Comparative Study on Three Pairs of Specific Primers to Rapidly Identify Phytophthora nicotianae

In order to rapidly identify the Phytophthora nicotianae Breda de Haan from different origins, a pair of specific primers ITS8-1 / ITS8-2 was designed,then combined with SP / AP and Pn1 / Pn2 which was reported specific primers to extract the Phytophthora nicotianae DNA from 22 different sampling points by PCR amplification. Results showed that the specific primers Pn1 / Pn2 and SP / AP could not amplify these all 22 isolates of Phytophthora nicotianae or the bands were not very feeble. Conversely, the specific primer ITS8-1 / ITS8-2 were capable of amplifying all the tested strains and with clear band, which indicated that the latter had strongly specificity than formers. After screening the genomic DNA of some other roots disease germs and tobacco,the infected by P. nicotianae tissue and disease soil,it was revealed that ITS8-1 / ITS8-2 primers amplified only a single product about 364 bp,and its sequence homology was 100% refer to Phytophthora nicotianae. It is suggested that the species-specific primersITS8-1 / ITS8-2 can identify the isolates of P. nicotianae sampled in different sites.