Two-way microscale interactions between immigrant bacteria and plant leaf microbiota as revealed by live imaging

Abstract

The phyllosphere -the aerial parts of plants -is an important microbial habitat that is home to diverse microbial communities. The spatial organization of bacterial cells on leaf surfaces is non-random and correlates with leaf microscopic features. Yet the role of microscale interactions between cells therein is not well-understood. Here, we ask how interactions between immigrant bacteria and resident microbiota affect the spatial organization of the combined population. By means of live imaging on a simplified in vitro system, we studied the microscale spatial organization of the plant pathogen Pseudomonas syringae B728a and the bio-control agent P. fluorescens A506 when introduced to both native and non-native leaf microbiota (bean and pear). We revealed that both strains preferentially attach to the surface in locations adjacent to microbiota aggregates. Interestingly, preferential attachment of microbiota cells near newly formed P. fluorescens aggregates was also observed. Our results indicate that twoway immigrant bacteria -resident microbiota interactions affect the microscale spatial organization of leaf microbial communities; and that preferential attachmentpreviously suggested as a general strategy that increases fitness under periodic stressis a common surface colonization strategy. The implications of this study are likely relevant to other surface-associated microbial habitats. DiscussionIn summary, through live imaging and spatial analyses at microscale, we show that immigrant bacteria display a non-random spatial colonization pattern with respect to the spatial organization of natural resident leaf microbiota cells. This non-random organization is not necessarily observable by eye, but was revealed by a rigorous image and spatial analysis. As our simplified system excludes the heterogeneity of

Bacterial survival in microscopic surface wetness

“…Thus, our single-strain experiments, with M9 medium on glass-bottom wells, may not capture survival strategies that might be triggered by environmental cues and that rely on other members of the community. For example, joining existing aggregates of other species can be a beneficial strategy in environments with recurrent drying events (Grinberg et al, 2019; Steinberg et al, 2019).…”

Spatially resolved correlative microscopy and microbial identification reveal dynamic depth‐ and mineral‐dependent anabolic activity in salt marsh sediment

“…burial process in which a given horizon's community represents the confluence of local selective pressures operating on an assemblage of organisms 'imported' from above or from below due to tidal pumping. At each of the three horizons examined through correlative microscopy, cells appeared to be distributed not as evenly spaced individual cells, but rather as aggregations suggestive of inter-organism interactions consistent with a 'sphere of influence' on the order of a few microns (Dal Co et al, 2020;Steinberg et al, 2021) (Figs 3-5). Throughout the sediment column, quartz was the dominant mineral type, yet microbial communities associated with quartz grains had the lowest proportion of anabolically active members.…”

Metabolic resource overlap impacts on the competition of phyllosphere bacteria

“…For bacteria, the phyllosphere -mostly represented by leaf surfaces-constitutes a challenging environment where resources are limited and heterogeneously distributed (1,2). This fragmented microbial habitat promotes cell-to-cell contact and should directly impact on community dynamics by short-distance interactions (1,(3)(4)(5), leading to the local competition for resources and spatial structuring of bacterial communities (6)(7)(8). Resource competition results in either exclusion or coexistence depending on the strength of interspecies interactions in relation to conspecific interactions, that is, interactions within a species (9).…”