New PCR-Based Assay for the Identification of Causing Potato Soft Rot.

Soft rot on potato tuber is a destructive disease caused by pathogenic bacterial species of the genera and . Accurate identification of the causal agent is necessary to ensure adequate disease management because different species may have distinct levels of aggressiveness and host range. One of the most important potato pathogens is , a highly heterogeneous species capable of infecting multiple hosts. The complexity of this species, until recently divided into several subspecies, has made it difficult to develop precise diagnostic tests. This study proposes a PCR assay based on the new pair of primers Pcar1F/R to facilitate the identification of potato isolates of according to the most recent taxonomic description of this species. The new primers were designed on a variable segment of the 16S rRNA gene and the intergenic spacer region of available DNA sequences from classical and recently established species in the genus . The results of the PCR analysis of genomic DNA from 32 and strains confirmed that the Pcar1F/R primers have sufficient nucleotide differences to discriminate between and other species associated with damage to potato crops, with the exception of , which improves the specificity of the currently available primers. The proposed assay was originally developed as a conventional PCR but was later adapted to the real-time PCR format for application in combination with the existing real-time PCR test for the potato-specific pathogen This should be useful for the routine diagnosis of potato soft rot.