ISO/TS 21569-4:20 16规定了用于检测来自根癌农杆菌的胭脂碱合酶基因(P-nos)的启动子区的DNA序列的程序和用于检测来自大肠杆菌K12的Tn5转座子的P-nos和新霉素磷酸转移酶基因(nptII)之间的DNA转换序列的程序。nos启动子和P-nos-nptII-构建体经常存在于遗传修饰的植物中。P-nos和P-nos-nptII特异性方法基于实时PCR，可用于定性筛选目的。为了鉴定和定量特定的转基因植物（事件），必须进行后续分析。 所述方法适用于从食品中提取的DNA的分析。它们也可适用于分析从其它产品如饲料和种子中提取的DNA。这些方法的应用需要从相关基质中提取足够量的可扩增DNA。 通过P-nos元件特异性方法扩增的DNA序列可以在含有根癌农杆菌天然存在的Ti质粒DNA的样品中检测。因此，有必要确认阳性筛查结果。需要使用构建体特异性或事件特异性方法进行进一步分析。

ISO/TS 21569-4:2016 specifies a procedure for the detection of a DNA sequence of the promoter region of the nopaline synthase gene (P-nos) from Agrobacterium tumefaciens and a procedure for the detection of the DNA transition sequence between P-nos and the neomycin-phosphotransferase gene (nptII) from the Tn5 transposon of Escherichia coli K12. The nos-promoter and the P-nos-nptII-construct are frequently found in genetically modified plants. The P-nos and P-nos-nptII specific methods are based on real-time PCR and can be used for qualitative screening purposes. For identification and quantification of a specific genetically modified plant (event) a follow-up analysis has to be carried out. The methods described are applicable for the analysis of DNA extracted from foodstuffs. They may also be suitable for the analysis of DNA extracted from other products such as feedstuffs and seeds. The application of these methods requires the extraction of an adequate amount of amplifiable DNA from the relevant matrix. The DNA sequence amplified by the P-nos element-specific method can be detected in samples which contain DNA of the naturally occurring Ti-plasmid of A. tumefaciens. For this reason, it is necessary to confirm a positive screening result. Further analyses are required using construct-specific or event specific methods.