Investigation of Potassium Tetraborate Resistance in Dickeya spp.

Abstract

Dickeya spp. are common plant pathogens associated with bacterial soft rot, potato blackleg, and slow wilt, which are plant diseases that account for major losses in the agricultural industry. The diseases caused by these bacterial species are not yet fully managed with existing techniques, and new approaches need to be considered to minimize future crop loss. Previous research has shown that the inorganic salt potassium tetraborate tetrahydrate (PTB) can inhibit the growth of Dickeya species; however, disk diffusion assays result in a unique phenotype with two zones of inhibition. This study investigates the effects of PTB on the growth of four Dickeya spp.. It was hypothesized that the production of phage is responsible for the two zones of inhibition. Disk diffusion assays and growth curves were used to confirm the impact of PTB on Dickeya and attempts were made to directly isolate phage from the strains. To elucidate the mechanism of action of PTB, Tn-Seq libraries were used to determine which genes are required for growth in the presence of PTB. Tn-Seq libraries showed that different Dickeya strains shared seven overlapping genes including stress-related genes that increase bacterial resistance to PTB. Gene expression studies were used to determine the changes in gene expression that result from PTB exposure. Preliminary results showed that exposure to PTB induces the expression of stress-related genes in Dickeya to increase survival in the presence of the compound. Further research is needed to better understand the implications of observed changes in bacterial gene expression.