Open Access Research Article Expression Profiling of Crambe Abyssinica under Arsenate Stress Identifies Genes and Gene Networks Involved in Arsenic Metabolism and Detoxification
Open Access Research Article Expression Profiling of Crambe Abyssinica under Arsenate Stress Identifies Genes and Gene Networks Involved in Arsenic Metabolism and Detoxification
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Bibin Paulose;S. Kandasamy;Om Parkash Dhankher
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作者：
Bibin Paulose;S. Kandasamy;Om Parkash Dhankher
背景：砷污染在世界范围内广泛存在，这种有毒的类金属已知会导致人类肝脏、肾脏、皮肤和肺部等器官的癌症。尽管最近与砷相关的研究激增，但我们距离植物对砷的吸收、解毒和封存的全面了解还很远。海甘蓝，俗称“阿比西尼亚芥末”，是一种非食品、高生物量油料种子作物，对重金属具有天然耐受性。此外，与十字花科的其他物种相比，它积累的砷含量明显更高。因此，C. abyssinica 具有作为重金属和类金属植物修复的理想非食用作物的巨大潜力。然而，包括阿比西尼卡在内的高等植物中砷代谢的机制仍然难以捉摸。结果：为了鉴定差异表达的转录本以及参与砷代谢和解毒的途径，对阿比西尼卡植物进行砷盐胁迫，并采用 PCR-选择抑制消减杂交 (SSH) 方法。对总共 105 个差异表达的消减 cDNA 进行了测序，发现它们代表 38 个基因。这些基因编码作为抗氧化剂、金属转运蛋白、还原酶、参与蛋白质降解途径的酶的蛋白质，以及一些新的未表征的蛋白质。半定量 RT-PCR 证实，与扣除的 cDNA 相对应的转录物显示出砷酸盐胁迫的强烈上调。结论：我们的研究揭示了植物防御机制以及响应砷酸盐毒性的基因和基因网络调节的新见解。编码谷胱甘肽-S-转移酶、抗氧化剂、硫代谢、热休克蛋白、金属转运蛋白、蛋白质降解泛素化途径中的酶以及一些未知的新型蛋白质的转录本的差异表达，可作为植物对砷盐胁迫的生理反应的分子证据。此外，许多由于砷酸盐胁迫而表现出强烈上调的 cDNA 克隆可以用作有价值的标记。这些差异表达基因的进一步表征将有助于开发有效植物修复的新策略以及工程化耐砷作物以减少砷向植物可食用部分的易位。背景砷（As）在地壳中普遍存在，被广泛认为是一种急性毒物和致癌物质[1,2]。慢性摄入受污染的食品和饮用水与肝癌、肾癌、皮肤癌和肺癌的风险增加密切相关[1]。砷的无机形式，五价砷酸盐 (AsV)
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 supplies 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)