Characterization of an acetohydroxy acid synthase mutant conferring tolerance to imidazolinone herbicides in rice (Oryza sativa)
Characterization of an acetohydroxy acid synthase mutant conferring tolerance to imidazolinone herbicides in rice (Oryza sativa)
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DOI：
10.1007/s00425-017-2817-2
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发表时间：
2018-03-01
期刊：
影响因子：
4.3
通讯作者：
Fang, Jun
中科院分区：
文献类型：
--
作者：
Piao, Zhongze;Wang, Wei;Fang, Jun
乙酰羟酸合成酶S627N突变赋予水稻除草剂耐受性，并且含有该突变的水稻品种产生良好的产量。该品种在中国上海和江苏地区具有商业可行性。杂草稻是一种比栽培稻产量低、品质差的水稻。它困扰着许多国家的商业稻田。控制其扩散的一个策略是开发对特定除草剂耐受的水稻品种。乙酰羟酸合成酶（AHAS）突变已被发现赋予水稻除草剂耐受性。在这里，我们确定了一个单一的突变（S627 N）AHAS从籼稻品种，赋予对咪唑啉酮类除草剂，包括咪唑乙烟酸和甲氧咪草烟的耐受性。通过导入突变的籼型ahas基因，培育出耐除草剂的粳稻品种JD 164。在JD 164田，施用咪唑啉酮足以有效地控制杂草稻。尽管咪唑乙烟酸处理导致JD 164植株矮化，但其并未显著降低产量。为了确定施用咪唑乙烟酸后玉米植株矮化是否与ahas mRNA表达的降低有关，我们检测了玉米植株ahas mRNA的水平。在施用咪唑啉酮后，JD164中ahas mRNA的丰度增加，因此排除了作为侏儒症的可能原因的mRNA表达水平。活性测定表明，突变的AHAS是耐受咪唑啉酮，但突变的AHAS的催化效率下降，在其存在下。此外，突变的AHAS的活性在咪唑乙烟酸的存在下比在甲氧咪草烟的存在下降低更多。我们没有观察到AHAS二级结构的差异，但同源性建模表明，S627N突变使底物能够进入AHAS中的活性位点通道，导致咪唑啉酮耐受性。本研究将除草剂与一个水稻品种相结合，对杂草稻进行了控制，并揭示了该水稻品种对除草剂的耐受机制。
The acetohydroxy acid synthase S627N mutation confers herbicide tolerance in rice, and the rice variety containing this mutation produces good yields. This variety is commercially viable at Shanghai and Jiangsu regions in China.Weedy rice is a type of rice that produces lower yields and poorer quality grains than cultivated rice. It plagues commercial rice fields in many countries. One strategy to control its proliferation is to develop rice varieties that are tolerant to specific herbicides. Acetohydroxy acid synthase (AHAS) mutations have been found to confer herbicide tolerance to rice. Here, we identified a single mutation (S627N) in AHAS from an indica rice variety that conferred tolerance against imidazolinone herbicides, including imazethapyr and imazamox. A japonica rice variety (JD164) was developed to obtain herbicide tolerance by introducing the mutated indica ahas gene. Imidazolinone application was sufficient to efficiently control weedy rice in the JD164 field. Although the imazethapyr treatment caused dwarfing in the JD164 plants, it did not significantly reduce yields. To determine whether the decrease of the ahas mRNA expression caused the dwarfism of JD164 after imazethapyr application, we detected the ahas mRNA level in plants. The abundance of the ahas mRNA in JD164 increased after imidazolinone application, thus excluding the mRNA expression level as a possible cause of dwarfism. Activity assays showed that the mutated AHAS was tolerant to imidazolinone but the catalytic efficiency of the mutated AHAS decreased in its presence. Moreover, the activity of the mutated AHAS decreased more in the presence of imazethapyr than in the presence of imazamox. We observed no difference in the AHAS secondary structures, but homology modeling suggested that the S627N mutation enabled the substrate to access the active site channel in AHAS, resulting in imidazolinone tolerance. Our work combined herbicides with a rice variety to control weedy rice and showed the mechanism of herbicide tolerance in this rice variety.