Development of SCAR primers for the detection of the postharvest pathogens of kiwifruit and pome fruit Cadophora luteo-olivacea and C. malorum

Abstract

In recent years a postharvest disease of kiwifruit, characterized by skin pitting appearing after 3 or more months of storage, and caused by C. luteo-olivacea, has been reported in most Italian packinghouses. Forty-four strains isolated from kiwifruit harvested in Italy during the period 2001-2009 were tested for their pathogenicity on kiwifruit, apple and pear. The pathogenicity tests showed that different isolates of C. luteo-olivacea were pathogenic on the three fruit species stored at 1°C for 120 days with various degree of virulence. A PCR-based method to identify the pathogen species in kiwifruit was developed. Sequencing of the internal transcribed spacer (ITS1, 5.8S gene and ITS2) region of the rDNA (ITS) showed high similarity with the species C. malorum, agent of side rot of apples and pears. Variation within the ITS was used to design one reverse primer common to both species and two species specific forward primers to specifically identify isolates of C. luteo-olivacea and C. malorum. Both SCAR (sequence characterized amplified region) primer pairs showed to be specific for either Cadophora species when cross-tested and assessed on other species of Cadophora or on species of typical postharvest pathogens of kiwifruit, apple and pear.