Response of Arabidopsis thaliana seedlings to lead exposure: effect of pre-treatment with sodium nitroprusside

• Main Authors: Phang, Ing Chia, Leung, David W. M., Taylor, H. Harry, Burritt, David J.
• Format: Conference or Workshop Item
• Language: English
• Published: 2009
• Subjects: Q Science (General)
• Online Access: http://irep.iium.edu.my/11554/1/Updated_Conference_Programme_and_Abstracts.pdf; http://irep.iium.edu.my/11554/

Heavy metal pollution has become a serious public health and environmental concern. The physical properties of lead (Pb), including low melting point and excellent corrosion resistance, have resulted in the extensive use of Pb. High level of Pb contamination has been reported in Tamaki Estuary, Auckland and Canterbury. These Pb contaminants are susceptible to enter human’s food chain, affecting the nervous system, kidney function and reproduction system. Phytoremediation is an emerging low-cost and ecologically friendly alternative to remove pollutants from the environment because heavy metal contaminants cannot be mineralized. Plants are able to bioaccumulate these heavy metals in their aerial parts. The heavy metals contained therein can be recovered and further concentrated by incineration or recycled for industrial use. Plants used for Pb phytoremediation are also subjected to oxidative stress, in which reactive oxygen species (ROS) are overproduced. Therefore, plants exposed to Pb stress initiate signaling pathways, and make specific changes in their cell physiology to avoid or tolerate the stress. The mechanisms to reduce the effects of Pb may vary from plant to plant, developmental stage, and culture medium. Nitric oxide (NO) is an important signalling molecule in plant development and defence responses. It has been shown to play a major role in plant responses to several abiotic stresses, such as heat, chilling, drought, salt, UV irradiation and ozone exposure. Depending on its concentration, NO provokes both beneficial and harmful effects in plants. The objective of this study is to examine the protective effect of an exogenously supply of sodium nitroprusside (SNP), a NO donor, on early seedlings. All experiments studying the physiological and biochemical responses of 7-day-old Arabidopsis thaliana seedlings pre-treated with SNP to Pb exposure were carried out in a laboratory environment. Pb contents were determined using a graphite furnace spectrometer. Antioxidant assays and ROS were carried out using a microplate reader. A major finding is that Pb treatment resulted in increased oxidative stress, which was counteracted by SNP pre-treatment. This and other results obtained are discussed in relation to a strategy to tolerate Pb accumulation in plant cells.