Spatial Organization of Dual-Species Bacterial Aggregates on Leaf Surfaces
Open Access
- 1 September 2005
- journal article
- Published by American Society for Microbiology in Applied and Environmental Microbiology
- Vol. 71 (9), 5484-5493
- https://doi.org/10.1128/aem.71.9.5484-5493.2005
Abstract
The spatial organization of cells within bacterial aggregates on leaf surfaces was determined for pair-wise mixtures of three different bacterial species commonly found on leaves, Pseudomonas syringae , Pantoea agglomerans , and Pseudomonas fluorescens . Cells were coinoculated onto bean plants and allowed to grow under moist conditions, and the resulting aggregates were examined in situ by epifluorescence microscopy. Each bacterial strain could be localized because it expressed either the green or the cyan fluorescent protein constitutively, and the viability of individual cells was assessed by propidium iodide staining. Each pair of bacterial strains that was coinoculated onto leaves formed mixed aggregates. The degree of segregation of cells in mixed aggregates differed between the different coinoculated pairs of strains and was higher in mixtures of P. fluorescens A506 and P. agglomerans 299R and mixtures of P. syringae B728a and P. agglomerans 299R than in mixtures of two isogenic strains of P. agglomerans 299R. The fractions of the total cell population that were dead in mixed and monospecific aggregates of a gfp -marked strain of P. agglomerans 299R and a cfp -marked strain of P. agglomerans 299R, or of P. fluorescens A506 and P. agglomerans 299R, were similar. However, the proportion of dead cells in mixed aggregates of P. syringae B728a and P. agglomerans 299R was significantly higher (13.2% ± 8.2%) than that in monospecific aggregates of these two strains (1.6% ± 0.7%), and it increased over time. While dead cells in such mixed aggregates were preferentially found at the interface between clusters of cells of these strains, cells of these two strains located at the interface did not exhibit equal probabilities of mortality. After 9 days of incubation, about 77% of the P. agglomerans 299R cells located at the interface were dead, while only about 24% of the P. syringae B728a cells were dead. The relevance of our results to understanding bacterial interactions on leaf surfaces and the implications for biological control of pathogenic and other deleterious microorganisms is discussed.Keywords
This publication has 23 references indexed in Scilit:
- Frequency, Size, and Localization of Bacterial Aggregates on Bean Leaf SurfacesApplied and Environmental Microbiology, 2004
- Pseudomonas syringae Responds to the Environment on Leaves by Cell Size ReductionPhytopathology®, 2003
- Quorum sensing controls the synthesis of virulence factors by modulating rsmA gene expression in Erwinia carotovora subsp. carotovoraMolecular Genetics and Genomics, 2001
- Endophytic Colonization of Plants by the Biocontrol Agent Rhizobium etli G12 in Relation to Meloidogyne incognita InfectionPhytopathology®, 2001
- The Involvement of Cell-to-Cell Signals in the Development of a Bacterial BiofilmScience, 1998
- Environmental Signals Modulate the Expression of an Indole-3-Acetic Acid Biosynthetic Gene in Erwinia herbicolaMolecular Plant-Microbe Interactions®, 1997
- Dose-Response Relationships and Inundative Biological ControlPhytopathology®, 1994
- Biological Control in the PhyllosphereAnnual Review of Phytopathology, 1992
- Role of Antibiosis in the Biocontrol of Plant Diseases*Annual Review of Phytopathology, 1988
- Lack of Evidence for In Situ Fluorescent Pigment Production byPseudomonas syringaepv.syringaeon Bean Leaf SurfacesPhytopathology®, 1987