Bacterial microbiota associated with flower pollen is influenced by pollination type, and shows a high degree of diversity and species-specificity.
Diverse microorganisms colonise the different plant-microhabitats, such as rhizosphere and phyllosphere, and play key roles for the host. However, bacteria associated with pollen are poorly investigated, despite its ecological, commercial and medical relevance. Due to structure and nutritive composition, pollen provides a unique microhabitat. Here the bacterial abundance, community structure, diversity and colonization pattern of birch, rye, rapes and autumn crocus pollens were examined, by using cultivation, high-throughput sequencing and microscopy. Cultivated bacteria belonged to Proteobacteria, Actinobacteria and Firmicutes, with remarkable differences at species level between pollen species. High-throughput sequencing of 16S rRNA gene amplicon libraries showed Proteobacteria as the dominant phylum in all pollen species, followed by Actinobacteria, Acidobacteria and Firmicutes. Both plant species and pollination type significant influenced structure and diversity of the pollen microbiota. The insect-pollinated species possessed a more similar microbiota in comparison to the wind-pollinated ones, suggesting a levelling effect by insect vectors. Scanning electron microscopy as well as fluorescent in situ hybridisation coupled with confocal laser scanning microscopy (FISH-CLSM) indicated the tectum surface as the preferred niche of bacterial colonisation. This work is the most comprehensive study of pollen microbiology, and strongly increases our knowledge on one of the less investigated plant-microhabitats.
Institute of Applied Microbiology, Research Center for BioSystems, Land Use, and Nutrition (IFZ), Justus-Liebig-University, Giessen, Germany.
Binoy
B
Ambika Manirajan
Institute of Applied Microbiology, Research Center for BioSystems, Land Use, and Nutrition (IFZ), Justus-Liebig-University, Giessen, Germany.
Stefan
S
Ratering
Institut für Integrative Biologie, Stiftung Old Herborn University, Herborn, Germany.
Volker
V
Rusch
MVZ Institut für Mikroökologie GmbH, Herborn, Germany.
Andreas
A
Schwiertz
Institute of Applied Microbiology, Research Center for BioSystems, Land Use, and Nutrition (IFZ), Justus-Liebig-University, Giessen, Germany.
Rita
R
Geissler-Plaum
Institute of Applied Microbiology, Research Center for BioSystems, Land Use, and Nutrition (IFZ), Justus-Liebig-University, Giessen, Germany.
Massimiliano
M
Cardinale
Institute of Applied Microbiology, Research Center for BioSystems, Land Use, and Nutrition (IFZ), Justus-Liebig-University, Giessen, Germany.
Sylvia
S
Schnell
D000818:Animals; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D035264:Flowers / Q000382:microbiology; D015723:Gene Library; D007313:Insecta / Q000502:physiology*; D064307:Microbiota; D011058:Pollen / Q000382:microbiology*; D054817:Pollination; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D058441:Rhizosphere; D013045:Species Specificity
D012336:RNA, Ribosomal, 16S