Journal of Biological Systems, Vol. 18, No. 1 (2010) 223–241 c  World Scientific Publishing Company DOI: 10.1142/S0218339010003214 ARSENIC ACCUMULATION IN PLANTS — OUTLINING STRATEGIES FOR DEVELOPING IMPROVED VARIETY OF CROPS FOR AVOIDING ARSENIC TOXICITY IN FOODS DAN LUNDH, * DENNIS LARSSON, NOOR NAHAR and ABUL MANDAL School of Life Science, University of Sk¨ ovde P.O. Box 408, SE-54128 Sk¨ ovde, Sweden * dan.lundh@his.se Received 11 March 2009 Accepted 2 July 2009 Contamination of food with arsenics is a potential health risk for both humans and animals in many regions of the world, especially in Asia. Arsenics can be accumulated in humans, animals and plants for a longer period and a long-term exposure of humans to arsenics results in severe damage of kidney, lever, heart etc. and many other vascular diseases. Arsenic contamination in human may also lead to development of cancer. In this paper we report our results on data mining approach (an in silico analysis based on searching of the existing genomic databases) for identification and characterization of genes that might be responsible for uptake, accumulation or metabolism of arsenics. For these in silico analyses we have involved the model plant Arabidopsis thaliana in our investigation. By employing a system biology model (a kinetic model) we have studied the molecular mechanisms of these processes in this plant. This model contains equations for uptake, metabolism and sequestration of different types of arsenic; As(V), As(III), MMAA and DMAA. The model was then implemented in the software XPP. The model was also validated against the data existing in the literatures. Based on the results of these in silico studies we have developed some strategies that can be used for reducing arsenic contents in different parts of the plant. Data mining experiments resulted in iden- tification of two candidate genes (ACR2, arsenate reductase 2 and PCS1, phytochelatin synthase 1) that are involved either in uptake, transport or cellular localization of arsenic in A. thaliana. However, our system biology model revealed that by increasing the level of arsenate reductase together with an increased rate of arsenite sequestration in the vacuoles (by involving an arsenite efflux pump MRP1/2), it is possible to reduce the amount of arsenics in the shoots of A. thaliana to 11–12%. Keywords : Arsenic Toxicity; Arsenic Accumulation; Kinetic Model; Strategy for Arsenics. 1. Introduction Arsenic (As) is a metalloid element naturally occurring in the environment. 1 Arsenic is also toxic to most organisms. 1,2 Accumulation of arsenics in food has been previ- ously reported elsewhere as a major health risk. Long-term exposure of humans to this toxic metalloid causes severe damage to organs in humans like kidney, liver etc. and it may also lead to development of cancer. 3–5 In 2001 about 200,000 to 275,000 deaths in Bangladesh were caused by cancer diseases that have been resulted from 223 J. Biol. Syst. 2010.18:223-241. Downloaded from www.worldscientific.com by WSPC on 09/30/13. For personal use only.