Co-occurrence of latent Dickeya and Pectobacterium species in potato seed tuber samples from northern Finland

Yeshitila Degefu

doi:10.23986/afsci.101446

Abstract

Recent methodological developments have uncovered the etiological diversity of the potato blackleg and soft rot Pectobacteriaceae. At least five species in the genera Dickeya and Pectobacterium have been confirmed to cause blackleg on potatoes in Finland. The bacteria are seed borne and remain latent in the tuber until conditions favourable for growth, multiplication and infection prevail. Tubers could be infected by one or more of these species. This short communication is based on the results of molecular detection data collected for more than 14 years from potato seed lots produced in Finland. Diagnostic PCR assay specific to Dickeya solani, Pectobacterium atrosepticum, Pectobacterium carotovorum, P. brasiliense and P. parmentieri revealed that potatoes are infected by one or more of these species; it also revealed that single species infection is more common than multiple colonization. An event of simultaneous occurrences of different strains from the Pectobacterium species appears to be more frequent than that observed between Dickeya and Pectobacterium species. The absence of co-occurrence of Dickeya solani and Pectobacterium atrosepticum is intriguing.

Highlights

The enterobacteria in the genera Dickeya and Pectobacterium belonging to the recently established Pectobacteriaceae family (Adeolu et al 2016) are the primary causes of blackleg and soft rot on potatoes
Fourteen years (2004–2018) of polymerase chain reaction (PCR)-based detection and diagnosis of latent soft rot and blackleg enterobacteria, namely Dickeya and Pectobacterium spp. in seed potatoes cultivated in Finland, revealed that potatoes are infected by one or more species of the bacteria
The results demonstrated that single species infection is more common (82% of samples) than multiple species or co-infection (Table 3)

Summary

Introduction

The enterobacteria in the genera Dickeya and Pectobacterium belonging to the recently established Pectobacteriaceae family (Adeolu et al 2016) are the primary causes of blackleg and soft rot on potatoes. The taxonomy of Dickeya and Pectobacterium has undergone significant revision in recent years This includes the establishment of new species and transfer of strains to new species (Samson et al 2005, Pasanen et al 2013, van der Wolf et al 2014, Khay et al 2016, Dees et al 2017, Motyka et al 2017, Portier et al 2020). The observed etiological diversity causes diagnostic complexity and increases the cost of laboratory seed testing. Since these species cause symptoms on potatoes indistinguishable from each other, visual inspection as a method of seed certification and pathogen identification is currently not reliable

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