Copy Number Variation in Acetolactate Synthase Genes of Thifensulfuron-Methyl Resistant Alopecurus aequalis (Shortawn Foxtail) Accessions in Japan.
Copy Number Variation in Acetolactate Synthase Genes of Thifensulfuron-Methyl Resistant Alopecurus aequalis (Shortawn Foxtail) Accessions in Japan.
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DOI：
10.3389/fpls.2017.00254
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发表时间：
2017
影响因子：
5.6
通讯作者：
Tominaga T
中科院分区：
文献类型：
--
作者：
Iwakami S;Shimono Y;Manabe Y;Endo M;Shibaike H;Uchino A;Tominaga T
在日本，即使施用了磺酰脲类除草剂噻吩磺隆，也会发生看麦娘（Alopecurus aequalis）（短褐色狐尾草）（一种小麦和大麦种植系统中的有害杂草）的严重侵扰。本研究对9份A.测试了生长在单个麦田中的小麦对噻吩磺隆的敏感性。七个加入幸存的应用标准田间率的噻吩磺隆，表明严重的侵扰可能导致除草剂抗性。乙酰乳酸合成酶（ALS）是SU除草剂的靶标酶。因此，分离编码ALS的全长基因以确定SU抗性的机制。结果表明，ALS基因拷贝数在不同品种间存在差异。两个拷贝，ALS1和ALS2，在所有的加入，而一些进行两个额外的拷贝，ALS3和ALS4。ALS3和ALS4中的单碱基缺失进一步表明它们代表假基因。没有观察到两个或四个拷贝的ALS基因的加入之间的倍性水平的差异，这表明拷贝数不同。发现抗性植物在ALS1或ALS2基因中携带突变，所有突变均导致Pro 197残基处的氨基酸取代，这已知赋予SU抗性。通过逆转录PCR证实了每个ALS基因拷贝的转录，支持这些突变参与SU抗性。本文报道了A. Aequalis将有助于未来的抗性机制分析。
Severe infestations of Alopecurus aequalis (shortawn foxtail), a noxious weed in wheat and barley cropping systems in Japan, can occur even after application of thifensulfuron-methyl, a sulfonylurea (SU) herbicide. In the present study, nine accessions of A. aequalis growing in a single wheat field were tested for sensitivity to thifensulfuron-methyl. Seven of the nine accessions survived application of standard field rates of thifensulfuron-methyl, indicating that severe infestations likely result from herbicide resistance. Acetolactate synthase (ALS) is the target enzyme of SU herbicides. Full-length genes encoding ALS were therefore isolated to determine the mechanism of SU resistance. As a result, differences in ALS gene copy numbers among accessions were revealed. Two copies, ALS1 and ALS2, were conserved in all accessions, while some carried two additional copies, ALS3 and ALS4. A single-base deletion in ALS3 and ALS4 further indicated that they represent pseudogenes. No differences in ploidy level were observed between accessions with two or four copies of the ALS gene, suggesting that copy number varies. Resistant plants were found to carry a mutation in either the ALS1 or ALS2 gene, with all mutations causing an amino acid substitution at the Pro197 residue, which is known to confer SU resistance. Transcription of each ALS gene copy was confirmed by reverse transcription PCR, supporting involvement of these mutations in SU resistance. The information on the copy number and full-length sequences of ALS genes in A. aequalis will aid future analysis of the mechanism of resistance.