GENETIC INSIGHT INTO THE ISOLATES CAUSING BLACKLEG DISEASE ON POTATO

Abstract

Blackleg disease, caused by pectolytic bacteria from genus Dickeya and Pectobacterium is currently being one of the main concerns in potato production. Yield loss and reduced quality, visible through potato black rotting at the stem base, as well as whole plant decaying, makes potato cultivation less profitable. Blackleg disease outbreak was observed in potato field (cv. Lady Claire) in Bačka (northern Serbia) in June 2018. The percent of the infected plants, estimated during the vegetation season was 45%, with yield reduction of about 20%. In this study the causal pathogens were genetically characterized using multilocus sequence analysis (MLSA). DNA of the obtained isolates was amplified with primers made based on the sequences of five housekeeping genes - gapA, icdA, mdh, pgi and proA and sequenced. Phylogenetic analysis was performed to compare the obtained isolates with the ones already deposited in NCBI database. NCBI BLAST identified isolates as Dickeya dianthicola and Pectobacterium carotovorum subsp. brasiliensis, indicating on the persistence of mix infection on observed potato crop. According to all genes, isolates appeared to be the most similar (99-100%) to the reference strains - D. dianthicola (CFBP 1200) and P. carotovorum subsp. brasiliensis (BC1). Blast results were confirmed after phylogenetic analysis, where isolates of both identified species were clustering with the rest of the strains of the same species, obtained from NCBI. Our findings confirm the presence of new blackleg causal agents, D. dianthicola and P. carotovorum subsp. brasiliensis on potato in Serbia. Their isolation and localization is of great importance, especially D. dianthicola which has quarantine status, and therefore it gives a signal for pathogen eradication and prevention of its future spreading.