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2011 APS Annual Meeting Abstract

 

Colonization of tomato seedlings by bioluminescent Clavibacter michiganensis subsp. michiganensis under different humidity regimes
X. XU (1), G. Rajashekara (1), P. A. Paul (1), S. A. Miller (1)
(1) Ohio State University, Wooster, OH, U.S.A.
Phytopathology 101:S195

The dissemination of Clavibacter michiganensis subsp. michiganensis (Cmm), the causal agent of tomato bacterial canker, is facilitated by mechanical wounds that are easily made during seedling production and crop maintenance. Little is known regarding translocation of Cmm in tomato seedlings through wound infection or the influence of environmental factors on Cmm growth as an endophyte. A virulent, stable, constitutively bioluminescent Cmm strain BL-Cmm 17 coupled with an in vivo imaging system (IVIS, Xenogen), a quantitative low-light device, allowed visualization of the Cmm colonization process in tomato seedlings in real-time. The dynamics of bacterial infection in seedlings through wounds were compared under low (45%) and high (83%) relative humidity. Bacteria multiplied rapidly in cotyledon petioles remaining after clip inoculation and moved in the stem towards both root and shoot. Luminescent signals were also observed in tomato seedling roots over time and root development was reduced in inoculated plants maintained under both humidity regimes. Wilting symptom development was more severe in seedlings under high humidity regimes. A strong positive correlation between light intensity with bacterial population in planta suggests that bioluminescent Cmm strains will be useful in evaluating the efficacy of bactericides and host resistance.

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