P-477 - RNAi as an integrated pest management strategy for emerging species of Neopestalotiopsis

Strawberry (Fragaria x ananassa Duch.) is susceptible to a wide range of pathogens, causing severe disease and crop loss. Recently, an outbreak caused by a new aggressive species of Neopestalotiopsis was identified in Florida that caused catastrophic losses. Currently, there are very few management options available for this pathogen. A three-year survey was completed in Ontario to monitor epidemiology of the aggressive species of Neopestalotiopsis. Of the 45 symptomatic samples collected over a three-year period, 42% tested positive for three distinct species within the Neopestalotiopsis genus. The aggressive species represented 81% of the positive samples and 6% and 13% were identified as less aggressive N. rosae and a new undescribed species, respectively. A cleaved amplified polymorphism sequence (CAPS) assay with high sensitivity and specificity was designed to differentiate between the aggressive species and the non-aggressive species.  To explore interfering RNA as a biofungicide, a 415 bp region of the β-tubulin gene of a related fungal species was tested against the three Neopestalotiopsis species.  The partial β-tubulin inhibited mycelia growth of the aggressive species of Neopestalotiopsis by 40-60%.  The β-tubulin is a highly conserved gene, and it’s use in RNAi shows effectiveness but highlights specificity requirements to ensure minimal cross reactivity across genera and species.  These results indicate that RNAi may provide an environmentally friendly cost-effective integrated pest management strategy for emerging pathogens.