Isolation, identification, and characterization of Pectobacterium actinidiae isolated from infected sugar beet leaves

Abstract

AbstractDuring the sugar beet growing seasons of 2019 and 2020, symptomatic leaf samples displaying necrotic spots were collected for the isolation of pectinolytic bacteria. Seven bacterial isolates were obtained from these infected leaves on crystal violet pectate (CVP) medium. Two of these isolates exhibited the ability to macerate potato tuber slices and induced disease symptoms on petioles of sugar beet plants. Initially, their identity was determined to be Pectobacterium spp. through a polymerase chain reaction (PCR) that produced a 434 bp amplicon using Y1/Y2 primers. Subsequently, they generated a 550 bp PCR product with the EXPCCF/EXPCCR primers, classifying them as P. carotovorum. Further analysis of both strains involved the examination of the dnaX and mdh genes to confirm their taxonomic status. BLASTn analysis revealed the highest sequence similarity with P. actinidiae strains in GenBank for dnaX (99.39%–100%) and mdh (100%) genes. Phylogenetic analysis, based on sequences from dnaX, mdh, and a concatenation of both genes, conducted alongside 21 species of Pectobacterium spp., unequivocally confirmed that strains Pact1 and Pact2 belong to P. actinidiae. This study marks the first‐ever report of the presence of P. actinidiae in sugar beet worldwide.