利用小麦乙酰乳酸合成酶基因改良水稻对咪唑啉酮类除草剂抗性的研究

The Imidazolinone herbicides is one of the five well-known herbicides because of thier unique characters such as higher activity, broad- sprectrum weed control,lower dosage application and chronic animal toxicity. They are designed to target the enzyme,Acetolactate Synthase(ALS),in the plant specific branched amino acid synthesis pathways (BCAAs). Research shows that 11 amino acids sites of the crystal subunit binding site of ALS protein are potential target sites to gain resistance to herbicides. Among these 11 sites, One mutation site as Ser627 has been proved to be related to the imidazolinone resistance in rice. However,there are another sites Ala122 is deduced to be closely related to imidazolinone in other crops such as wheat and maize.Although it has been reported that Ser627 mutation can cause rice resistance to Sulfonylurea herbicides,there is a need to create new imidazolinone resistance rice varieties. So, we propose to mutate wheat ALS gene at these two deduced imidazolinone resistant sites and construct vectors with the two muated wheat ALS genes to different promoters. Then, tranform rice with these vectors to get positive transgenic imidazolinone resistance rice. Their resistance to imidazolinone herbicides will be evaluated in the rice field to obtain data to support the hypothesis whether the site is truely a resistance site in rice and how much is the resistance gained in rice.

咪唑啉酮类除草剂是目前世界上应用最广泛的五大类低毒高效的除草剂之一，其靶标基因是植物特有的支链氨基酸合成途径(BCAAs)中的乙酰乳酸合成酶（ALS）。已有研究表明，ALS基因编码的功能蛋白质，其底物结合区的11个氨基酸位点如果发生点突变，可以导致突变作物对除草剂的抗性大幅提高。许多天然和人工筛选培育的ALS突变体除草剂抗性品种被开发应用，且被证实是ALS基因点突变的结果。已知水稻的Ser627位点突变与咪唑啉酮类除草剂有关，而小麦和玉米中另一个位点Ala122也与该类除草剂抗性相关。虽然水稻中已有Ser627位点突变体抗磺酰脲类除草剂，但还没有咪唑啉酮类除草剂抗性点突变体的报道。本研究拟克隆小麦ALS基因，通过体外定点突变技术对小麦ALS基因已知位点进行分子改造；并将该突变基因与不同强度启动子构建载体转化水稻；并对转基因阳性植株进行咪唑啉酮类除草剂抗性筛选和评价。