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Research on Dickeya and Pectobacterium

X. Li: Canadian Food Inspection Agency

<div>Species within the genera <em>Dickeya</em> and <em>Pectobacterium</em> cause significant crop losses because they are widespread and pathogenic on a wide variety of plant hosts. In potatoes, <em>Dickeya/Pectobacterium</em> cause blackleg and soft rot diseases which have become increasingly problematic in potato production. While <em>Pectobacterium</em> spp. have been known as causal agents of these diseases in North America since pioneer days, potato blackleg-causing <em>Dickeya</em> spp. were first discovered in the US in 2014. Given the trend in the spread of <em>Dickeya</em> spp. in Europe during the last 15 years, the US and Canada also need to be technically prepared for possible spread of new variants of <em>Pectobacterium</em> and <em>Dickeya</em>, such as <em>D. solani</em>. Although it has never been detected in Canadian crops, <em>D. solani</em> was isolated from hyacinth bulbs imported from Europe highlighting the potential pathway to NA. Comparative genomic analysis using NGS technology revealed differences among <em>Dickeya</em> and <em>Pectobacterium</em> strains congruent with demonstrated variations in pathogenicity and virulence in potato. For instance, an aggressive <em>P. brasiliense</em> subgroups is mostly isolated from potato in tropical regions such as Brazil and South Africa, while a less aggressive subgroup is isolated from potato in temperate regions. The two groups should probably be separated into different subspecies within <em>P. brasiliense</em>, on the basis of virulence associated with three major <em>indels</em> (insertions/deletions) in pathogenicity-related loci. Identification of genetic elements associated with pathogenicity and virulence of the blackleg pathogens has potential for enhancing the differentiation species and subspecies on the basis of their importance in agricultural crops.</div>

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