Guo Bing-Fu, Hong Hui-Long, Sun Li-Ping, Guo Yong, Qiu Li-Juan
The National Key Facility for Crop Gene Resources and Genetic Improvement (NFCRI) and MOA Key Lab of Soybean Biology (Beijing), Institute of Crop Science, Chinese Academy of Agricultural Sciences, No. 12 Zhongguancun South Street, Haidian District, Beijing, 100081, People's Republic of China.
Jiangxi Province Key Laboratory of Oilcrops Biology, Crops Research Institute of Jiangxi Academy of Agricultural Sciences, Nanchang, China.
Mol Biol Rep. 2021 Nov;48(11):7351-7360. doi: 10.1007/s11033-021-06742-x. Epub 2021 Oct 21.
Glyphosate is a broad-spectrum, non-selective systemic herbicide. Introduction of glyphosate tolerance genes such as EPSPS or detoxification genes such as GAT can confer glyphosate tolerance on plants. Our previous study revealed that co-expression of EPSPS and GAT genes conferred higher glyphosate tolerance without "yellow flashing". However, the plant response to glyphosate at the transcriptional level was not investigated.
To investigate the glyphosate tolerance mechanism, RNA-seq was conducted using four soybean genotypes, including two non-transgenic (NT) soybeans, ZH10 and MD12, and two GM soybeans, HJ698 and ZH10-6. Differentially expressed genes (DEGs) were identified in these soybeans before and after glyphosate treatment. Similar response to glyphosate in the two NT soybeans and the different effects of glyphosate on the two GM soybeans were identified. As treatment time was prolonged, the expression level of some DEGs involved in shikimate biosynthetic pathway and herbicide targeted cross-pathways was increased or declined continuously in NT soybeans, and altered slightly in HJ698. However, the expression level of some DEGs was altered in ZH10-6 at 12 hpt, while similar expression level of some DEGs involved in shikimate biosynthetic pathway and herbicide targeted cross-pathways was observed in ZH10-6 at 0 hpt and 72 hpt. These observations likely explain the higher glyphosate tolerance in ZH10-6 than in HJ698 and NT soybeans.
These results suggested that GAT and EPSPS genes together play a crucial role in response to glyphosate, the GAT gene may work at the early stage of glyphosate exposure, whereas the EPSPS gene may be activated after the uptake of glyphosate by plants. These findings will provide valuable insight for the molecular basis underlying glyphosate tolerance or glyphosate detoxication.
草甘膦是一种广谱、非选择性的内吸性除草剂。引入草甘膦耐受性基因如5-烯醇丙酮酰莽草酸-3-磷酸合酶（EPSPS）或解毒基因如草甘膦-N-乙酰转移酶（GAT）可使植物具有草甘膦耐受性。我们之前的研究表明，EPSPS和GAT基因的共表达赋予了更高的草甘膦耐受性且无“黄化闪烁”现象。然而，尚未研究植物在转录水平对草甘膦的反应。
为了研究草甘膦耐受性机制，对四种大豆基因型进行了RNA测序，包括两种非转基因（NT）大豆ZH10和MD12，以及两种转基因大豆HJ698和ZH10-6。在草甘膦处理前后鉴定出这些大豆中的差异表达基因（DEG）。发现两种NT大豆对草甘膦有相似反应，而草甘膦对两种转基因大豆有不同影响。随着处理时间延长，参与莽草酸生物合成途径和除草剂靶向交叉途径的一些DEG的表达水平在NT大豆中持续升高或降低，在HJ698中略有变化。然而，在处理后12小时，ZH10-6中一些DEG的表达水平发生了变化，而在处理前0小时和处理后72小时，ZH10-6中参与莽草酸生物合成途径和除草剂靶向交叉途径的一些DEG的表达水平相似。这些观察结果可能解释了ZH10-6比HJ698和NT大豆具有更高的草甘膦耐受性。
这些结果表明，GAT和EPSPS基因共同在对草甘膦的反应中起关键作用，GAT基因可能在草甘膦暴露的早期起作用，而EPSPS基因可能在植物吸收草甘膦后被激活。这些发现将为草甘膦耐受性或草甘膦解毒的分子基础提供有价值的见解。
