Advanced Genetic Sciences, Inc., 6701 San Pablo Avenue, Oakland, CA 94608, USA.
EMBO J. 1988 May;7(5):1241-8. doi: 10.1002/j.1460-2075.1988.tb02937.x.
The enzyme acetolactate synthase (ALS) is the target enzyme for the sulfonylurea and imidazolinone herbicides. We describe the isolation and characterization of the ALS genes from two herbicide-resistant mutants, C3 and S4-Hra, of Nicotiana tabacum. There are two distinct ALS genes in tobacco which are 0.7% divergent at the amino acid sequence level. The C3 mutant has a single Pro-Gln replacement at amino acid 196 in one ALS gene. This gene is termed the class I gene and is equivalent to the SuRA locus. The S4-Hra mutant has two amino acid changes in the other ALS gene. This gene is termed the class II gene or the SuRB locus. The S4-Hra mutant includes a Pro-Ala substitution at amino acid 196 and a Trp-Leu substitution at amino acid 573. Gene reintroduction experiments have confirmed that these amino acid substitutions are responsible for the herbicide resistance phenotypes. Transgenic plants carrying these genes are highly resistant to sulfonylurea herbicide applications.
乙酰乳酸合成酶（ALS）是磺酰脲类和咪唑啉酮类除草剂的靶标酶。我们从两个除草剂抗性突变体 C3 和 S4-Hra 中分离和鉴定了烟草 ALS 基因。烟草中有两个不同的 ALS 基因，其氨基酸序列水平上有 0.7%的差异。C3 突变体在一个 ALS 基因的第 196 位氨基酸处发生单个脯氨酸-谷氨酰胺取代。该基因称为 I 类基因，与 SuRA 基因座等同。S4-Hra 突变体在另一个 ALS 基因中有两个氨基酸变化。该基因称为 II 类基因或 SuRB 基因座。S4-Hra 突变体包括第 196 位氨基酸的脯氨酸-丙氨酸取代和第 573 位氨基酸的色氨酸-亮氨酸取代。基因回补实验证实这些氨基酸取代是导致除草剂抗性表型的原因。携带这些基因的转基因植物对磺酰脲类除草剂的应用具有高度抗性。
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