Transcriptional Response of Pectobacterium carotovorum to Cinnamaldehyde Treatment.

Cinnamaldehyde is a natural compound extracted from cinnamon bark essential oil, acclaimed for its versatile properties in both pharmaceutical and agricultural fields, including antimicrobial, antioxidant, and anticancer activities. Although potential of cinnamaldehyde against plant pathogenic bacteria like Agrobacterium tumefaciens and Pseudomonas syringae pv. actinidiae causative agents of crown gall and bacterial canker diseases, respectively has been documented, indepth studies into cinnamaldehyde's broader influence on plant pathogenic bacteria are relatively unexplored. Particularly, Pectobacterium spp., gram-negative soil-borne pathogens, notoriously cause soft rot damage across a spectrum of plant families, emphasizing the urgency for effective treatments. Our investigation established that the Minimum Inhibitory Concentrations (MICs) of cinnamaldehyde against strains P. odoriferum JK2, P. carotovorum BP201601, and P. versatile MYP201603 were 250 µg/ml, 125 µg/ml, and 125 µg/ml, respectively. Concurrently, their Minimum Bactericidal Concentrations (MBCs) were found to be 500 µg/ml, 250 µg/ml, and 500 µg/ml, respectively. Using RNA-sequencing analysis, we identified 1,907 differentially expressed genes in P. carotovorum BP201601 treated with 500 µg/ml cinnamaldehyde. Notably, our results indicate that cinnamaldehyde upregulated nitrate reductase pathways while downregulating the citrate cycle, suggesting a potential disruption in the aerobic respiration system of P. carotovorum during cinnamaldehyde exposure. This study serves as a pioneering exploration of the transcriptional response of P. carotovorum to cinnamaldehyde, providing insights into the bactericidal mechanisms employed by cinnamaldehyde against this bacterium.

A New Approach Using the SYBR Green-Based Real-Time PCR Method for Detection of Soft Rot Pectobacterium odoriferum Associated with Kimchi Cabbage.

Pectobacterium odoriferum is the primary causative agent in Kimchi cabbage soft-rot diseases. The pathogenic bacteria Pectobacterium genera are responsible for significant yield losses in crops. However, P. odoriferum shares a vast range of hosts with P. carotovorum, P. versatile, and P. brasiliense, and has similar biochemical, phenotypic, and genetic characteristics to these species. Therefore, it is essential to develop a P. odoriferum- specific diagnostic method for soft-rot disease because of the complicated diagnostic process and management as described above. Therefore, in this study, to select P. odoriferum-specific genes, species-specific genes were selected using the data of the P. odoriferum JK2.1 whole genome and similar bacterial species registered with NCBI. Thereafter, the specificity of the selected gene was tested through blast analysis. We identified novel species-specific genes to detect and quantify targeted P. odoriferum and designed specific primer sets targeting HAD family hydrolases. It was confirmed that the selected primer set formed a specific amplicon of 360 bp only in the DNA of P. odoriferum using 29 Pectobacterium species and related species. Furthermore, the population density of P. odoriferum can be estimated without genomic DNA extraction through SYBR Green-based real-time quantitative PCR using a primer set in plants. As a result, the newly developed diagnostic method enables rapid and accurate diagnosis and continuous monitoring of soft-rot disease in Kimchi cabbage without additional procedures from the plant tissue.