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POSTERS: New and emerging diseases

Characterization pectolytic bacteria associated with blackleg and soft rot in Pennsylvania potatoes
Amanda Mainello - The Pennsylvania State University. Carolee Bull- The Pennsylvania State University, Beth Gugino- The Pennsylvania State University

Recent outbreaks of potato blackleg and soft rot have resulted in yield loss across the mid-Atlantic due to stem and tuber rot and poor emergence. Surveys were conducted to identify the Pectobacterium spp. and more recently Dickeya spp. associated with these outbreaks. The objective of this study was to characterize select pectolytic isolates from Pennsylvania potatoes exhibiting potato blackleg and soft rot symptoms. Symptomatic plants were collected from Pennsylvania fields in 2016, 2017 and 2018. Pectolytic bacteria were isolated using the selective media, SL-CVP. Isolates were characterized by rep-PCR and 16S rRNA sequence analysis and a few isolates from each year were selected for whole genome sequencing. The phylogenetic relationships between isolates and Dickeya and Pectobacterium spp. type strains were compared using neighbor-joining analyses. Additional analyses using whole genome sequences and multilocus sequences on four housekeeping genes (dnaA, dnaX, dnaJ and gyrB) has been initiated. To date, most isolates have been identified as Pectobacterium carotovorum spp. though other Dickeya spp., namely D. dianthicola, have also been identified. An accurate evaluation of species diversity present in Pennsylvania is crucial for developing effective management methods. This knowledge can be used to elucidate how factors such as cultivar, location, season influence the bacterial species causing blackleg and soft rot.