Spatially-explicit depiction of a floral epiphytic bacterial community reveals role for environmental filtering within petals

The microbiome of flowers (anthosphere) is an understudied compartment of the plant microbiome. Within the flower, petals represent a heterogeneous environment for microbes in terms of resources and environmental stress. Yet little is known of drivers of structure and function of the epiphytic microbial community at the within-petal scale. We characterized the petal microbiome in two co-flowering plants that differ in pattern of ultraviolet (UV) absorption along their petals. Bacterial communities were similar between plant hosts, with only rare phylogenetically distant species contributing to differences. The epiphyte community was highly culturable (75% of families) lending confidence to the spatially-explicit isolation and characterization of bacteria. In one host, petals were heterogeneous in UV absorption along their length and in these there was a negative relationship between growth rate and position on the petal, as well as lower UV tolerance in strains isolated from the UV absorbing base than from UV reflecting tip. A similar pattern was not seen in microbes isolated from a second host whose petals had uniform patterning along their length. Across strains, variation in carbon utilization and chemical tolerance followed common phylogenetic patterns. This work highlights the value of petals for spatially-explicit explorations of bacteria of the anthosphere.

Methods
For methodological details please consult the paper: Hayes et al. (2020). Spatially-explicit depiction of a floral epiphytic bacterial community reveals role for environmental filtering within petals. MicrobiologyOpen. If there are still doubts, please email Maria Rebolleda-Gomez at <mariarebolleda at gmail dot com>.