Surviving the potato stems: differences in genes required for fitness by Dickeya dadantii and Dickeya dianthicola

Authors: GONZALEZ-TOBON, JULIANA - Cornell University; HELMANN, TYLER - Former ARS Employee; Stodghill, Paul; Filiatrault, Melanie

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/23/2023
Publication Date: 5/20/2024
Citation: Gonzalez-Tobon, J., Helmann, T., Stodghill, P., Filiatrault, M.J. 2024. Surviving the potato stems: differences in genes required for fitness by Dickeya dadantii and Dickeya dianthicola. Phytopathology. 114:1106-1117. https://doi.org/10.1094/PHYTO-09-23-0351-KC.
DOI: https://doi.org/10.1094/PHYTO-09-23-0351-KC

Interpretive Summary: Plant pathogenic bacteria such as Dickeya cause disease in various important crops including potato. There are still considerable gaps in our knowledge of the bacterial factors that allow specific Dickeya species to be successful plant colonizers and what genes are critical for survival in potato plants. In this study, bacteria with barcoded transposon insertions were inoculated into potato stems to identify genes that contribute to bacterial fitness during the development of stem rot. Our unique approach identified genes not previously described as having roles in host colonization and/or survival in potato stems. By comparing the results of two different Dickeya species, we identified shared genes important for growth in potato stems. This research provides insight into the mechanisms soft rot pathogens use to cause disease and provides targets for disease management.

Technical Abstract: Bacteria belonging to the Dickeya genus cause blackleg and soft rot symptoms on many plant hosts, including potato. Although there is considerable knowledge about the genetic determinants that allow Dickeya to colonize host plants, as well as the genes that contribute to virulence, much is still unknown. To identify the genes important for fitness in potato stems, we constructed and evaluated randomly barcoded transposon mutant (RB-TnSeq) libraries of Dickeya dadantii and Dickeya dianthicola. We identified 169 and 157 genes important for growth in D. dadantii and D. dianthicola in stems, respectively. This included gene related to metabolic pathways, chemotaxis and motility, transcriptional regulation, transport across membranes, membrane biogenesis, detoxification mechanisms, and virulence-related genes including a potential virulence cluster srfABC, c-di-GMP modulating genes, and pectin degradation genes. Comparing the results of the stem assay with other datasets, we identified genes important for growth in stems versus tubers and in vitro conditions. Additionally, our data showed that there are some differences in fitness determinants for D. dadantii and D. dianthicola. This data provides important insights into the mechanisms used by Dickeya when interacting with and colonizing plants, and thus might provide targets for management.