Detection of Phytophthora erythroseptica in Above-ground Potato Tissues, Progeny Tubers, Stolons and Crop Debris Using PCR Techniques

Abstract

Pink rot of potatoes caused by Phytophthora erythroseptica is known to infect all underground potato (Solanum tuberosum) tissues such as roots, stolons, tubers and basal stems. Potato leaves and stems do not normally exhibit symptoms except when extensive infection of underground plant parts results in plant wilt, chlorosis and necrosis. This is the first study to investigate the spread of P. erythroseptica in above-ground potato tissues using both traditional isolation and PCR methods originally developed to detect the pathogen in tubers. P. erythroseptica was detected in 66% of leaf and stem tissue samples originated from artificially-inoculated and naturally-infected tubers of ‘Yukon Gold’ and ‘Shepody’ by PCR methods. However, it was only recovered in pure cultures from 38% of stem and leaf tissue samples. The pathogen was also detected in leaf and stem tissues and aerial tubers of plantlets grown in potting mixtures infested with P. erythroseptica. Pure cultures of P. erythroseptica obtained from stem and leaf tissues, together with the 95% of the detection with the real-time PCR assay and 45% with the conventional PCR assay confirmed the viability of the pathogen in above-ground potato tissues. Furthermore, the pathogen was detected in progeny tubers and stolons produced by the infected potato plants. P. erythroseptica was also detected in a few samples of debris taken from naturally senesced above-ground potato tissue after harvest.