Influence of native plasmids to fitness of Pantoea vagans strain C9-1

Authors: KLEIN, J - Oregon State University; STOCKWELL, V - Oregon State University; Loper, Joyce

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 6/3/2015
Publication Date: 11/1/2015
Citation: Klein, J.M., Stockwell, V.O., Loper, J.E. 2015. Influence of native plasmids to fitness of Pantoea vagans strain C9-1 [abstract]. Phytopathology. 105:54-73.

Interpretive Summary:

Technical Abstract: Pantoea vagans strain C9-1 is a biological control agent for fire blight caused by Erwinia amylovora. We cured C9-1 of two of its three plasmids: pPag2, pPag3, and both pPag2 and pPag3, tested phenotypes of the derivatives, and evaluated blossom colonization in the field. pPag2 (166 kb) encodes for production of the antibiotic herbicolin I and tellurite resistance. We found that C9-1 lacking pPag2 were more sensitive to tellurite than C9-1. pPag3 (530 kb) carries genes for a carotenoid pigment, thiamine biosynthesis, iron acquisition, and UV tolerance. C9-1 lacking pPag3 formed white colonies, were thiamine auxotrophs, and produced smaller zones on CAS agar compared to the wild type C9-1. UV-tolerance did not differ between C9-1 and its derivatives lacking pPag3. Swarming patterns on nutrient broth-glucose solidified with 0.5% agar were influenced by pPag3. C9-1 formed wide dendritic swarms that coalesced, whereas C9-1 lacking pPag3 formed thin dendritic swarms. Biofilm formation was greater with derivatives lacking both pPag2 and pPag3 compared to the wild type. In an orchard trial, C9-1 and derivatives cured of pPag2 and/or pPag3 established similar population sizes on apple blossoms. Although some of the assayed phenotypes were negatively affected by the loss of one or two plasmids, the epiphytic fitness of C9-1 in orchards was not reduced by plasmid loss