV-B irradiation (UV-B(BE)) were studied under greenhouse conditions. These irradiance levels correspond to a decrease in the stratospheric ozone of approximately 12.5 and 20%, respectively, for a clear solstice day at Lanzhou (36.04 degrees N, 1550 m), China. Compared with controls, the content of malondialdehyde (MDA) increased by 70.8% in T1 and 83.8% in T2 on the 7th day of the radiation, and the IUFA (index of unsaturated fatty acids) decreased, indicating peroxidation of lipid acids. Simultaneously, a drastic decrease of phospholipid content after 21 days and an increase of membrane lipid microviscosity on UV-B irradiation were also found, suggesting a reduction in the fluidity of membrane lipids. Ethylene emission by the microsomal membrane, in the presence of exogenous 1-aminocyclopropane-1-carboxylic acid was higher in the wheat seedlings after 7, 14 and 21 days' irradiation than in the controls. These changes were correlated with a rise in lipoxygenase activity. Membrane-bound enzymes (Ca2+ -ATPase and Mg2+ -ATPase) were promoted by UV radiation in the first 7 days and significantly decreased after 14 and 21 days' treatment in comparison to control. Our results suggest that UV-B radiation may cause changes in structural complexity and function of microsomal membranes in spring wheat leaves.
An
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School of Life Science, State Key Laboratory of Arid Agrioecology, Lanzhou University, PR China.
Feng
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H
Tang
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Wang
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D004307:Dose-Response Relationship, Radiation; D005030:Ethylenes / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism / Q000528:radiation effects* / Q000648:ultrastructure; D008315:Malondialdehyde / Q000032:analysis; D008563:Membrane Lipids / Q000378:metabolism; D008565:Membrane Proteins / Q000187:drug effects / Q000378:metabolism; D008861:Microsomes / Q000378:metabolism / Q000528:radiation effects* / Q000648:ultrastructure; D010743:Phospholipids / Q000378:metabolism; D010937:Plant Growth Regulators / Q000378:metabolism; D018515:Plant Leaves / Q000528:radiation effects / Q000648:ultrastructure; D012621:Seasons; D013997:Time Factors; D014908:Triticum / Q000502:physiology / Q000528:radiation effects*; D014466:Ultraviolet Rays
D005030:Ethylenes; D008563:Membrane Lipids; D008565:Membrane Proteins; D010743:Phospholipids; D010937:Plant Growth Regulators; D008315:Malondialdehyde; C036216:ethylene