Paulose et al. BMC Plant Biology 2010, 10:108 http://www.biomedcentral.com/1471-2229/10/108 Open Access RESEARCH ARTICLE © 2010 Paulose et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Research article Expression profiling of Crambe abyssinica under arsenate stress identifies genes and gene networks involved in arsenic metabolism and detoxification Bibin Paulose 1 , Suganthi Kandasamy 1,2 and Om Parkash Dhankher* 1 Abstract Background: Arsenic contamination is widespread throughout the world and this toxic metalloid is known to cause cancers of organs such as liver, kidney, skin, and lung in human. In spite of a recent surge in arsenic related studies, we are still far from a comprehensive understanding of arsenic uptake, detoxification, and sequestration in plants. Crambe abyssinica, commonly known as 'abyssinian mustard', is a non-food, high biomass oil seed crop that is naturally tolerant to heavy metals. Moreover, it accumulates significantly higher levels of arsenic as compared to other species of the Brassicaceae family. Thus, C. abyssinica has great potential to be utilized as an ideal inedible crop for phytoremediation of heavy metals and metalloids. However, the mechanism of arsenic metabolism in higher plants, including C. abyssinica, remains elusive. Results: To identify the differentially expressed transcripts and the pathways involved in arsenic metabolism and detoxification, C. abyssinica plants were subjected to arsenate stress and a PCR-Select Suppression Subtraction Hybridization (SSH) approach was employed. A total of 105 differentially expressed subtracted cDNAs were sequenced which were found to represent 38 genes. Those genes encode proteins functioning as antioxidants, metal transporters, reductases, enzymes involved in the protein degradation pathway, and several novel uncharacterized proteins. The transcripts corresponding to the subtracted cDNAs showed strong upregulation by arsenate stress as confirmed by the semi-quantitative RT-PCR. Conclusions: Our study revealed novel insights into the plant defense mechanisms and the regulation of genes and gene networks in response to arsenate toxicity. The differential expression of transcripts encoding glutathione-S- transferases, antioxidants, sulfur metabolism, heat-shock proteins, metal transporters, and enzymes in the ubiquitination pathway of protein degradation as well as several unknown novel proteins serve as molecular evidence for the physiological responses to arsenate stress in plants. Additionally, many of these cDNA clones showing strong upregulation due to arsenate stress could be used as valuable markers. Further characterization of these differentially expressed genes would be useful to develop novel strategies for efficient phytoremediation as well as for engineering arsenic tolerant crops with reduced arsenic translocation to the edible parts of plants. Background Arsenic (As) is ubiquitous in the earth's crust and has widely been known as an acute poison and carcinogen [1,2]. Chronic As ingestion from contaminated food sup- plies and drinking water is strongly associated with an increased risk of liver, kidney, skin, and lung cancer [1]. Inorganic forms of arsenic, pentavalent arsenate (AsV) and trivalent arsenite (AsIII), are more toxic than the organic forms and are highly abundant in the environ- ment. High levels of As in soil and drinking water have been reported around the world including Bangladesh, India, USA, and South America, where As in drinking water exceeds 10 ppb, the permissible limit established by the World Health Organization [3]. Industrial and agri- cultural practices, including the use of As in pesticides and herbicides [4], wood preservatives [5], and irrigation with contaminated groundwater [6,7], have significantly increased As levels in agricultural soils. Several studies * Correspondence: parkash@psis.umass.edu 1 Department of Plant, Soil, and Insect Sciences, University of Massachusetts, Amherst, MA 01002, USA Full list of author information is available at the end of the article