Bacteria associated with flowers affect the reproductive success ofBrassica napusL.viascent-mediated interactions with pollinators

Abstract

Flowers are colonized by specific bacterial communities that have been shown to affect floral scent emission and pollinator behavior. Whether these effects translate into changes in the plants’ reproductive success remains unknown. In our study, flowers of Brassica napus were inoculated with the phyllospheric bacteria Pantoea agglomerans and Pseudomonas syringae. Next-generation 16S rRNA gene amplicon sequencing of bacterial communities associated with flowers showed that inoculation was efficient and affected bacterial communities throughout the flowering time of individual flowers. Flowers of B. napus inoculated with P. agglomerans and P. syringae were preferred by pollinators in the field or in olfactometer assays. Presumably due to the increased visitation rates, inoculated plants produced more seeds of tendentially higher quality per flower. Floral scent emissions were affected by time after inoculation and by treatment with bacterial strains, potentially explaining the behavioral responses of pollinators. Controlled laboratory experiments showed that bacteria emit volatiles through their own metabolism and that the concentrations of some floral volatiles can be reduced by bacteria. Furthermore, our results also suggest that bacteria can use floral scent compounds as carbon sources. Our results demonstrate a significant effect of floral bacteria on the pollination and reproduction of entomophilous plants that is at least partly mediated by their effects on floral chemical signaling.

Changes amid constancy: Flower and leaf microbiomes along land use gradients and between bioregions

“…The most abundant taxa found on flowers Pseudomonas sp., Pantoea agglomerans (Enterobacteriaceae) and Pseudomonas syringae are known for their plant growth promoting potential (Preston, 2004;Shariati et al, 2017). Interestingly, it is assumed that P. syringae and P. agglomerans are also involved in modifying floral chemistry and pollinator behaviour, thus affecting the success of host reproduction (Farré-Armengol & Junker, 2019).…”

Context-Dependent Benefits of Aphids for Bacteria in the Phyllosphere

“…Animals can also have an impact on the distribution of microbes in the phyllosphere, such as vectoring of pathogens on crops (Perilla-Henao and Casteel 2016). Although phyllosphere microbes are known to impact animal hosts (Leroy et al 2011a;Kupferschmied et al 2013;Mason et al 2014;Farré-Armengol and Junker 2019), few studies have considered the potential ecological or evolutionary implications of interactions with animals for the microbe (Biere and Bennett 2013). To further complicate matters, tripartite interactions in the phyllosphere often involve plant-mediated traits, which may be difficult to discern from direct interactions (Stout et al 2005;Humphrey et al 2014).…”