Location: Floral and Nursery Plants Research
Project Number: 8020-22000-042-009-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 30, 2018
End Date: Aug 31, 2020
Objective 1: Identify genomic regions/genes that are unique in cool tolerant strains of Ralstonia solanacearum. Objective 2: Identify host targets for Ralstonia solanacearum type III effectors.
Because of historical evidence of ability to survive and kill solanaceous crops under cool climate conditions, Ralstonia solanacearum Race 3 Biovar 2 (R3B2) is designated as a “Select Agent” under the Agricultural Bioterrorism Protection Act of 2002. With agricultural globalization, the threat of introduction into the U.S. has increased. In addition to R3B2 strains, ARS has identified other cool tolerant bacterial wilt strains that have become established in the U.S. These strains possess similar genetic components found in R3B2 strains and have the potential to survive and infect tomato and potato plants at low temperatures and threaten U.S. agriculture. It is thus important to determine the potential environmental source and movement of these populations of Ralstonia within the U.S. In order to make prudent decisions on regulation and to mitigate potential losses, a better understanding of the biology of the cool tolerant bacterial wilt strains is needed. An empirical approach will be used to examine the genetic and physiological capability of cool-tolerant strains of bacterial wilt to assess their ability to become established and spread within temperate climates found in the U.S. Using a proteomics approach ARS has identified 112 proteins involved in virulence of cool-tolerant strains. The function of proteins involved in the colonization and invasion of the rhizosphere will be determined. Utilizing gene knock-out techniques and total genome sequencing of select strains, specific genes associated with cool virulence will be identified, giving a better understanding of infection mechanism(s) and ultimately control. Using a Y2H library made from Solanaum lycopersicon with Ralstonia effectors, targets for some of these effectors will be identified. These interactions will be confirmed using Co-Immunoprecipitation and Biomolecular fluorescence complementation. To determine functional significance of the interaction of Ralstonia effectors with their host targets, loss-of-function approaches and Virus Induced Gene Silencing will be utilized in Nicotiana benthamiana and S. lycopersicon as model systems. Results of these experiments will lead to molecular insights into how Ralstonia infects plant cells and will assist in devising novel disease management strategies.