Title: The Subcellular Localization of Ralstonia solanacearum K60 Type III Effectors

Ralstonia solanacearum is a soil-borne bacterial pathogen that causes Bacterial Wilt disease in over 200 plant species in 53 botanical families (Genin 2010). This detrimental disease is found globally and is caused by various strains of R. solanacearum; one example is the K60 strain which is found in the United States. Bacterial pathogens like R. solanacearum use their type III secretion system (T3SS) to suppress host immune responses and cause disease. T3SS is composed of a needle-like structure that pierces the host cell wall and secretes type III effector (T3E) proteins into the host cell. The function of the T3Es in the K60 strain is not well understood. A small list of K60 T3E proteins was selected to be studied; the first step in this experiment is to determine the subcellular localization of these T3Es. A green fluorescent protein (GFP) was attached to the C-terminus of the individual T3E, and was transiently expressed in two systems: the hairy root system in tomato and the Nicotiana benthamiana leaf system. The subcellular localization of each T3E was observed with the Zeiss LSM 880 Upright Confocal Microscope. Preliminary results suggest that two T3Es, RsK60-8 and RsK60-17, localize at the plasma membrane, RsK60-15 at the nucleus, and two, RsK60-3 and RsK60-6, localize at actin filaments. Future work will use secretion assays to confirm secretion of the T3Es, as well as yeast two-hybrid and mutant analyses to determine the interacting partners and function of the individual T3Es.