Transcriptome profiling identified genes and pathways associated with arsenic toxicity and tolerance in Arabidopsis. Arabidopsis thaliana

Transcriptional profiling of arsenic-induced toxicity and tolerance in Arabidopsis plants of different ecotypes Arsenic (As) is a toxic metalloid found ubiquitously in the environment and has widely been known as an acute poison and carcinogen. As toxicity is a major factor leading to root growth inhibition in plants. However, the molecular mechanisms of plants in response to As has not been extensively characterized. In this study, Arabidopsis ecotypes that are As-tolerant (Col-0) and -sensitive (Ws-2) were used to conduct a transcriptome analysis of the response to As (V). To begin elucidating the molecular basis of As toxicity and tolerance in Arabidopsis, seedlings of Col-0 and Ws-2 were subjected to As treatment. The root elongation rate of Col-0 was significantly higher than that of Ws-2 when exposed to As. The tolerant ecotype (Col-0) demonstrated lower accumulation of As when compared to the responses observed in the sensitive Ws-2. Subsequently, the effect of As exposure on genome-wide gene expression was examined in the two ecotypes. Comparative analysis of microarray data identified groups of genes with common and specific responses to As between Col-0 and Ws-2. The genes related to heat responses and oxidative stresses belonged to common responses, indicating conserved stress-associated changes across two ecotypes. The majority of specific responsive genes were those encoding heat shock proteins, heat shock factors, ubiquitin and transporters. The data suggested that metal transport and maintenance of protein structure may be important mechanisms for toxicity and tolerance to As. This study presents comprehensive surveys of global transcriptional regulation and identifies stress- and tolerance-associated genes in response to As. Overall design: Comparison of Arabidopsis ecotype Col-0 and Ws-2 in response to As (V) for 1.5 and 3 hr Affymetrix GeneChip assay were performed by the Affymetrix Gene Expression Service Lab (http://ipmb.sinica.edu.tw/affy/), supported by Academia Sinica, Taiwan

不同生态型拟南芥中砷（Arsenic, As）诱导毒性与耐受性的转录组分析

砷是一种广泛分布于环境中的有毒类金属，被公认为急性毒物与致癌物。砷毒性是导致植物根系生长受抑制的主要因素之一，但植物应对砷胁迫的分子机制尚未得到充分解析。本研究选取砷耐受型（Col-0）与敏感型（Ws-2）拟南芥生态型，针对五价砷（As(V)）胁迫开展转录组分析。为解析拟南芥应对砷毒性与耐受性的分子基础，本研究对Col-0与Ws-2的幼苗施加砷胁迫处理。结果显示，暴露于砷环境时，Col-0的根系伸长率显著高于Ws-2；与敏感型Ws-2相比，耐受型生态型Col-0的砷累积量更低。随后，本研究检测了两种生态型中砷暴露对全基因组基因表达的影响。对微阵列数据的比较分析，鉴定出Col-0与Ws-2中存在共同响应与特异性响应砷胁迫的基因簇：热响应与氧化胁迫相关基因属于共同响应基因类群，表明两种生态型间存在保守的胁迫相关表达变化；多数特异性响应基因编码热激蛋白、热激转录因子、泛素及转运蛋白。研究数据表明，金属转运与蛋白质结构维持可能是植物调控砷毒性与耐受性的重要分子机制。本研究全面分析了全局转录调控模式，并鉴定出响应砷胁迫的胁迫相关与耐受性相关基因。

实验整体设计：针对Col-0与Ws-2两种拟南芥生态型，分别在1.5小时与3小时时间点检测其对五价砷（As(V)）的响应。本研究的Affymetrix基因芯片检测由中国台湾中央研究院支持的Affymetrix基因表达服务实验室（http://ipmb.sinica.edu.tw/affy/）完成。