We find that bt cotton has different bt toxin protein content in different tissue and growing period using elisa method . leaves and flower petals contain more bt toxin protein than boll and bracteal leaves 用elisa方法检测bt棉杀虫蛋白的含量，结果表明，棉叶和花瓣杀虫蛋白含量最高，铃和蕾次之。
