title: Colonization of tomato seedlings by bioluminescent Clavibacter michiganensis subsp. michiganensis under different humidity regimes.
abstract: Tomato bacterial canker, caused by Clavibacter michiganensis subsp. michiganensis, is transmitted by infected or infested seed and mechanically from plant to plant. Wounds occurring during seedling production and crop maintenance facilitate the dissemination of the pathogen. However, the effects of environmental factors on C. michiganensis subsp. michiganensis translocation and growth as an endophyte have not been fully elucidated. A virulent, stable, constitutively bioluminescent C. michiganensis subsp. michiganensis strain BL-Cmm 17 coupled with an in vivo imaging system allowed visualization of the C. michiganensis subsp. michiganensis 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 toward 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 was more severe in seedlings under high-humidity regimes. A strong positive correlation between light intensity and bacterial population in planta suggests that bioluminescent C. michiganensis subsp. michiganensis strains will be useful in evaluating the efficacy of bactericides and host resistance.
authors.affiliation: Department of Plant Pathology, The Ohio State University, Ohio Agricultural Research and Development Center, Wooster, Ohio 44691, USA.
authors.forename: Xiulan
authors.initials: X
authors.lastname: Xu
authors.forename: Gireesh
authors.initials: G
authors.lastname: Rajashekara
authors.forename: Pierce A
authors.initials: PA
authors.lastname: Paul
authors.forename: Sally A
authors.initials: SA
authors.lastname: Miller
mesh_terms: D000192:Actinomycetales / Q000254:growth & development / Q000502:physiology* / Q000528:radiation effects; D018548:Cotyledon / Q000382:microbiology; D006813:Humidity; D008027:Light; D008163:Luminescent Measurements / Q000379:methods; D008164:Luminescent Proteins / Q000378:metabolism; D018551:Solanum lycopersicum / Q000382:microbiology* / Q000528:radiation effects; D010935:Plant Diseases / Q000382:microbiology*; D057865:Plant Immunity; D018515:Plant Leaves / Q000382:microbiology; D018517:Plant Roots / Q000382:microbiology; D018547:Plant Stems / Q000382:microbiology; D036226:Seedlings / Q000382:microbiology*; D013997:Time Factors
chemical_list: D008164:Luminescent Proteins