Effects of Photosystem II Interfering Herbicides Atrazine and Bentazon on the Soybean Transcriptome 1

Atrazine and bentazon are both photosystem II inhibiting herbicides that interfere with photosynthetic electron transport provoking oxidative stress. While atrazine is lethal to soybean, bentazon does not kill soybeans because of the capability of soybeans to metabolize the herbicide. Gene expression profiling was conducted using cDNA microarrays to understand the responses of soybeans to PSII interruption and concomitant oxidative stress caused by atrazine and bentazon by monitoring expression at 1, 2, 4, and 8 h after treatment (HAT). The microarray study revealed that 6,646 genes were differentially expressed with high statistical significance over the experiment with 88% of them sharing similar expression pattern between the atrazine and bentazon treatments. Many genes related to xenobiotic detoxification and antioxidation such as cytochrome P450s, glutathione-S-transferases, superoxide dismutases, catalases and tocopheral cyclases were induced by the herbicides. The study also discovered plants treated with bentazon started to recover between 4 HAT and 8 HAT as reflected in the decreased amplitude of fold changes of most genes from 4 to 8 HAT. The 12% of the genes that were differentially expressed between atrazine and bentazon were largely related to cell recovery, such as genes related to ribosomal components. Keywords = stress Keywords = GST Keywords = ROS Keywords = D1 protein Keywords = Fuzzy k-means Keywords = plant Keywords: plant xenobiotic interaction loop design, 12 direct comparisons, 2 technical repeats including dye swaps, 3 biological repeats

阿特拉津（Atrazine）与苯达松（bentazon）均为光系统II（photosystem II）抑制剂类除草剂，可通过干扰光合电子传递诱发氧化应激。尽管阿特拉津对大豆具有致死毒性，但苯达松却不会杀伤大豆，这源于大豆具备代谢该类除草剂的能力。
为解析大豆对阿特拉津与苯达松引发的光系统II阻断及伴随氧化应激的响应，本研究采用cDNA微阵列（cDNA microarray）技术开展基因表达谱分析，于处理后1、2、4、8小时（HAT，处理后小时）监测基因表达水平。
该微阵列研究结果显示，本实验中共鉴定出6646个具有显著统计学意义的差异表达基因，其中88%的基因在阿特拉津与苯达松处理组中呈现相似的表达模式。诸多与外源异物解毒及抗氧化相关的基因——如细胞色素P450（cytochrome P450）家族、谷胱甘肽S-转移酶（glutathione-S-transferase, GST）、超氧化物歧化酶、过氧化氢酶以及生育酚环化酶——均被这两种除草剂诱导表达。
本研究同时发现，经苯达松处理的大豆植株在处理后4至8小时开始启动恢复过程，具体体现为多数基因的表达倍数变化幅度在4至8小时间呈下降趋势。而在阿特拉津与苯达松处理组间存在差异表达的12%基因，则主要与细胞恢复相关，例如核糖体组分相关基因。
关键词：胁迫（stress）、谷胱甘肽S-转移酶（GST）、活性氧（ROS）、D1蛋白、模糊k均值（Fuzzy k-means）、植物；实验设计为植物-异源生物互作循环设计，包含12组直接比对、2次技术重复（含染料互换）以及3次生物学重复。