Abstract:

Phytophthora nicotianae is a conventional soil-borne plant pathogens，which induces tobacco black shank and causes great financial loss to tobacco industry. Accurate quantity analysis of P. nicotianae in soil helps researchers acquire their distribution, density and dynamics，provide information for disaster forecast and minimizes the economic losses. Pour plate method was used to separate the fungi on the selective medium，and then DNA of the fungal strain was extracted by the method for mini-preparation of fungal DNA from the plate. After that the selected 7 strains were tested by PCR with specific primers. The results showed that specific gene fragments of P. nicotianae with the length of 737bp were obtained from 6 of 7 strains. Further ITS testing found their gene sequence to be in good agreement with that of the reported Phytophthora nicotianae by 99%. Those proved the 6 strains were P. nicotianae in certain. This method has advantages over others in accuracy, cost and ease for application.