APPLICATION OF A PCR-BASED TEST FOR DETECTION OF POTATO LATE BLIGHT AND PINK POT IN TUBERS

A polymerase chain reaction (PCR)-based test for potato late blight (P hytophthora infestans) and pink rot (P. erythroseptica, P. nicotianae) diseases has been developed for use with potato tuber tissue. Primers based on sequence analysis of the ITS2 region of ribosomal DNA of lat e blight and pink rot pathogens were utilized in PCR assays of inocula ted tubers and tubers harvested from plots known to have late blight a nd/or pink rot. Assays of artificially inoculated Kennebec and Russet Burbank tubers revealed that P. infestans was detected by PCR as early as 72 h after inoculation and in the absence of visible symptoms. Muc h higher detection frequencies were obtained by PCR compared with plat ing on selective medium or placement of tissue in moist chambers. Tube rs from plots known to have late blight and/or pink rot mere tested us ing the PCR assay. Assay of late blight lesions showed ca. 80% recover y for late blight-infected tubers horn the field. Results indicate tha t the PCR assay provides a rapid and accurate test for diagnosis of la te blight and pink rot in potato tubers.