Abstract: Cry proteins with protein engineering modification is an important method to producing new Bt protein. Cry  protein modification involves many techniques, such as domain swapping, site-directed mutagenesis, protein truncation, etc. We obtained a new Bt protein coding genes cryNAc by applying domain swapping and codon optimization against cry1Ab. Then cryNAc was transformed into Jijing88, which is Jilin provinces main rice cultivars, with Agrobacterium mediated. Molecular identification and insect resistance were evaluated against the transgenic descents. The results of molecular detection showed that cryNAc gene was successfully integrated into Jijing88 genome with stable expression. There were significant differences in CryNAc expression in roots, stems and leaves during various developmental stages, with the highest (2 959.73 ng/g) occurring during the grain filling stage in rice leaves and lowest (150.9 ng/g) in tillering stem. cryNAc transgenic rice showed significantly better resistance against Chilo suppressalis. Conclusively，our results supported that cryNAc can be used as a new cry gene for crop genetic improvement.

Key words: transgenic rice, Bacillus thuringiensis(Bt), molecular modification, function evaluation

摘要： 利用蛋白质工程技术对Cry蛋白进行改造是创制新Bt蛋白的主要途径之一。Cry蛋白改造涉及结构域交换、定点突变、蛋白截断等多种方法。利用结构域交换、密码子优化方法对Bt基因进行合理化设计改造，获得新型Bt蛋白编码基因cryNAc，进一步利用农杆菌介导法转入吉林省水稻主栽品种吉粳88中，并开展了转基因后代的分子鉴定和抗虫性功能评价相关研究工作。分子检测结果表明cryNAc基因成功整合进入吉粳88基因组中，且稳定表达；CryNAc蛋白在各个发育时期根、茎、叶中的表达存在显著差异，灌浆期水稻叶片中蛋白表达量最高（2 959.73 ng/g）,分蘖期茎中蛋白表达量最低（150.9 ng/g）；田间接虫试验表明cryNAc转基因水稻抗二化螟的能力显著。上述结果表明cryNAc基因可作为新的cry基因用于作物遗传改良。

关键词: 转基因水稻, 苏云金芽孢杆菌(Bt), 分子改造, 功能评价