Serological and molecular detection of late blight pathogen and disease development in potato

In the present work, we investigated the specificity and sensitivity of serological and molecular tools for the detection of Phytophthora infestans in infected tissues of susceptible and resistant potato cultivars and to study disease development among these cultivars. Serological tools [enzyme-linked immunosorbent assay (ELISA) and dot blot immunoassay (DIA)] were performed using antiserum raised from soluble mycelial protein of P. infestans, while molecular tool [Polymerase chain reaction (PCR)] was performed using specific primer to P. infestans, which designed on the basis of internally transcribed spacer 1 ITS1 (GenBank accession no AY770739). Cross-reactivity of the antiserum was tested against 50 mug antigens of 9 isolates of P. infestans and antigens of Fusarium sp., Pythium sp., R. solani, M. phaseolina, A. solani, E. carotovora and R. solanacearum. Results showed that the antiserum was adequate specificity among different antigens of the tested isolates of P. infestans. On the other hand, PCR amplification indicated that, all the P. infestans isolates amplified a product of approximately 813bp with the primer. While no amplification products were obtained with the other tested genera. The detection sensitivity of the antiserum ranged from 5-50 mug of P. infestans antigen. The PCR assay was also very sensitive for detecting P. infestans, only 1pg of purified DNA or DNA isolated from 500 sporangia was needed to detect the pathogen. Applications of serological and molecular tools were effective to detect the pathogen in infected symptomatic, asymptomatic potato tissues (Leaves & tubers) and can also provide important information on P. infestans-potato interaction and disease development.