Phyllosphere

The below-ground microbial habitats (i.e. the thin-volume of soil surrounding root or subterranean stem surfaces) are referred to as the rhizosphere and laimosphere.

The leaf surface, or phyllosphere, harbours a microbiome comprising diverse communities of bacteria, archaea, fungi, algae and viruses.

[3][12][11] However, although the leaf surface is generally considered a discrete microbial habitat,[13][14] there is no consensus on the dominant driver of community assembly across phyllosphere microbiomes.

For example, host-specific bacterial communities have been reported in the phyllosphere of co-occurring plant species, suggesting a dominant role of host selection.

However, the existing evidence does indicate that phyllosphere microbiomes exhibiting host-specific associations are more likely to interact with the host than those primarily recruited from the surrounding environment.

[24] There can be up to 107 microbes per square centimetre present on the leaf surfaces of plants, and the bacterial population of the phyllosphere on a global scale is estimated to be 1026 cells.

[37][11] Tissue- and species-specific core microbiomes across host populations separated by broad geographical distances have not been widely reported for the phyllosphere using the stringent definition established by Ruinen.

[39][40] These non-peroxide antibacterial properties have been principally linked to the accumulation of the three-carbon sugar dihydroxyacetone (DHA) in the nectar of the manuka flower, which undergoes a chemical conversion to methylglyoxal (MGO) in mature honey.

In contrast, non-core phyllosphere microorganisms exhibited significant variation across individual host trees and populations that was strongly driven by environmental and spatial factors.