Occurrence of Bacterial Stem Rot of Ranunculus asiaticus Caused by Pseudomonas marginalis in Korea

Abstract

In December 2016, stem rot symptoms were observed on Persian buttercup (Ranunculus asiaticus) plants in Chilgok, Gyeongbuk, Korea. In the early stage of the disease, several black spots appeared on the stem of infected plants. As the disease progressed, the infected stem cleaved and wilted. The causal agent was isolated from a lesion and incubated on Reasoner's 2A (R2A) agar at 25°C. Total genomic DNA was extracted for phylogenetic analysis. Based on the 16S rRNA gene analysis, the isolated strain was found to belong to the genus Pseudomonas. To identify the isolated bacterial strain at the species level, the nucleotide sequences of the gyrase B (gyrB) and RNA polymerase D (rpoD) genes were obtained and compared with the sequences in the GenBank database. As the result, the causal agent of the stem rot disease was identified as Pseudomonas marginalis. To determine the pathogenicity of the isolated bacterial strain, it was inoculated into the stem of healthy R. asiaticus plant, the inoculated plant showed a lesion with the same characteristics as the naturally infected plant. Based on these results, this is the first report of bacterial stem rot on R. asiaticus caused by P. marginalis in Korea.

Keywords

• Bacterial disease
• Pseudomonas marginalis
• Ranunculus spp.