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Poster: Diseases of Plants: Disease Detection & Diagnosis


Identification of the causal agents of soft rot of potato in Bangladesh and activity of biocontrol agents against the pathogens
F. ELAHI (1) (1) The Ohio state University, U.S.A.

Potato is a staple food crop in Bangladesh. Bacterial soft rot is a major postharvest threat to potato, reducing yield approximately 37% in storage systems. Limited research has been conducted to identify and manage the causal agents of soft rot in Bangladesh. Eighteen bacterial isolates were collected from twelve potato-growing regions of Bangladesh in 2015. Sixteen of the isolates produced deep pits on Crystal-Violet Pectate (CVP) medium, were gram negative, oxidase negative, and hypersensitive response (HR) positive on tobacco, characteristic of Pectobacterium. Two isolates produced shallow pits on CVP medium, were gram negative, oxidase positive, fluorescent, and weakly HR positive, characteristic of Pseudomonas. All isolates caused soft rot on potato tubers. Partial 16s ribosomal DNA sequences from 16 presumptive Pectobacterium isolates exhibited >85% identity with Pectobacterium ssp. sequences and two presumptive Pseudomonas isolates exhibited 90% identity with P. fluorescens and P. putida sequences previously deposited in GenBank. Fifteen Pseudomonas sp. strains with known biocontrol activity were tested for in vitro antibiosis against the soft rotting isolates. The biocontrol agents inhibited the growth of all Pectobacterium isolates but neither of the Pseudomonas isolates. Biological control of potato soft rot by Pseudomonas spp. is promising but additional research is needed to identify potential biocontrol agents for soft rotting Pseudomonas spp.