Abercrombie Jason M, Halfhill Matthew D, Ranjan Priya, Rao Murali R, Saxton Arnold M, Yuan Joshua S, Stewart C Neal
Department of Plant Sciences, University of Tennessee, 2431 Joe Johnson Blvd., Knoxville, TN 37996-4561, USA.
BMC Plant Biol. 2008 Aug 6;8:87. doi: 10.1186/1471-2229-8-87.
Arsenic is toxic to plants and a common environmental pollutant. There is a strong chemical similarity between arsenate [As (V)] and phosphate (Pi). Whole genome oligonucleotide microarrays were employed to investigate the transcriptional responses of Arabidopsis thaliana plants to As (V) stress.
Antioxidant-related genes (i.e. coding for superoxide dismutases and peroxidases) play prominent roles in response to arsenate. The microarray experiment revealed induction of chloroplast Cu/Zn superoxide dismutase (SOD) (at2g28190), Cu/Zn SOD (at1g08830), as well as an SOD copper chaperone (at1g12520). On the other hand, Fe SODs were strongly repressed in response to As (V) stress. Non-parametric rank product statistics were used to detect differentially expressed genes. Arsenate stress resulted in the repression of numerous genes known to be induced by phosphate starvation. These observations were confirmed with qRT-PCR and SOD activity assays.
Microarray data suggest that As (V) induces genes involved in response to oxidative stress and represses transcription of genes induced by phosphate starvation. This study implicates As (V) as a phosphate mimic in the cell by repressing genes normally induced when available phosphate is scarce. Most importantly, these data reveal that arsenate stress affects the expression of several genes with little or unknown biological functions, thereby providing new putative gene targets for future research.
砷对植物有毒，是一种常见的环境污染物。砷酸盐[As(V)]与磷酸盐（Pi）在化学性质上有很强的相似性。利用全基因组寡核苷酸微阵列研究拟南芥植物对As(V)胁迫的转录反应。
抗氧化相关基因（即编码超氧化物歧化酶和过氧化物酶的基因）在对砷酸盐的反应中起重要作用。微阵列实验显示叶绿体铜/锌超氧化物歧化酶（SOD）（at2g28190）、铜/锌SOD（at1g08830）以及一种SOD铜伴侣蛋白（at1g12520）被诱导。另一方面，铁超氧化物歧化酶在As(V)胁迫下受到强烈抑制。使用非参数秩积统计来检测差异表达基因。砷酸盐胁迫导致许多已知受磷饥饿诱导的基因受到抑制。这些观察结果通过定量逆转录聚合酶链反应（qRT-PCR）和SOD活性测定得到证实。
微阵列数据表明As(V)诱导参与氧化应激反应的基因，并抑制磷饥饿诱导基因的转录。本研究表明As(V)在细胞中作为磷酸盐模拟物，通过抑制在可用磷酸盐稀缺时正常诱导的基因发挥作用。最重要的是，这些数据揭示砷酸盐胁迫影响了几个生物学功能很少或未知的基因的表达，从而为未来的研究提供了新的假定基因靶点。
