A Method for the Artificial Inoculation of Potato Tubers with Phytophthora infestans and Polymerase Chain Reaction Assay of Latently Infected Sprouts and Stems

Abstract

This article contains a detailed description of a reliable method for the inoculation of potato tubers with Phytophthora infestans. This technique was developed as a general basic method for greenhouse and field trials to study the development of the primary inoculum source in potato crops. It was applied to increase the reproducibility of infections from tubers to sprouts. Afterwards the pathogen was detected in light sprouts and stems at different stadiums of plant growth by the polymerase chain reaction‐based test (PCR). From this it follows that Phytophthora infestans is able to grow directly up into the stem from the tuber as mycelium. In the course of plant growth the concentration of mycelium fell below the detection limit in some of the assayed stems on account of dilution effects, although the symptoms occurred in the following period. Apparently the pathogen is also able to cause symptoms in the plant at very low concentrations.

Pre and Post Harvest Diseases of Potato and Their Management

“…Latent infection of potato tubers by P. infestans has been implied in development of the disease in Ecuadorian highlands (Kromann et al 2008 ). Latent infection was demonstrated when the pathogen was detected with the aid of polymerase chain reaction (PCR) in asymptomatic tubers (Appel et al 2001 ;Hussain et al 2005 ;Sharma et al 2010 ). Johnson and Cummings ( 2009 ) demonstrated presence of latent infection in seed tubers and production of viable sporangia of P. infestans after cold storage of infected potato tubers.…”

Detection and Identification of Postharvest Microbial Pathogens

“…The concentration of pathogen mycelium was below the detection limit during the course of plant growth, probably due to dilution effects. However, the symptoms induced later indicated the ability of the pathogen to cause symptom at very low concentration (Appel et al, 2001).…”