First Report of Pectobacterium brasiliense Causing Bitter Melon Soft Rot Disease in Korea

Abstract

In the Goesan region, located in Chungcheongbuk-do, Korea, a significant outbreak of soft rot infections was documented in August 2021, affecting fruits of <i>Momordica charantia</i>, commonly known as bitter melon or bitter gourd. The symptoms included a noticeable transition to yellowing in the affected fruits, eventually leading to their collapse. The bacterial strain KNUB-09-21 was isolated from the diseased fruits. Molecular analysis, using the sequences of the 16S rRNA region and three housekeeping genes (<i>dnaX, recA</i>, and <i>leuS</i>), along with the results of compound utilization in the API ID 32 GN system, provide strong evidence for the identification of the isolate KNUB-09-21 as <i>Pectobacterium brasiliense</i>. The pathogenicity of strain KNUB-09-21 on <i>M. charantia</i> was confirmed through a controlled inoculation test. Within two days, inoculated fruits displayed soft rot symptoms closely resembling those observed in naturally affected fruits. This is the first report of soft rot on <i>M. charantia</i> in Korea.