Background: Plants are critical to global environmental health and food production strategies; most plants utilise flowers as part of their reproduction cycle. Flowers attract pollinators using a range of complex strategies and floral nectar is an essential component of this attraction profile. Nectar is a nutrient rich liquid, containing a range of sugars, organic acids, amino acids, lipids and vitamins, found to be a suitable habitat for a wide range of fungi, but so far, limited bacterial diversity has been detected. Several antimicrobial properties and adverse environmental conditions, such as high osmotic pressure present in the nectar were thought to reduce bacterial numbers.
Results: This study reports the next generation sequencing analysis of the bacterial and fungal diversity in flower nectar. This was achieved in four floral species native to the United Kingdom (Lamium album, white dead nettle; Narcissus pseudonarcissus, daffodil, Hyacinthoides non-scripta, English bluebell and Digitalis purpurea, the common foxglove). All flower species examined had a diverse bacterial and fungal populations present with a core microbiome detected, dominated by Proteobacteria and Firmicutes phyla, while Basidomycota were the most persistent fungal phyla in all of the floral nectar types sampled. However, many unique bacterial and fungal species were detected at lower abundances. Furthermore, in N. pseudonarcissus and D. purpurea floral nectar, the microbial diversity detected in the nectar between flowers exposed to the environment versus non-environment exposed flowers, was different.
Conclusions: These results suggest that floral nectars in different plant species do contain a distinct microbiome and the individual flower microbial community diversity may be affected by floral nectar composition, insect visitation and other environmental factors.