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Pak. J. Bot., 45(3): 813-819, 2013.

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EXOGENOUS APPLICATION OF SODIUM NITROPRUSSIDE ALLEVIATED CADMIUM INDUCED CHLOROSIS, PHOTOSYNTHESIS INHIBITION AND OXIDATIVE STRESS IN CUCUMBER

LIXU YU, RONGXIA GAO, QINGHUA SHI^*, XIUFENG WANG, MIN WEI AND FENGJUAN YANG

Abstract: Cadmium (Cd) is one heavy metal which is toxic and can cause physiological disorder of plants. In the present experiment, effects of Sodium nitroprusside (SNP), a NO donor, on the phenotype, photosynthesis and oxidative stress of cucumber leaves were studied under Cd stress. Application of 100μM CdCl₂ induced obvious chlorosis of cucumber leaves with lower pigment content and lower net photosynthetic rate (P_N). Higher accumulations of H₂O₂ and thiobarbituric acid-reactive substances (TBARS) were observed in Cd-treated cucumber leaves, which indicated Cd induced oxidative stress to cucumber leaves. Application of 100µM SNP reversed the chlorosis and lower P_N induced by Cd treatment. Activities of reactive oxygen species (ROS) scavenging enzymes and antioxidant capacity expressed by α,α-diphenyl-β-picryllhydrazyl (DPPH) scavenging activity, chelating activity of ferrous ions and hydroxyl radical (OH·) scavenging activity were significantly increased by SNP under Cd stress. On the contrary, the above effects of SNP were not observed after the application of potassium ferrocyanide which is an analog of SNP that does not release NO. Therefore, it could be concluded that the NO from SNP might account for the alleviating effect of Cd stress on cucumber plants.

State Key Laboratory of Crop Biology, College of Horticulture Science and Engineering, Shandong Agricultural University, Taian 271018, P.R. China

^*Corresponding author’s e-mail: sqhjc@163.com, qhshi@sdau.edu.cn; Tel: 86-538-8242201