Poster Session: Bacteriology

24-P

Tomato fruit colonization of Clavibacter michiganensis subsp. michiganensis via external and internal routes.
M. TANCOS (1), C. Smart (1)
(1) Cornell University, Geneva, NY, U.S.A.

Seed-disseminated phytopathogens exemplify the adaptive nature of parasites by successfully gaining access to seed, surviving seed treatment processes, colonizing emergent seedlings, and attaining global distribution. Clavibacter michiganensis subsp. michiganensis (Cmm), the causal agent of bacterial wilt and canker of tomato, continues to induce epidemics throughout all major tomato-producing nations, and insuring healthy seed stock remains a top priority. Understanding the movement of Cmm and its ability to produce systemic infections will help elucidate the mechanisms involved in seed infection. In order to investigate the mode of seed infection, New York Cmm field isolates were stably transformed with eGFP and were used to characterize routes of infection. Preliminary experiments were designed to test the ability of Cmm to access the developing seeds either i) systemically through the xylem and/or ii) externally by entering fruit through lesions on the pericarp. The use of laser scanning confocal microscopy and in planta colonization studies confirmed that the transformants continued to express eGFP while infecting tomato plants; and Cmm was able to successfully invade the fruit tissue, thereby, highlighting the multifaceted infective nature of Cmm. These studies will increase our understanding of the adaptive nature of Gram-positive bacteria and the mechanisms utilized during seed infection.