目前广泛采用的抗菌素或抗除草剂基因作为植物转化筛选标记基因可能带来转基因逃逸 ,因此寻找能够用于植物转化的来源于植物本身的筛选基因是解决这一问题的方法之一。通过从烟草中克隆的邻氨基苯甲酸合成酶基因 (ASA2 )作为筛选标记基因 ,并采用氨基酸的类似物 5 甲基色氨酸为筛选剂 ,进行了农杆菌介导的大豆成熟胚尖转化研究。Southern杂交结果表明ASA2基因成功整合到大豆基因组 ,Northern杂交也显示该基因在转化大豆叶片中表达。HPLC检测转化大豆叶片游离色氨酸的含量比野生型要高 5 9%～ 12 3%。PCR检测转化子 1代结果显示转化基因通过孟德尔规律稳定遗传。这些结果表明反馈抑制不敏感ASA2基因可以作为筛选标记基因用于大豆遗传转化。同时也证实来源于一种植物 (烟草 )编码的邻氨基苯甲酸α 亚基能够与另一种植物 (大豆 )编码该酶的 β 亚基结合形成具有完整活性的邻氨基苯甲酸合成酶。对ASA2基因作为一种新的植物转化筛选标记基因的优缺点进行了讨论 Currently widely used antibiotics or herbicide resistance genes as plant transformation screening marker gene may bring about gene escape, so looking for plants can be used for plant transformation derived from the screening of genes is one of the ways to solve this problem. Agrobacterium-mediated transformation of mature embryos in soybean was performed by using anthranilate synthase gene (ASA2) cloned from tobacco as a screening marker gene and amino acid analogue 5-methyltryptophan as screening agent . Southern blot results showed that the ASA2 gene was successfully integrated into the soybean genome and Northern blotting also showed that the gene was expressed in transformed soybean leaves. The content of free tryptophan in soybean leaves transformed by HPLC was 59% ~ 123% higher than that of wild type. PCR results of the first generation of transformants showed that the transgene was stably inherited by Mendelian law. These results indicate that feedback inhibition is not sensitive to the ASA2 gene as a selectable marker gene for soybean genetic transformation. At the same time, it was also confirmed that α-subunit of anthranilate encoded by one plant (tobacco) can bind to β-subunit of the other plant (soybean) which encodes this enzyme to form anthranilate synthase with complete activity. The ASA2 gene as a new plant transformation screening marker gene advantages and disadvantages were discussed