Species-specific detection of Dickeya sp. (Pectobacterium chrysanthemi) in infected banana tissues, soil and water

Abstract

Dickeya sp. (Pectobacterium chrysanthemi) is a bacterial pathogen that can cause soft rot disease on banana pseudostem tissue. A species-specific polymerase chain reaction (PCR) assay was developed for rapid and sensitive detection of the pathogenic bacteria in diseased plant tissues, soil and artificially infested irrigation water. Based on differences in internal transcribed spacer (ITS) sequences of Dickeya sp. (P. chrysanthemi) and other bacteria, a pair of species-specific primers was synthesized. Specificity was tested against eight bacterial organisms associated with banana. The LF/LR primers amplified only a single PCR band of 171 bp from Dickeya sp. (P. chrysanthemi). The detection sensitivity was determined to be 0.44 fg for pure genomic DNA per 25 μl reaction volume. The results suggest that the assay detected the pathogen more rapidly and accurately than standard isolation methods. The PCR-based methods developed here could simplify both plant disease diagnosis and pathogen monitoring, as well as guide plant disease management.

Key words: Soft rot, banana, detection, polymerase chain reaction (PCR).